DOLLY TRAILER CONVERTER, SEMI-TRAILER, … · Bearing cleaning and inspection.....20 4 Bearing cup...

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ELECTRICAL AND MECHANICAL VEHICLE H 796-1 ENGINEERING INSTRUCTIONS Issue 1, May 00 DOLLY TRAILER CONVERTER, SEMI-TRAILER, HEAVY, MC4 HAULMARK REPAIR MANUAL This instruction is authorised for use by command of the Chief of Army. It provides direction, mandatory controls and procedures for the operation, maintenance and support of equipment. Personnel are to carry out any action required by this instruction in accordance with GENERAL A 001. UNCONTROLLED WHEN PRINTED

Transcript of DOLLY TRAILER CONVERTER, SEMI-TRAILER, … · Bearing cleaning and inspection.....20 4 Bearing cup...

ELECTRICAL AND MECHANICAL VEHICLE H 796-1ENGINEERING INSTRUCTIONS Issue 1, May 00

DOLLY TRAILER CONVERTER,SEMI-TRAILER, HEAVY, MC4

HAULMARK

REPAIR MANUALThis instruction is authorised for use by command of the Chief of Army. It provides

direction, mandatory controls and procedures for the operation, maintenance and support ofequipment. Personnel are to carry out any action required by this instruction in accordance withGENERAL A 001.

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VEHICLE H 796-1 ELECTRICAL AND MECHANICALIssue 1, May 00 ENGINEERING INSTRUCTIONS

DOLLY TRAILER CONVERTER,SEMI-TRAILER, HEAVY, MC4

HAULMARK

REPAIR MANUALThis instruction is authorised for use by command of the Chief of Army. It provides

direction, mandatory controls and procedures for the operation, maintenance and support ofequipment. Personnel are to carry out any action required by this instruction in accordance withGENERAL A 001.

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ELECTRICAL AND MECHANICAL VEHICLE H 796-1ENGINEERING INSTRUCTIONS Issue 1, May 00

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TABLE OF CONTENTS

Para No. Page No.

TABLE OF CONTENTS ..................................................................................................................... i

LIST OF ILLUSTRATIONS................................................................................................................. vi

LIST OF TABLES............................................................................................................................... viii

ASSOCIATED PUBLICATIONS......................................................................................................... ix

MAINTENANCE SUPPLY ITEM (MSI) IDENTIFICATION................................................................... x

SPECIAL TOOLS............................................................................................................................... xi

LIST OF LUBRICANTS...................................................................................................................... xii

INTRODUCTION ............................................................................................................................... xiii

AXLES - GROUP 9

Axle Assemblies....................................................................................................................... 1

Description ................................................................................................................... 8 1

Removal - equaliser suspension................................................................................. 10 1

Installation - equaliser suspension ............................................................................. 11 1

Removal - single point suspension ............................................................................. 12 2

Installation - single point suspension .......................................................................... 13 2

Axle Alignment ......................................................................................................................... 2

Adjustment ................................................................................................................. 16 3

Wheel Hubs ............................................................................................................................. 3

Removal..................................................................................................................... 17 3

Hub Oil Seal............................................................................................................................. 3

Removal..................................................................................................................... 18 3

Wheel Bearings........................................................................................................................ 3

Bearing cup removal .................................................................................................. 19 3

Bearing cleaning and inspection................................................................................. 20 4

Bearing cup installation .............................................................................................. 25 4

Hub Oil Seal............................................................................................................................. 5

Installation.................................................................................................................. 27 5

Wheel Hub Installation ............................................................................................................. 5

Inspection................................................................................................................... 28 5

Installation.................................................................................................................. 29 5

Hubodometer ........................................................................................................................... 6

Replacement .............................................................................................................. 30 6

Welding.................................................................................................................................... 6

Areas ......................................................................................................................... 31 6

Specifications........................................................................................................................... 7

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Para No. Page No.

WHEELS - GROUP 11

Description............................................................................................................................... 8

Maintenance ............................................................................................................................ 8

Removal..................................................................................................................... 33 8

Disassembly............................................................................................................... 34 8

Cleaning and inspection ............................................................................................ 36 8

Reassembly ............................................................................................................... 37 8

Installation.................................................................................................................. 38 8

Specifications .......................................................................................................................... 9

BRAKES - GROUP 12

Description............................................................................................................................... 10

General.................................................................................................................................... 10

Brake Air Systems ................................................................................................................... 10

Air Reservoirs .......................................................................................................................... 11

Spring Brake Chambers........................................................................................................... 11

Foundation Brakes................................................................................................................... 11

Service Relay Valve................................................................................................................. 11

Operation................................................................................................................................. 12

Applying..................................................................................................................... 55 12

Balancing ................................................................................................................... 56 12

Releasing................................................................................................................... 57 12

Pilot Relay Valve...................................................................................................................... 12

Operation ................................................................................................................... 58 12

Balancing ................................................................................................................... 59 13

Releasing................................................................................................................... 60 13

Spring Brake Control Valve ...................................................................................................... 13

Operation ................................................................................................................... 61 13

Charging .................................................................................................................... 62 13

Park application ......................................................................................................... 63 14

Brake System Failure............................................................................................................... 14

Emergency application with service system failure ..................................................... 65 14

Yard Release Valve ................................................................................................................. 14

Spring Brake Chambers........................................................................................................... 15

Spring brake released position ................................................................................... 70 15

Service brake application ........................................................................................... 71 15

Spring brake application............................................................................................. 72 15

Mechanical release .................................................................................................... 73 15

Slack Adjusters ........................................................................................................................ 16

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Para No. Page No.

Functional Tests....................................................................................................................... 16

Air Control Systems - Precautions............................................................................................ 17

Brake Relay Valves.................................................................................................................. 17

Removal..................................................................................................................... 77 17

Disassembly............................................................................................................... 78 17

Cleaning and inspection ............................................................................................. 79 18

Reassembly ............................................................................................................... 81 18

Installation.................................................................................................................. 82 19

Spring Brake Control Valve ...................................................................................................... 19

Removal..................................................................................................................... 83 19

Disassembly............................................................................................................... 84 19

Cleaning and inspection ............................................................................................. 85 21

Reassembly ............................................................................................................... 86 21

Installation.................................................................................................................. 87 21

Pilot Relay Valve...................................................................................................................... 21

Removal..................................................................................................................... 88 21

Disassembly............................................................................................................... 89 22

Cleaning and inspection ............................................................................................. 90 23

Reassembly ............................................................................................................... 91 23

Installation.................................................................................................................. 93 23

Yard Release Valve.................................................................................................................. 24

Removal..................................................................................................................... 94 24

Disassembly............................................................................................................... 95 24

Reassembly ............................................................................................................... 96 24

Installation.................................................................................................................. 97 24

Spring Brake Chamber............................................................................................................. 25

Removal..................................................................................................................... 98 25

Disassembly............................................................................................................... 99 25

Cleaning and inspection ........................................................................................... 100 27

Reassembly ............................................................................................................. 101 27

Installation................................................................................................................ 102 28

Wheel Brake Assembly ............................................................................................................ 28

Disassembly............................................................................................................. 103 28

Reassembly ............................................................................................................. 104 30

Brake Adjustment..................................................................................................................... 30

Adjustment ............................................................................................................... 106 30

Fault Finding ............................................................................................................................ 31

Specifications........................................................................................................................... 32

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Para No. Page No.

SUSPENSION - GROUP 13

General.................................................................................................................................... 33

Equaliser Suspension .............................................................................................................. 33

Description............................................................................................................... 110 33

Springs .................................................................................................................... 111 33

Spring hangers......................................................................................................... 112 33

Equaliser assembly .................................................................................................. 113 33

Radius rods.............................................................................................................. 114 33

Equaliser Assembly.................................................................................................................. 34

Bush replacement .................................................................................................... 115 34

Removal of equaliser beam...................................................................................... 116 34

Installation of equaliser beam................................................................................... 117 34

Radius Rods ............................................................................................................................ 34

Removal................................................................................................................... 118 34

Installation................................................................................................................ 119 34

Springs .................................................................................................................................... 35

Removal................................................................................................................... 120 35

Installation................................................................................................................ 121 35

Spring Hangers........................................................................................................................ 35

Removal................................................................................................................... 122 35

Replacement............................................................................................................ 123 35

Welding ................................................................................................................................... 35

Single Point Suspension .......................................................................................................... 35

Description............................................................................................................... 125 35

Springs .................................................................................................................... 126 35

Spring hangers......................................................................................................... 127 35

Spring Hangers........................................................................................................................ 36

Bush replacement .................................................................................................... 128 36

Spring Seats ............................................................................................................................ 36

Rubber pad replacement.......................................................................................... 129 36

Springs .................................................................................................................................... 36

Removal................................................................................................................... 130 36

Installation................................................................................................................ 131 38

Spring Mounting Brackets ........................................................................................................ 38

Removal................................................................................................................... 132 38

Replacement........................................................................................................... .133 38

Welding ................................................................................................................................... 38

Specifications .......................................................................................................................... 39

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ELECTRICAL AND MECHANICAL VEHICLE H 796-1ENGINEERING INSTRUCTIONS Issue 1, May 00

Amended Sep 04

AL 1 v

Para No. Page No.ELECTRICAL - GROUP 15

Description ................................................................................................................................. ............. 40

Specifications ............................................................................................................................. ............. 41

FRAME ASSEMBLY - GROUP 16

Description ................................................................................................................................. ............. 42

Dolly Frame............................................................................................................. 138............. 42

Drawbar................................................................................................................... 139............. 42

Drawbar Assembly ..................................................................................................................... ............. 42

Removal .................................................................................................................. 140............. 42

Installation ............................................................................................................... 141............. 42

Fifth Wheel ................................................................................................................................. ............. 43

Removal .................................................................................................................. 142............. 43

Disassembly............................................................................................................ 143............. 43

Reassembly ............................................................................................................ 144............. 43

Installation ............................................................................................................... 145............. 45

Drawbar Eye............................................................................................................................... ............. 48

Inspection Standard ................................................................................................ 146............. 48

Removal and Replacement..................................................................................... 147............. 48

Welding ................................................................................................................................ 148............. 49

Frame Members...................................................................................................... 149............. 49

Spring Hangers/Mounting Brackets ........................................................................ 150............. 49

Decking ................................................................................................................... 151............. 49

Specifications ............................................................................................................................. ............. 49

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LIST OF ILLUSTRATIONS

Figure Number Title Page Number

1 Hub seal installing tool. xi

2 Hub lock nut wrench. xi

3 Hub nut tube wrench. xi

4 Spring brake release tool. xi

5 Fifth wheel lock tester. xi

6 Dolly Trailer Converter, Semi-Trailer, Heavy, MC4 Haulmark xiii

7 Equaliser suspension layout. 1

8 Single point suspension layout. 2

9 Axle alignment diagram. 3

10 Wheel hub assembly - exploded view. 4

11 Wheel nut and brake drum torque sequence. 5

12 Axle beam “no-weld” areas. 6

13 Dolly Converter braking system. 10

14 Brake relay valve - sectioned view. 11

15 Brake relay valve - applying. 12

16 Brake relay valve - balanced position. 12

17 Brake relay valve - releasing. 12

18 R8-P pilot relay valve. 12

19 R8-P pilot relay valve - applying. 13

20 R8-P pilot relay valve - balanced position. 13

21 Spring brake control valve - sectioned view. 13

22 Spring brake control valve - charging. 14

23 Spring brake control valve - park application. 14

24 Spring brake control valve - brake system failure. 14

25 Yard release valve - sectioned view. 15

26 Spring brake chamber - sectioned view. 15

27 Brake relay valve mounting. 17

28 Brake relay valve - exploded view. 18

29 Spring brake control valve mounting. 19

30 Spring brake control valve - exploded view. 20

31 Brake pilot relay valve - exploded view. 22

32 Yard release valve - exploded view. 24

33 Spring brake chamber - exploded view. 26

34 Wheel brake assembly - exploded view. 29

35 Brake camshaft and mountings - exploded view. 29

36 Brake adjustment. 30

37 Equaliser suspension layout. 33

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Figure Number Title Page Number

38 Suspension equaliser. 34

39 Radius rod mounting bushes and pins. 35

40 Single point suspension assembly. 36

41 Single point suspension - exploded view. 37

42 Electrical circuit diagram. 40

43 Drawbar pivot bushes. 42

44 Fifth wheel layout. 43

45 Fifth wheel assembly - exploded view. 44

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LIST OF TABLES

Table Number Title Page Number

1 Maintenance Supply Item (MSI) Identification x

2 Special Tools xi

3 List of Lubricants xii

4 Fault Finding (Brakes) 31

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ASSOCIATED PUBLICATIONS

1. Standing Orders for Vehicle Operators, Volume 2, B Vehicles.

2. TGM 120 Record Book for Service Equipment - Army.

3. User Handbook.

4. EMEI VEH H 790 Data Summary.

5. EMEI VEH H 799 Servicing Instruction.

6. Repair Parts Scale - RPS 02240 - Tandem & 02241 - Single Point

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MAINTENANCE SUPPLY ITEM (MSI) IDENTIFICATION

Table 1

Maintenance Supply Item (MSI) Identification

Axle assemblies - Centre of axle beam, opposite brake chamber mountings

Fifth wheel - Leading edge of Fifth Wheel

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SPECIAL TOOLS

Table 2

Special Tools

Part No/Item Name Para No.

Hub seal installing tool 27

Hub lock nut wrench 17, 29

Hub nut tube wrench 17, 29

Spring brake release tool 10-13, 17, 29, 69, 73, 98, 99, 101, 102

Fifth wheel lock tester 144

Figure 1Hub seal installing toolManuf. No. 550-5039

Figure 2Hub lock nut wrenchManuf. No. CS 39/2

Figure 3Hub nut tube wrenchManuf. No. CS 213

Figure 4Spring brake release tool

Manuf. No. M9007003

Figure 5Fifth wheel lock tester

Manuf. No. TF-TLN-1500

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LIST OF LUBRICANTS

Table 3

List of Lubricants

Equipments Lubricant

All grease points XG 274

Brake control valves XG 315

Wheel bearings OEP 600 or XG 274

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DOLLY TRAILER CONVERTER,SEMI-TRAILER, HEAVY, MC4

HAULMARK

REPAIR MANUAL

Introduction

1. This EMEI contains procedures for removing,dismantling, repairing, assembling and installing thecomponents of the Dolly Trailer Converter, Semi-Trailer, Heavy, MC4 Haulmark. Where applicableinstructions for the adjustment, lubrication and minorservicing of these items are included.

2. Prevent dirt and foreign objects from enteringany components by placing clean temporarycoverings over all exposed openings, includinghoses, tubes and lines.

3. When disconnecting electrical connectors,hoses and fittings, remove clamps as required togain slack and avoid damage to connectors andfittings.

WARNINGBefore disconnecting any electricalsystem components, disconnect thedolly converter electrical connectorfrom the towing vehicle.

4. Discard all used gaskets, seals, cotter pins,tab washers, lock pins, key washers and lockwashers.

5. Use only those lubricants specified in theServicing Instruction EMEI VEH H 799, UserHandbook and this Repair Manual when replenishinglubricants.

6. Any fastening or fitting being tightened toprescribed torques are to have dry, clean threadsunless otherwise specified. Thread sealants are tobe applied to dry, clean oil free threads.

7. For warranty repair provisions refer to theUser Handbook.

Figure 6Dolly Trailer Converter, Semi-Trailer, Heavy, MC4

Haulmark

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ELECTRICAL AND MECHANICAL VEHICLE H 796-1ENGINEERING INSTRUCTIONS Issue 1, May 00

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AXLES - GROUP 9

Axle Assemblies

8. Description. The axles fitted to this trailer area single, tubular beam type, manufactured by DanaSpicer. They are fitted with 16.5 inch x 7 inch,internal expanding shoe type brakes. The axles arefitted with 20 inch, spider type wheel hubs. Theseare carried by two tapered roller, oil or greaselubricated bearings.

9. The axles are connected to two different designsof suspension, namely the equaliser type suspensionand the single point suspension. The methods used toremove the axles from both designs are detailed inpara 10 and 12 and the installation procedures aredetailed in para 11 and 13.

10. Removal - equaliser suspension. Prior toremoval of any components of the dolly converterrunning gear, correctly support the dolly converterframe, with all weight removed from the suspensioncomponents. Remove the axle assemblies using thefollowing procedure:

a. Ensure that the weight of each axle iscorrectly and safely supported.

b. Remove the wheels from the effectedaxle.

c. Disconnect the two air lines at eachspring brake chamber, ensuring that eachline is labelled to ensure correctconnection on assembly.

d. If the wheel hubs are to be removed,release the spring brakes using the springbrake release tools provided. They will befound fitted to the boss on the side of thespring brake chamber adapter housings.

e. Remove the radius rod bolts, taperedbushes and steel sleeve securing the tworadius rods to the axle and swing theradius rods clear. If insufficient clearanceis available, remove the radius rodscompletely.

f. Remove the ‘U' bolt nuts securing theaxle to the springs, and extract the ‘U’bolts.

g. Using a suitable jack lower the axle,taking care that the axle does not roll toone side due to weight imbalance.

h. Return the ‘U’ bolts to their respectivesprings, to prevent loss.

11. Installation - equaliser suspension. Theaxle assemblies connected to the equaliser typesuspension are to be installed in the followingsequence:

a. Using a suitable jacking device, lift theaxle assembly up to the springs, ensuringthat the spring centre bolts are correctlylocated into the spring seats welded tothe axle tube.

b. Place the ‘U’ bolts in position, ensuringthat all threads are in serviceable order.Fit the flat washers and nuts. Torque the‘U’ bolt nuts evenly to the specifiedtorque.

c. Fit the radius rods and torque the radiusrod bolts to the specified torque.

Figure 7Equaliser suspension layout.

Front spring hanger Equaliser assembly Rear spring hanger

Fixed radius rod

Axle assembliesAdjustable radius rod

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d. Connect the air lines to the spring brakechambers, ensuring that the hoses areconnected to the correct ports.

e. If fitted, remove the spring brake releasetools from the spring brake chambers.Replace them in the bosses located onthe side of the spring brake chamberadapter housings.

f. Check the brake adjustment, adjust ifnecessary as specified in Group 12, para105.

g. Check axle alignment and adjust asrequired. Refer to para 14.

h. Refit the wheels to the hubs.

12. Removal - single point suspension. Prior toremoval of any components of the dolly converterrunning gear, correctly support the dolly converterframe, with all weight removed from the suspensioncomponents. Remove the axle assemblies using thefollowing procedure:

Figure 8Single point suspension layout.

a. Ensure that the weight of each axle iscorrectly and safely supported.

b. Remove the wheels from the effectedaxle.

c. Disconnect the two air lines at eachspring brake chamber, ensuring that eachline is labelled to ensure correctconnection on assembly.

d. If the wheel hubs are to be removed,release the spring brakes using the springbrake release tools provided. They will be

found fitted to the boss on the side of thespring brake chamber adapter housings.

e. Remove the ‘U’ bolt locknuts, nuts andwashers securing the axle to the springs.Slide the lower clamps off the ‘U’ bolts.

f. Using a suitable jack lower the axle,taking care that the axle does not roll toone side due to weight imbalance.

13. Installation - single point suspension. Theaxle assemblies connected to the single point typesuspension are to be installed in the followingsequence:

a. Using a suitable jacking device, lift theaxle assembly up to the springs ensuringthat the dowels in the upper clamps,welded to the axle tube, are correctlylocated into the bottom springs.

b. Fit the lower clamps over the ‘U’ bolts,ensuring that all threads are inserviceable order. Fit the flat washers andnuts. Torque the ‘U’ bolt nuts evenly tothe specified torque.

c. Fit the locknuts onto the ‘U’ bolts andtorque the nuts to the specified torque.

d. Connect the air lines to the spring brakechambers, ensuring that the hoses areconnected to the correct ports.

e. If fitted, remove the spring brake releasetools from the spring brake chambers.Replace them in the bosses located onthe side of the spring brake chamberadapter housings.

f. Check the brake adjustment, adjust ifnecessary as specified in Group 12, para105.

g. Refit the wheels to the hubs.

Axle Alignment

14. The dolly converter axles fitted with the equalisertype suspensions are to be aligned so that the centrelines of the two axles are at right angles to the centreline of the dolly converter frame. The allowabletolerance for either dimension x or y is +/- 1 mm. Noalignment checks are necessary on the single pointunits. Refer to Figure 9.

15. Prior to carrying out any axle alignmentadjustment, the following checks are to be carried out:

‘U’ bolt Upperclamp

Axle

Lowerclamp

Suspensionbracket

assembly

‘U’ boltbracket

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a. Ensure that all suspension componentsare in good condition.

b. Ensure that all tyre pressures are correct.

c. Ensure that the dolly is on flat, levelground.

d. Ensure that the suspension is not underany tension due to the dolly being turnedwithin 20 metres of the test area.

16. Adjustment. To alter the axle alignment:

a. Loosen the four clamp bolts on the RHradius rods.

b. Turn the centre section of the applicableradius rod to alter the axle alignment asrequired.

NOTEThe front axle of the applicable bogiegroup is to be correctly aligned beforeattempting to align the rear axle.

Adjustment of the adjustable radius rodaffects the measurement obtained atboth ends of the axle assembly.

Figure 9Axle alignment diagram.

Wheel Hubs

17. Removal

a. Place a suitable jack beneath theapplicable axle and jack the wheels to beremoved clear of the ground.

b. Place a safety stand/s or an equivalentblocking facility beneath the axle/s.

c. Lower the axle to the stand ensuring thatthe wheel/s remain clear of the ground.

d. Remove the nuts securing the wheels tothe hub and remove the wheels.

e. Using the spring brake release toolsprovided, mechanically release the springbrakes.

f. If working on the unit with oil filledbearings, remove the oil filling pluglocated on the side of the hub cap (12).Place a suitable container under the hub,rotate the wheel to allow the lubricating oilto drain. Refer to Figure 10.

g. Remove the six hexagon headed screwssecuring the hub cap (12) to the hub (5).Remove the hub cap.

h. Using the hub lock nut wrench, removethe wheel bearing lock nut (10).

i. Remove the hub nut lock plate (9).

j. Using the hub nut tube wrench, removethe bearing adjustment nut (8).

k. Support the wheel hub and brake drumassembly with a suitable trolley jack.

l. Remove the outer bearing cone (7) fromthe hub and stub axle.

m. Remove the hub assembly by sliding it offthe stub axle.

Hub Oil Seal

18. Removal. Following removal of the wheel hubassembly as detailed above, remove the inner hub sealas follows.

a. Position the wheel hub and brake drumassembly on a solid surface with thewheel studs facing upwards.

b. Using a long brass drift placed throughthe centre of the hub, against the innerrace of the inner wheel bearing (3 & 4),drive the hub seal (2) and bearing fromthe hub. Ensure that the bearing cage isnot damaged.

Wheel Bearings

19. Bearing cup removal. With the wheel hub andhub seals removed as described earlier, remove thewheel bearing cups by driving them out with a long

Y

Y

X

X

90°

90°

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brass drift placed through the hub centre, against theinner face of the respective cup. The drift should beplaced in alternate positions around the cup to ensurethat it is driven evenly from the hub.

NOTEWhen fitting used bearing cups, ensurethat they are matched, and remainwith, their respective bearing cones.

20. Bearing cleaning and inspection. Wash thebearing cups and cones in suitable clean, solvent usinga stiff brush, but not steel. Avoid spinning the coneswhen cleaning.

21. Wipe the cleaned parts dry with clean absorbentcloth or paper. Clean and dry hands and all tools usedin the service operation. Lubricant will not adhere to asurface that is wet with solvent. Solvent will also dilutethe lubricant. CLEANLINESS IS MOST IMPORTANT.

22. Inspect the bearing cup for:

a. Discolouration, straw or blue colouring.

b. Chips or scoring on the bearing surface.

c. Flaking of the case hardening.

23. Inspect the bearing cone for:

a. Discolouration of the tapered rollers.

b. Chipping or scoring of the casehardening.

c. Flaking of the case hardening.

d. Acceptable wear limits on wear backsurface, i.e. large end of the taperedroller.

e. Condition of the tapered roller cage.

24. Discard the bearing cup and cone if any defectsare found. These must be replaced as a matched set.

25. Bearing cup installation. Before fitting bearingcups, carry out the following actions:

Item Description Item Description Item Description

1. Hub seal sleeve 5. Wheel hub 9. Wheel hub nut lock plate

2. Hub seal 6. Outer wheel bearing cup 10. Wheel hub lock nut

3. Inner wheel bearing cone 7. Outer wheel bearing cone 11. Wheel hub cap gasket

4. Inner wheel bearing cup 8. Wheel bearing adjusting nut 12. Wheel hub cap

Figure 10Wheel hub assembly - exploded view.

4

12

3

5

1211

1098

76

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a. Check that the wheel hub is free from anydamage or wear that would render itunserviceable or affect the correct fittingof the bearing cups.

b. When fitting used cups, ensure that thebearing surface is serviceable and freefrom discolouring, chips, flaking, scoringor other damage that will render itunserviceable.

c. Apply a faint smear of grease around theinner surface of the hub through whichthe bearing cup is to pass.

d. Place the inner bearing cup (4) in positionand drive it into position using a suitablehammer and brass drift. Ensure that thedrift is placed in alternate positionsaround the cup to ensure that the cup isdriven evenly into the hub.

CAUTIONDrifts used for fitting bearing cupsmust be free of all burrs and jaggededges to prevent dislodging ofbrass chips into the wheel hub andbearings.

26. When a solid metallic knock is heard, the cupwill be fully in position in the hub.

Hub Oil Seal

27. Installation. Before installation of the hub seal,check that the hub axle land is clean and free from dirtor other foreign material. Fit the new hub seal asfollows:

a. Coat the axle land with a thin coat ofLoctite 515 Forma gasket compound,Hylamar or other brand name non-hardening gasket material.

b. Using the hub seal installing tool, drivethe inner hub seal (2) into position in thestub axle. Refer to Figure 1, page xi.

NOTEThe two parts of the hub seal are fittedto the stub axle during assembly. Thehub seal is pushed into the wheel hubduring installation.

Wheel Hub Installation

28. Inspection. Prior to installation of the wheelhub and brake drum assembly ensure that:

a. The brake drum mounting bolts areserviceable and correctly torqued. Referto Specifications and Figure 11.

b. The inner bearing cup is serviceable andcorrectly fitted.

c. The inner wheel bearing cone is correctlylubricated and fitted.

d. The hub seal is serviceable and correctlyfitted to the stub axle.

e. The bearings fitted to the greaselubricated axles must be correctly packedwith grease before replacing the hub cap.

29. Installation. Install the wheel hub as follows.

a. Using suitable trolley jack or other deviceto carry the wheel hub, slide the hub andbrake drum assembly onto the stub axleensuring that it is pushed on as far aspossible. Refer to Figure 10.

b. Fit the outer wheel bearing cone (7),ensuring that it is correctly lubricated.

c. Fit the bearing adjusting nut (8) to thestub axle. Using the hub nut tube wrench,adjust the bearing preload by screwingthe nut on until tight and backing it off 1/4of a turn. Spin the hub while tighteningthe bearing nut.

Figure 11Wheel nut and brake drum torque sequence.

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NOTEEnsure that the air tank is fully chargedand that the brakes are released toprevent brake shoe drag duringadjustment.

d. Fit the hub nut lock plate (9) to the stubaxle and locate the bearing adjusting nutlock pin into one of the holes around thehub nut lock plate (9). It may benecessary to turn the nut slightly to obtainproper alignment or to reverse the lockplate.

e. Fit and tighten the hub lock nut (10) ontothe stub axle using the hub lock nutwrench. Use a 1.5 to 2 lb hammer totighten the nut. Refer to Figure 2, page xi.

f. Fit the hub cap gasket (11) to the wheelhub (12) and install the hub cap using thesix hexagon headed screws and lockwashers.

g. If working on the unit with oil filledbearings, rotate the hub until the oil fillingplug is in the 12 o’clock position. Fill thehub with the recommended oil until thesight glass is full.

h. Fit the oil plug, rotate the hub for severalrevolutions and allow the oil level to settle.

i. Add oil gradually until the oil is up to theoil level mark on the sight glass

j. Remove the spring brake release tool,replace it in the stowage boss andsecure.

k. Fit the wheel to the hub and secure it withthe five wheel clamps and nuts. Tightenthe wheel nuts evenly to the specifiedtorque and tightening sequence. Refer toSpecifications and Figure 11.

l. Remove the stands and lower the wheelsto the ground.

CAUTIONWheel nuts must be retensionedafter travelling approximately 50km, following the refitting ofwheels.

Hubodometer

30. Replacement. A hubodometer is fitted to theRH rear side of the dolly converter. The fitting of thehubodometer requires a raised, hubodometer windowto be fitted to the standard hub cap. The hubodometeris a non-repairable item and should be discarded whendefective.

a. Remove the six hexagonal head screwssecuring the hubcap to the RHR wheelhub and remove the hub cap andhubodometer assembly.

b. Remove the hexagonal nut located insidethe hub cap. Remove the internal starwasher and withdraw the hubodometerfrom the hub cap.

c. Fit a new hubodometer to the hub capand secure with the internal star washerand hexagonal nut.

d. Refit the hub cap and hubodometer to thewheel hub using the six hexagon headedscrews. Ensure that the gasket is properlyseated when fitting the hub cap to thewheel hub.

Welding

31. Areas. All welds on these axles are to be locatedin the area of minimum stress and as near to thehorizontal direction as possible. It is important that allwelds are excluded from the area within 25 mm ofeither side of the vertical centre line as shown in Figure12.

Figure 12Axle beam “no-weld” areas.

37 mm.

Noweld

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SPECIFICATIONS

‘U’ Bolt torque ......................................................................................................................... 415 Nm (310 lb ft)

Radius rod mounting bolt torque ............................................................................................... 100 Nm (75 lb ft)

Radius rod clamp bolt torque..................................................................................................... 100 Nm (75 lb ft)

Brake drum mounting bolt torque ............................................................................................ 260 Nm (190 lb ft)

Axle alignment tolerance....................................................................................................................... +/- 1 mm

Maximum wheel runout .............................................................................................................................. 2 mm

Tyre Pressure (cold) laden .......................................................................................................690 kPa (100 psi)

Tyre pressure (cold) unladen.......................................................................................................550 kPa (80psi)

Wheel nut torque .................................................................................................................... 245 Nm (180 lb ft)

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WHEELS - GROUP 11

Description

32. The wheels fitted to this dolly converter are8.25 x 22.5, single piece, pressed steel, tubelesstype, fitted with 11R 22.5 x 16 ply rating tyres.

Maintenance

33. Removal.

a. Jack up the respective axle and supportit using a safety stand or otheracceptable means of support.

b. Loosen the five clamp nuts evenlybefore removal.

c. Remove the five nuts and clamps.

d. Noting the respective positions of thewheel rims on the hubs, remove theother wheel spacer and inner wheelfrom the wheel hub.

34. Disassembly. The tyres should preferablybe removed from the rim using a suitable tyredemounter, however, if not available the tyres maybe removed using conventional tyre levers. Caremust be taken to prevent damage to the tyre beadduring removal.

35. To assist removal and help prevent tyrebead damage it is suggested that soapy water bespread around the bead. This will assist byreducing the friction between the tyre and thewheel rim.

36. Cleaning and inspection.

a. Prior to cleaning of the wheel riminspect it for any obvious cracking,fractures or other damage which mayrender it unserviceable.

b. Using whatever suitable meansavailable clean the wheel rim of any rustor scale build up on the internal surface.

c. After cleaning inspect the rim fordamage, cracks etc.

d. Inspect the valve stem seals forserviceability. Replace if defective.

e. Remove all stones etc. from the tyretread pattern. Inspect tread depth forserviceability. Inspect tread and externalwall surfaces for damage which willrender the tyre unserviceable.

f. Using a tyre spreader, if available,inspect the inner tyre surface for anycuts, abrasions etc. Inspect the tyrebeads for serviceability.

37. Reassembly. If the tyre has been removedas a result of a puncture then it must bereassembled using a suitable radial tube tyre. It issuggested that soapy water be used around thetyre bead to aid installation.

a. Fit one side of the tyre over the wheelrim, preferably using a tyre demounter,however a rubber mallet and tyre leversmay be used with caution.

b. If required, fit a tube to the tyre,ensuring that the valve is correctlylocated in the wheel rim and that thetube is correctly positioned.

c. Fit the remaining side of the tyre overthe wheel rim taking care not to pinchthe tube between the tyre bead and therim.

d. Inflate the tyre to the specified pressure.

CAUTIONIf refitting a used tyre it must befitted so that it will rotate in thesame direction as it was prior toremoval. This is to preventpremature tyre failure caused byreversal of direction of rotation.

38. Installation.

a. Fit the inner wheel spacer and outerwheel to the hub in that order. Ensurethat the wheel rims are correctly alignedand fit the five wheel clamps and nuts.

b. Tighten the clamp nuts evenly to thecorrect torque to ensure proper, evenclamping of the wheel to the hub. Referto Specifications for maximum wheelrun out and wheel nut torque figures.

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SPECIFICATIONS

Maximum wheel runout .............................................................................................................................. 2 mm

Tyre pressure (cold) .................................................................................................................690 kPa (100 psi)

Wheel nut torque .................................................................................................................... 245 Nm (180 lb ft)

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BRAKES - GROUP 12

Description

General

39. The air actuating system is a compressed airsystem and the foundation brakes are manufacturedby Dana/Spicer. The brake system layout is shown inFigure 13.

Brake Air Systems

40. The brake air system is a twin line type withspring brake chambers provided for each wheel and isdesigned to comply with ADR 38.

41. An R-12 service brake relay valve is mounteddirectly onto the rear air reservoir of the dolly converter.This valve functions as a relay station to speed up theapplication and release of the service brakes. The relayvalve delivers air from the reservoir to, or release air toatmosphere from, the service brake chambers. Theseactions are carried out in proportion to the air pressureapplied at the control port. The service relay valve

functions in response to the control air delivered fromthe pilot relay valve.

42. The pilot relay valve fitted to the rear airreservoir is a Bendix R8-P relay valve. This valve iscontrolled directly from the prime mover brake controlvalve. The function of this relay valve is to delivercompressed air to the service relay valve. Thedelivered air pressure is in proportion to the airpressure sensed at it’s own control port.

43. The spring brakes are controlled by a SR-3spring brake control valve which is mounted directlyonto the rear air reservoir of the dolly converter. Thepurpose of the spring brake control valve is to controlthe operation of the spring brakes during parking andemergency conditions.

44. During normal operation the spring brake controlvalve will prevent the passage of compressed air to thespring brakes until the required air pressure,approximately 380 kPa, is obtained in the supply line.This ensures that the prime mover has the minimumrequired air pressure before replenishing the reservoirs

Figure 13Dolly converter braking system.

Reservoir

SR-3Springbrakecontrolvalve

R8-P Pilotrelay valve

Reservoir

R12relayvalve

Front ofDolly Converter

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or releasing the spring brakes. Once this minimum airpressure has been achieved, compressed air is thendirected to both the air reservoirs and the spring brakechambers concurrently.

45. During parking, when the parking control valve isactuated, air pressure is exhausted from the trailersupply line. When this occurs the spring brake controlvalve exhausts all air from the spring brake chambersthus causing them to be applied by the internal springpressure.

46. In the event that air pressure should be lost fromthe air reservoir whilst the spring brakes are released,the spring brake control valve will retain a pressure ofapproximately 354-415 kPa in the supply line. Thespring brakes will remain released, allowing the dollyconverter to be moved to a safe location for parking.Once the air pressure in the supply line has beenexhausted the spring brakes will not release until thesystem fault has been rectified.

47. A yard release valve is fitted to the dollyconverter. This valve is fitted to allow the brakes to bereleased using air from the reservoirs for ease ofmovement within a safe area only.

48. The yard release valve is pressure sensitive andwill automatically move from the applied to the exhaustposition as supply pressure is reduced to a setminimum. (140-415 kPa).

49. Glad hand type couplings are provided for easyconnection between the trailer, dolly converter andprime mover, with stop cocks and dummy couplingsprovided on the dolly at the trailer connection points.

Air Reservoirs

50. The dolly converter is fitted with two airreservoirs which provide the air required for theapplication of the brakes. The larger of the twoprovides the bulk of the air required for brakeapplication. The smaller air reservoir providesadditional compressed air available for brakeapplication.

51. Each air reservoir is fitted with a condensationdrain valve which is actuated by means of individualpull cords, located adjacent to the respective airreservoirs.

Spring Brake Chambers

52. Each wheel brake is actuated by a type 3030spring brake which provides service, parking andemergency braking under the direct control of thebrake relay and spring brake control valves. Eachspring brake chamber has two separate air chambers,

each equivalent in size, to provide the required brakingfunctions. A heavy duty spring fitted into the springbrake chamber applies the brakes when air pressure isexhausted from the spring brake chamber. The springbrakes may be released mechanically by means of arelease bolt to aid in recovery of the dolly converter.

Foundation Brakes

53. The foundation brakes are a 16.5 in. diameter, 7in. wide, internal expanding, twin-shoe type. The twobrake shoes are each mounted on individual non-adjustable anchor pins which allow the brake shoes topivot under the influence of an ’S’ cam. The ’S’ cam isfitted with an adjustable slack adjuster which performsa twofold purpose in that it provides a means toconnect the camshaft to the brake chamber pushrod,thus converting the reciprocating motion of the brakechamber into the required rotary motion of thecamshaft; it also provides a quick and simple means ofbrake adjustment through the use of an internal wormand wheel gear. Adjustment is locked by a springloaded locking collar.

Service Relay Valve

54. The brake relay valve is a Bendix model R-12 airoperated, graduating directional control valve with ahigh capacity and fast response. This valve is fitted toincrease the speed of application and release of thebrakes. This valve is direct mounted onto the airreservoir and operates as a remote controlled brakevalve controlled by the operation of the service pilotvalve. This valve delivers or releases air, to or from,the brake chambers, in response to the control airdelivered to it from the service pilot relay service valve.

Figure 14Brake relay valve - sectioned view.

Control port Relaypiston

Inlet/exhaust

valveseat

To servicebrake

Supplyport

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Operation

55. Applying. Air pressure delivered to the serviceport enters the small cavity above the piston andmoves the piston down. The exhaust seat moves downwith the piston and seats on the inner or exhaustportion of the inlet/exhaust valve, sealing off theexhaust passage. At the same time, the outer or inletportion of the inlet/exhaust valve moves off its seat,permitting supply air to flow from the reservoir, past theopen inlet valve and into the chambers.

Figure 15Brake relay valve - applying.

56. Balancing. The air pressure being delivered bythe open inlet valve also is effective on the bottom areaof the relay piston. When air pressure beneath thepiston balances with the service air pressure above,the piston lifts slightly and the inlet spring returns theinlet valve to its seat. The exhaust remains closed asthe service line pressure balances the deliverypressure. As air pressure is changed, the valve reactsinstantly to the change holding the brake application atthe desired level.

Figure 16Brake relay valve - balanced position.

57. Releasing. When air pressure is released fromthe service port and air pressure in the cavity abovethe relay piston is exhausted, air pressure beneath thepiston lifts the relay piston and the exhaust seat movesaway from the exhaust valve, opening the exhaustpassage. With the exhaust passage open, the airpressure in the brake chambers is then permitted toexhaust through the exhaust port, releasing the brakes.

Figure 17Brake relay valve - releasing.

Pilot Relay Valve

58. Operation. Air pressure entering the serviceport flows into the cavity between the cover and the topof the relay piston. This air pressure acting on thesurface of the piston forces it down. The exhaust valveseat moves down with the piston and seats on theinner or exhaust portion of the inlet and exhaust valve,sealing off the exhaust passage. At the same time theouter or inlet port of the inlet and exhaust valve movesoff its seat, permitting supply air to flow from thereservoir past the open inlet valve and out the deliveryport.

Figure 18R8-P pilot relay valve.

Inlet/exhaust

port

Piston

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Figure 19R8-P pilot relay valve - applying.

Figure 20R8-P pilot relay valve - balanced position.

59. Balancing. The air pressure being delivered bythe open inlet valve also is effective on the bottom areaof the relay piston. When this delivery air pressurebeneath the piston equals the service air pressureabove, the piston moves slightly and the inlet springreturns the inlet valve to its seat. The exhaust remainsclosed as service line pressure balances deliverypressure.

60. Releasing. When air pressure is exhaustedfrom the service port, the diaphragm in the quickrelease moves, blocking the service inlet and openingthe exhaust of the quick release allowing the air thatwas acting on the relay piston to be exhausted at thequick release. When the air above the relay piston isexhausted, the air beneath the piston will lift the pistonand the exhaust seat moves off the exhaust valve,exposing the exhaust passage to the atmosphere.With the exhaust passage open, the air pressureapplied to the relay valve will be exhausted out of theexhaust port to the atmosphere.

Spring Brake Control Valve

61. Operation. The spring brake control valve isfitted into the braking system to control the springbrakes during parking and emergency applications. Itautomatically applies the spring brakes and preventsdolly converter air pressure loss in the event ofbreakaway or supply line failure. The spring brakecontrol valve also prevents the automatic application ofthe dolly spring brakes after the loss of dolly servicereservoir pressure while allowing failure indication tooccur in the towing vehicle. The spring brake controlvalve is mounted directly to the air reservoir.

Figure 21Spring brake control valve - sectioned view.

62. Charging. Air from the supply line enters thecontrol port and moves the control piston into contactwith the control port inlet and exhaust valve, sealing offthe exhaust passage through the control piston, andopening the inlet. Air entering the control port is alsoconducted to the underside of the pressure protectionpiston. When air pressure builds to approximately380 kPa beneath the pressure protection piston, thepiston moves against the force of the piston spring andremains open. Air flowing past the open pressureprotection valve opens the service reservoir checkvalve. Air passing through the service reservoir checkvalve, flows through the service reservoir port to thereservoir. It also opens the spring brake check valveallowing some air to flow by the open control inletvalve, out the delivery ports of the spring brake controlvalve, into the spring brake ports, thereby releasing thespring brakes.

Pressureprotection

piston

Pressureprotection

valve

Controlpiston

Controlport

Exhaustport

To springbrakes

Control inletvalve

Spring brakecheck valve

Reservoircheck valve

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Figure 22Spring brake control valve - charging.

63. Park application. To park the dolly converter,either the trailer valve or the parking control valve,which are located in the cab of the towing vehicle, areactuated and the dolly supply line is exhausted. Whenthe dolly supply line is exhausted, air pressure isremoved from the control and pressure protectionpistons. With air pressure removed, the control pistonis moved by the return spring, the control inlet valve isclosed and the exhaust passage through the controlpiston is opened. This allows air in the spring brakeemergency section to be exhausted through theexhaust port of the spring brake control valve. Springforce above the pressure protection piston closes thepressure protection valve. The brake reservoir checkvalve closes and protects against the loss of pressurein the reservoir.

Figure 23Spring brake control valve - park application.

Brake System Failure

64. If air pressure is reduced in the service system,pressure in the dolly supply line (and likewise in thetowing vehicle) will be reduced, until the pressureprotection piston, under spring pressure, moves andcloses the pressure protection valve. This will retainapproximately 354-415 kPa in the dolly supply line andin the towing vehicle. With 345-415 kPa pressure heldin the dolly supply line and against the control piston inthe spring brake control valve, the dolly spring brakeswill remain released. Low pressure warning will occur inthe towing vehicle to warn the driver. The spring brakecheck valve will protect against loss of air pressurefrom the reservoir which is available to keep the springbrakes released.

Figure 24Spring brake control valve - brake system failure.

65. Emergency application with service systemfailure. To brake the dolly after the service systemfailure has occurred, the dolly supply valve or parkingcontrol valve is used to exhaust the remaining 345-415kPa dolly supply line pressure. Exhausting the dollysupply line removes air pressure from the controlpiston of the spring brake control valve closing thecontrol inlet valve to seat and opening the exhaustvalve. Air from the spring brake emergency section isthen exhausted through the spring brake control valve,applying the brakes.

66. Once applied, the brakes cannot be released byair pressure until the fault has been rectified.

Yard Release Valve

67. The yard release valve is a push/pull, manuallyoperated on/off air control valve with an exhaustfunction.

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68. It is pressure sensitive and will automaticallymove from the applied to the exhaust position assupply pressure is reduced to a set minimum. (ie. 140-415 kPa).

Figure 25Yard release valve - sectioned view.

Spring Brake Chambers

69. The spring brake chamber is fitted to operate asa service brake actuator, parking brake and as anautomatic, emergency brake in the event of loss ofsupply air pressure. Air pressure is required to releasethe spring brake whilst air pressure is converselyrequired to apply the service brakes. The spring brakemay also be mechanically released by use of the springbrake release tool provided with each brake chamber.

70. Spring brake released position. Air suppliedfrom the spring brake control valve enters the spring

brake chamber through the adaptor housing and buildsup pressure below the diaphragm. When the airpressure attains sufficient force it forces the diaphragmand pressure plate, against spring pressure, into thereleased position. The adapter and brake pushrodassemblies are moved into the released position bytheir respective return springs thus releasing thebrakes.

71. Service brake application. As the brakecontrol air pressure is supplied to the brake relay valve,service brake air is released from the reservoir,through the relay valve to the service brake chamber.This air pressure passes through the adapter housinginto the chamber above the service brake diaphragmthus forcing the diaphragm and pushrod assemblydown and applying the brakes. The spring brake andthe adapter pushrod remain in the released position.

72. Spring brake application. As air pressure isexhausted from the air supply line to the spring brakecontrol valve, the exhaust port is opened, releasing theair from the spring brake lines and chamber. Thisallows the spring brake power spring to reassert itselfonto the pressure plate and diaphragm. This forceexerted by the spring brake power spring is appliedthrough the adapter pushrod to the brake pushrodassembly, compressing their respective return springsand applying the brakes.

73. Mechanical release. The spring brake may bemechanically released by using the spring brakerelease tool supplied with the brake chamber. Thespring brake release tool is engaged into the springbrake pressure plate through the access hole in thechamber housing. The brake is released as the nutsupplied with the spring brake release tool is tightenedon the threaded shaft.

Figure 26Spring brake chamber - sectioned view.

1

2

3

4

5

6

10

98

7

Item Description

1. Release bolt

2. Pressure plate

3. Adaptor pushrod

4. Adaptor housing

5. Service brake return spring

6. Pushrod assembly

7. Service brake diaphragm

8. Spring brake return spring

9. Spring brake diaphragm

10. Spring brake power spring

ReservoirportTo SR-3

Valve plate

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Slack Adjusters

74. The slack adjusters are a means of convertingthe reciprocating motion of the brake chambers intothe required rotary motion of the brake camshaftproviding a quick, and simple, method of brakeadjustment. The slack adjusters are of castconstruction with an internal worm and wheel gear setwhich provides the adjustment facility. Brakeadjustment is obtained by rotating the worm which inturn rotates the worm gear, this adjusts the position ofthe internal splines in relation to the body. Theadjustment is locked by a spring loaded locking sleeve.Refer to para 105 for the brake adjustment.

Functional Tests

75. The following tests are to be performed todetermine the presence of operating faults in the dollyconverter air brake system. Ensure that the primemover air pressure gauge is working accurately beforecarrying out these tests and that the dolly air line cocksare closed.

WARNINGBefore carrying out these testsensure that the dolly converterwheels are securely chocked.

a. Connect a 0-1000 kPa air pressure gaugeto the spare air reservoir port of the SR-3spring brake control valve.

b. Disconnect the air lines from the primemover and exhaust all air from the dollyconverter system.

c. Inspect all brake chambers to ensure thatthey are all in the applied position.

d. Inspect the condition of all air hoses andnylon lines for serviceability. Particularattention is to be given to all hose clampsand fittings.

e. Connect the air lines to the prime moverand start the prime mover engine torecharge the air brake system. Leave thetrailer service brake control and the trailerparking brake control in their respectivereleased positions.

f. As the air pressure reaches 415-445 kPathe spring brake chambers should release.Failure of all brake chambers to releaseindicates a faulty valve. Failure of individualbrake chambers to release indicates afaulty brake chamber or air line.

g. Allow the prime mover to build up full airpressure, then shut down the engine.Inspect all components for air leaks.Substantial leaks will be audible, howeverminor leaks may be detected by coatingsuspected areas with soapy water.

h. Disconnect the supply (emergency) linefrom the prime mover. This will cause thespring brakes to apply. Failure of all brakechambers to apply indicates a faulty valve.Failure of individual brake chambers toapply indicates a faulty brake chamber orair line.

i. Connect the dolly supply line to the primemover. The spring brakes should againrelease as pressure increases.

j. Open the air tank drain valve on the rearair tank The air pressure in the primemover should not fall below 354 kPa inthe prime mover air brake system. Apressure below this value indicates afaulty SR-3 spring brake control valve Thespring brakes should remain released.Application of any spring brake indicatesa faulty SR-3 spring brake control valve.Allow the air pressure in the prime moverto build up to normal between tests.

k. Open the drain valve on the front air tankof the dolly converter. When the airpressure has dropped to the minimumpressure attained in the previous test,apply the service brakes and release.Two applications of the service brakesshould be possible.

l. Allow the air pressure to return to normaland apply the service brakes. The failureof all brake chambers indicates a faulty R-12 or R-8 relay valve. Failure of individualbrakes to apply indicates a faulty brakechamber; brake hose or insufficientservice line pressure.

m. Disconnect the dolly converter air linesfrom the prime mover. Push in the yardrelease valve to release the springbrakes. Ensure that all spring brakes arereleased. Failure to do so indicates afaulty yard release valve.

n. Drain the air from the air tanks and notethe pressure at which the yard releasevalve dumps the air pressure from thespring brakes. This should beapproximately 340 kPa. Failure of the air

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pressure to be dumped indicates a weakor broken spring in the yard releasevalve.

o. Connect the air lines between the dollyconverter and prime mover and allow thesystem to be fully pressurised. Releasethe spring brakes and apply the servicebrakes.

p. Disconnect the emergency (supply) line/sbetween the dolly converter and primemover.

q. Liberally coat all joints and connectionswith soapy water and inspect for leaks.Valve body leaks should not be allowed.Bubbles in excess of 25 mm in 5 secondsshould not be allowed.

r. Apply soapy water to the emergency lineglad hand and inspect for leaks from theemergency line. A bubble in excess of 25mm in 5 seconds indicates a faulty yardrelease valve.

s. Push the yard release valve in to releasethe spring brakes. Apply soapy water tothe emergency line glad hand and inspectfor leaks from the emergency line. Abubble in excess of 25 mm in 5 secondsalso indicates a faulty yard release valve.

Air Control Systems - Precautions

76. When working on or around air brake systemsand components, the following precautions should beobserved:

a. Always block vehicle wheels. Keep handsaway from chamber push rods and slackadjusters; they may apply as systempressure drops.

b. Never connect or disconnect a hose orline containing air pressure. It may whipas air escapes. Never remove acomponent or pipe plug unless you arecertain all system pressure has beendepleted.

c. Never exceed recommended air pressureand always wear safety glasses whenworking with air pressure. Never look intoair jets or direct them at anyone.

d. Never attempt to disassemble acomponent until you have read andunderstand recommended procedures.

WARNINGSome components contain powerfulsprings and injury can result if notproperly disassembled. Use onlyproper tools and observe allprecautions pertaining to use ofthose tools.

Brake Relay Valves

77. Removal.

a. Block and hold the dolly converter bymeans other than the air brakes.

b. Drain the air system reservoir/s.

c. Tag all air lines connected to the valve tofacilitate installation.

d. Disconnect the air lines from the valve.

e. Remove the valve from the reservoir.

Figure 27Brake relay valve mounting.

NOTEPrior to disassembly mark the locationof the top cover to the body.

78. Disassembly.

a. Remove the four screws (6) securing thetop cover (1) to the body (5). Refer toFigure 28.

b. Remove the cover (1) and ‘O’ ring (2)from the body (5).

Reservoir

Control line

Relayvalve

To brakechambers

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c. Remove the valve piston (3) and ‘O’ ring(4) from the body.

d. While depressing the valve poppet guide(12), remove the circlip (14) and slowlyrelax the spring (10) beneath the valvepoppet guide.

e. Remove the valve poppet guide assemblyand ‘O’ ring.

f. Remove the inlet/exhaust valve returncompression spring (10) from the body.

g. Remove the inlet/exhaust valve poppet(8) from the body.

h. Remove the valve retainer (9) from theinlet/exhaust valve poppet.

79. Cleaning and inspection. Wash all parts inmineral spirits; wipe all rubber parts dry. Inspect allparts for signs of wear and/or deterioration. Inspectsprings for cracks, distortion or corrosion, replace ifany defects exist.

80. Inspect inlet seat and exhaust seat for nicks andburrs and replace as necessary. It is recommendedthat all rubber parts be replaced, and that any partsshowing signs of wear or deterioration be replaced.

81. Reassembly. Prior to reassembly, allcomponents should be given a light coating of SiliconePneumatic Grease - XG 315.

NOTEAll torques specified in this manual areassembly torques and can beexpected to fall off after assembly. DONOT RETORQUE after initial assemblytorques fall. For assembly handwrenches are recommended.

a. Install large piston ‘O’ ring (4) on valvepiston (3).

b. Install inner and outer ‘O’ rings (11 & 13)in the valve poppet guide assembly (12).

c. Install the sealing ring (2) on the cover(1).

d. Install valve piston (3) in body, takingcare not to damage the piston ‘O’ ring.

e. Noting the reference marks made duringdisassembly, install the cover on thevalve body and the mounting brackets onthe cover.

f. Secure the mounting bracket and coverto the body using the four cap screws (6)and lock washers (7). Torque tospecifications.

g. Install the valve retainer (9) on theinlet/exhaust valve poppet (8) and installin the body.

Figure 28Brake relay valve - exploded view.

6

8

7

9

10

11

12

13

14

1

2

3

4

5

Item Description

1. Cover

2. ‘O’ ring

3. Valve piston

4. ‘O’ ring

5. Valve body

6. Cover bolt

7. Spring washer

8. Inlet and exhaust valve poppet

9. Valve retainer

10. Compression spring

11. ‘O’ ring

12. Valve poppet guide

13. ‘O’ ring

14. Circlip

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h. Install the inlet/exhaust valve returncompression spring (10) in the body.

i. Install the valve poppet guide assembly inthe body taking care not to damage the‘O’ ring.

j. While depressing the valve poppet guide(12), install the circlip (14). Make certainthe circlip is completely seated in itsgroove in the body before releasingpressure on the spring.

82. Installation

a. Clean all air lines to be connected to thevalve.

b. Inspect all lines and/or hoses for damageand replace as necessary.

c. Install the valve to the air reservoir.

d. Connect the respective air lines to thevalve.

e. Test the valve as outlined in “FunctionalTests” in para 75.

Spring Brake Control Valve

83. Removal

a. Block the dolly converter wheels andcompletely drain the air systemreservoirs.

b. Disconnect all supply, delivery, andexhaust lines at the dolly converter springbrake valve.

NOTEMark all air lines and their relation tothe spring brake valve forreconnection.

c. Remove the spring brake valve from thedolly converter brake reservoir.

84. Disassembly

a. Remove the four round headed machinescrews (4) which secure the cover (6) tothe valve body (33). Refer to Figure 30.

Figure 29Spring brake control valve mounting.

WARNINGTake care when removing the springretainer as it is spring loaded.

b. Remove the spring (7) and pressureprotection piston assembly (8).

c. Remove the piston ‘O’ ring (10).

CAUTIONDo not attempt to remove theretaining ring and stem from thepressure protection piston.

d. Note and mark the position of the controlpiston cover (16) on the valve body.Remove the four 11/4 x 1/4 in. hexagonhead screws (14) which retain the coverto the body.

e. Remove the cover (16), control pistonassembly (18) and spring (11) from thevalve body.

f. Remove the three ‘O’ rings (12 & 13)from the control piston (18).

g. Remove the adapter (22) from the valvebody.

h. Remove the ‘O’ ring (29) from theadapter.

To air reservoir

Control line

Airreservoir

To springbrake

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Item Description Item Description

1. Pressure protection piston 18. Control piston

2. Pressure protection valve 19. Screw

3. Circlip 20. Washer

4. Cover screw 21. Exhaust diaphragm

5. Spring washer 22. Adaptor body

6. Cover 23. Check valve

7. Spring 24. Spring

8. Pressure protection piston 25. Retainer

9. Spring 26. Circlip

10. ‘O’ ring 27. Spring

11. Spring 28. Inlet/exhaust valve

12. ‘O’ ring 29. ‘O’ ring

13. ‘O’ ring 30. Plug

14. Cover screw 31. Spring

15. Spring washer 32. Check valve

16. Control piston cover 33. Valve body

17. Gasket

Figure 30Spring brake control valve - exploded view.

7

30

6

8

9

10

1

2

331

32

33

32

31

30 21

2019

18

1716

1514

2928

2726

2524

23

22

131211

45

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i. Remove the inlet valve spring (27) andinlet/exhaust valve (28).

j. Remove the screw (19), washer (20) anddiaphragm (21) from the exhaust port.

k. Remove the two 3/8 in. socket head pipeplugs (30) which retain the two singlecheck valves (32) in the body.

l. Remove the two check valve springs (31),spring guides and rubber check valves(32).

85. Cleaning and inspection

a. Wash all metal parts in mineral spirits anddry them. Inspect all parts for excessivewear or deterioration.

b. Inspect the valve seats for nicks or burrs.

c. Check the springs for cracks or corrosion.

d. Replace all rubber parts and any part notfound to be serviceable during inspection.

86. Reassembly

NOTEPrior to reassembly of the valve.Lubricate all ‘O’ rings, ‘O’ ring grooves,piston bores and metal to metalmoving surfaces with SiliconePneumatic Grease - XG 315.

a. Assemble the spring (31) to each of thecheck valves (32) with a twisting motion.

b. Fit the assemblies into their respectivebores in the valve body and install the 3/8in. pipe plugs (30).

c. Insert the flat rubber inlet/ exhaust valve(28) into the valve body.

NOTEThe flat side of the valve with the four"ears" protruding rests against the inletand exhaust valve seat.

d. Install the inlet/exhaust valve spring (27).Ensure that the spring is aligned andrests evenly on the four "ears" of the inlet/exhaust valve (28).

e. Install the ‘O’ ring (29) in its propergroove on the reservoir port adapter (22).

f. Correctly align the inlet/exhaust valvespring in the recess at the end of thereservoir port fitting. Install the fitting andtorque to specifications.

g. Install the three ‘O’ rings (12 & 13) in theirrespective grooves on the control piston(18).

h. Position the piston spring (11) into thevalve body.

i. Install the control piston (18) in the valvebody.

j. Refit the control piston cover (16),complete with new gasket (17), in itscorrect position. The screws (14) shouldbe torqued to specifications.

k. Install the screw (19), washer (20) andexhaust diaphragm (21) in the controlpiston exhaust port. Torque the screw tospecifications.

l. Install the ‘O’ ring (10) in the respectivegroove of the pressure protection piston(8). Install the piston assembly in thevalve body.

m. Position the spring (7) and cover (6) ontop of the pressure protection pistonassembly, and secure with the four roundhead machine screws (4). Screws shouldbe torqued to specifications.

87. Installation

a. Clean the air lines to be connected to thevalve.

b. Inspect all lines and/or hoses for damageand replace as necessary.

c. Fit the valve to the air reservoir.

d. Connect the air lines to the valve.

e. Test the valve as outlined in “FunctionalTests” in para 75.

Pilot Relay Valve

88. Removal

a. Block or hold the vehicle by means otherthan the brakes.

b. Drain all air brake system reservoirs.

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c. Identify, mark, and disconnect all air linesfrom the valve.

d. Remove the valve from its mounting.

89. Disassembly. Prior to disassembly of the valvemark the relationship of the cover and body to facilitateassembly. Refer to Figure 31.

a. Remove the four 5/16 in. hex head capscrews and lock-washers that secure thecover (1) to the body (7) and separate thevalve halves.

b. Remove the ‘O’ ring (6) from the groovein the body.

c. Remove the relay piston (5) and ‘O’ ring(3) from the cover.

d. Remove the exhaust port cover.

e. Remove the screw that secures theexhaust diaphragm (18) and washer tothe exhaust cover.

f. Remove the four screws that secures theexhaust cover (17) to the body.

g. Remove the inlet/exhaust valve insertfrom the body.

NOTE If a new inlet/exhaust valve insert is tobe installed, omit step h.

h. Disassemble the insert by removing theretaining ring and separating; the specialwasher (16), ‘O’-rings (13 & 15), the valvespring (12), valve retainer (11) and thepoppet valve (10).

Figure 31Brake pilot relay valve - exploded view.

Item Description

1. Cover

2. Spring

3. ‘O’ ring

4. ‘O’ ring

5. Relay piston

6. ‘O’ ring

7. Body

8. Spring washer

9. Screw

10. Poppet valve

11. Retainer

12. Spring

13. ‘O’ ring

14. ‘O’ ring retainer

15. ‘O’ ring

16. Special washer

17. Exhaust cover

18. Exhaust diaphragm

19. Washer

20. Screw

21. Spring washer

22. Screw

10

11

12

13

15

1

2

3

4

5

14

16

17

18

192221

9

8

7

6

20

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90. Cleaning and inspection

a. Wash all metal parts in mineral spirits anddry them thoroughly.

NOTEWhen rebuilding the valve all springsand all rubber parts should be replaced.

b. Inspect all metal parts for deteriorationand wear, as evidenced by scratches,scoring and corrosion.

c. Inspect the exhaust valve seat on therelay piston for scratches and nicks,which could cause excessive leakage.

d. Inspect the inlet valve seat in the body forscratches and nicks, which could causeexcessive leakage.

e. Replace all parts not consideredserviceable during these inspectionsincluding all springs and rubber parts.

91. Reassembly. Prior to reassembling the valve,lubricate all ‘O’ rings, ‘O’ ring grooves, piston boresand metal to metal moving surfaces with SiliconePneumatic Grease - XG-315.

NOTEAll torques specified are assemblytorques and can be expected to fall off,after assembly. Do not retorque afterinitial assembly torques fall.

92. For assembly, hand wrenches are recommended.

a. Install the ‘O’ ring on the service port capnut.

b. Install the quick release port cover usingone of the Phillips head screws. Thescrews should be torqued tospecifications.

c. Install the ‘O’ ring (3) on to the relaypiston (5) and install the piston in thecover (7).

NOTEIf a new inlet/exhaust valve insert isused, omit steps d to g

d. Place the poppet valve (10), rubber sidedown, on a clean flat surface. Install thevalve retainer (11) then the spring (12) onthe poppet valve.

e. Install the two ‘O’ rings (13 & 15) in theirappropriate grooves in the ‘O’ ringretainer (14) and place the special washer(16) over the ‘O’ rings.

f. While holding the ‘O’ ring retainer andspecial washer together, install them overthe poppet valve (10), making sure theinlet valve spring (12) is bearing on the‘O’ ring retainer.

g. Install the retainer ring in the groovearound the poppet valve (10) whileholding the assembly compressed.

h. Install the inlet/exhaust valve insert in thebody bore.

i. Place the exhaust cover (17) on the bodyand secure it using the four Phillips headscrews (22). The screws should betorqued to specifications.

j. Place the exhaust diaphragm (18) on theexhaust cover and secure it using thediaphragm washer and the remainingPhillips head screw. The screw should betorqued to specifications.

NOTEPrior to assembling the cover to thebody, note the mark made duringdisassembly to obtain the propercover/body relationship.

k. Install the ‘O’ ring (6) in the groove of thevalve body and join the two valve halvestogether.

l. Secure the body to the cover using thefour 5/16 in. hex head cap screws. Thescrews should be torqued tospecifications.

93. Installation. Prior to installing the valve, allconnecting air lines should be inspected for kinks,cuts, chafing and deterioration. Repair or replace asnecessary.

a. Mount the valve securely.

b. Connect all air lines to the correct ports,using the identification markings of thelines made before the valve wasremoved.

c. Test all reconnected air line fittings forleakage.

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d. Test the valve as outlined in “FunctionalTests” in para 75.

Yard Release Valve

94. Removal. Block and/or hold the dolly converterby a means other than the air brakes. Drain allreservoirs.

a. Drive the button roll-pin out with a punchand remove the button.

b. Disconnect the air lines, remove thepanel mounting nut and remove thevalve.

95. Disassembly

a. Remove the two cap screws (14) whichretain the lower cover (12) and removethe cover. Remove the sealing ring (11).Refer to Figure 32.

b. Insert a small punch through the roll pinhole in the plunger stem and remove thelocknut (10).

c. Remove the inlet/exhaust valve (8),plunger (3) and spring (5).

d. Remove the ‘O’ ring (4) from the plunger (3).

96. Reassembly

NOTEPrior to reassembly of the valve lubricateall ‘O’ rings, ‘O’ ring grooves and metalto metal moving surfaces with SiliconePneumatic Grease - XG 315.

a. Fit the ‘O’ ring (4) to the plunger (3).

b. Fit the spring (5), plunger (3) andinlet/exhaust valve (8).

c. Insert a small punch through the roll pinhole in the plunger stem, fit the flatwasher (9) and locknut (10).

d. Fit the sealing ring (11) and lower cover(12). Secure with the two hexagonheaded screws (14).

97. Installation

a. Install the valve in the mounting bracket,securing with the panel mounting nut.

b. Re-connect the air lines.

c. Install the operating button (1). Securethe operating button by installing the rollpin (2).

Figure 32Yard release valve - exploded view.

Item Description

1. Button

2. Roll Pin

3. Plunger

4. ‘O’ ring

5. Spring

6. Panel mounting nut

7. Body

8. Inlet/Exhaust valve

9. Washer

10. Locknut

11. Sealing ring

12. Lower cover

13. Spring washer

14. Screw

1

2

3

4

6

5

7

89

10

11

1213

14

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Spring Brake Chamber

98. Removal. Refer to Figure 33.

a. Remove the plastic plug from the springbrake chamber housing.

b. Remove the spring brake release toolfrom the chamber body and insert it intothe spring brake chamber, passing itthrough to the centre of the spring brakepressure plate.

NOTEPrior to inserting the spring brakerelease tool into the chamber fit the flatwasher and nut to the end of the tool.

c. Rotate the spring brake release tool 90o

to engage the lugs into the pressureplate.

d. Screw the nut onto the spring brakerelease tool, withdrawing the spring brakerelease tool from the housing. Thiscompresses the spring brake powerspring, releasing the brake.

e. Remove the two air hoses from the brakechamber, ensuring that each line isidentified to ensure correct installation.

f. Remove the cotter pin (27) and clevispins (26) connecting the clevis assemblyto the slack adjuster.

g. Remove the clevis (25) from thepushrod (21).

h. Remove the two nuts and washers fromthe mounting bracket.

99. Disassembly. Refer to Figure 33. Prior todisassembly of the spring brake chamber ensure thatthe spring brake power spring is fully caged. Use thespring brake release tool assembly normally fitted tothe boss on the side of the adapter housing. When thespring is fully caged, dismantle the spring brakechamber in the following sequence:

WARNINGExtremely high spring pressures existwithin the spring brake chamber.Complete disassembly should not beattempted unless adequate facilitiesare available for the removal of thecompression spring.

a. Mark the correct alignment of thehousings and clamp assemblies to ensurecorrect alignment on reassembly.

b. Remove the clevis assembly from therod.

c. Remove the vent tube (14) and rubberelbows (13).

d. Remove the clamp (12) securing thepressed metal cover (23) to the adapterhousing (18).

e. Remove the pressed metal housing (23),service brake return spring (22), thepushrod assembly (21) and the servicebrake diaphragm (20) from the adapterhousing (18).

f. Remove the clamp securing the springbrake housing (1) to the adapter (18).

g. Lift the adapter housing from the springbrake housing and remove the springbrake diaphragm (5).

h. Place the spring brake housing andspring assembly into a suitable press,approximately 380 mm. of ram travel isrequired to fully release the springpressure. Ensure that adequate access isavailable to undo the release studassembly.

i. Take the spring pressure with the pressand remove the nut from the spring brakerelease tool. Slowly release the pressallowing the spring to extend to fullextension. Remove the spring (3) andhousing (1) from the press.

j. Place the adapter housing (18) in thepress with the compression spring (8) onthe upper side. Apply sufficient pressureonly to clamp the upper plate against theadapter housing.

CAUTIONDo not apply excessive pressure asdamage to the adapter housing mayresult.

k. Remove the lower of the two nylonscrews (6) and the respective plate (7)from the adaptor pushrod (11).

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Figure 33Spring brake chamber - exploded view.

Item Description Item Description Item Description

1. Spring brake housing 11. Adaptor pushrod 21. Pushrod

2. Spring seat 12. Clamp 22. Service brake return spring

3. Spring 13. Vent tube elbow 23. Housing

4. Pressure plate 14. Vent tube 24. Hexagon nut

5. Spring brake diaphragm 15. Clamp screws 25. Clevis

6. Screw 16. Red tag 26. Clevis pin

7. Retainer 17. Clamp screw nuts 27. Cotter pin

8. Return spring 18. Adaptor housing 28. Hexagon nut

9. Pushrod guide 19. Washer 29. Spring washer

10. Seal 20. Service brake diaphragm

18

19

12

6

17

20

21

22

23

24

13

15

25

2627

2928

12

9

11

109

8

76

5

4

3

2

1

13

14

15

1617

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l. Release the press and allow the spring(8) to extend to it’s full length.

m. Remove the adapter pushrod (11) andspring (8).

n. Remove the two nylon bushes (9) and theneoprene seal (10) from the adapterhousing (18).

100. Cleaning and inspection. Thoroughly wash allmetal components in a suitable solvent and blow drywith compressed air. Inspect all components asfollows:

a. Inspect the clevis assembly for any wearor damage and discard if necessary.

b. Inspect the push rod assembly for bendsor excessive wear, straighten or replaceas necessary.

c. Inspect the pressed metal housing forevidence of cracks or metal fatiguearound the mounting studs and theclamping flange. Discard and replace ifany evidence exists.

d. Inspect the adapter housing for cracks orsigns of wear, particularly around theclamping flanges and the centre pushrodboss. Discard if wear or cracking isevident.

e. Inspect the spring brake housing for wearor cracks, particularly around theclamping flange and the rear face.Discard if any wear, cracking or otherdamage is evident.

f. Inspect all springs for serviceability,replace if necessary.

g. Inspect the adapter pushrod for wear orother damage to the sealing surface,discard and replace if any exists.

h. Inspect the spring brake pressure platefor wear or damage, particularly aroundthe centre boss area where the releasestud assembly engages. Discard if anysigns of wear or other damage exists.

i. Inspect the clamps, screws and nuts forwear or damage, discard if any exists.

j. Inspect the diaphragms for any signs ofperishing or other damage. Inspect theouter edges for build up of rust and scale,

remove if the diaphragm is otherwiseserviceable, discard if any flaws arefound.

NOTEIt is normally considered good practiceto replace the diaphragms duringoverhaul if possible. Refit olddiaphragms only if totally satisfied oftheir serviceability.

101. Reassembly

NOTEDuring reassembly of the spring brakechamber, the adapter pushrod, seal,nylon bushes and the edges of thediaphragms should be given a light filmof Silicon Pneumatic Grease - XG 315.

a. Fit the seal (10) and nylon bushes (9) tothe adapter housing (18) ensuring thatthey have a light film of lubricant.

b. Mount the adapter housing (18) onto thepress bed with the spring brake side up.Place the return spring (8) in position inthe adapter housing followed by theadapter pushrod (11).

c. Using the press, slowly compress thespring ensuring that the adapter pushrodis correctly aligned with the centre boss ofthe adapter housing. Press until the plateis clamped between the press and theadapter housing.

CAUTIONDo not apply excessive pressure asdamage to the adapter housing mayresult.

d. Fit the retaining plate (7) and the screw(6) to the adapter pushrod and releasethe press slowly.

NOTEThe screws fitted to the adapterpushrod are supplied with a Loctitecoating. If refitting used screws theyare to be coated with Loctite 272.

e. Place the spring brake housing (1),compression spring (3), pressure plate (4)and spring seat (2) respectively onto thepress bed.

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f. Slowly compress the compression springensuring that the spring brake releasetool is aligned with the aperture in theadapter housing. When the spring is fullycompressed fit the nut to the spring brakerelease tool.

g. Remove the spring brake housingassembly from the press and fit thediaphragm (5) to the housing.

h. Fit the adapter housing (18) to the springbrake housing (1).

i. Fit the clamp assembly (12) to the twohousings ensuring that it is correctlyaligned. Tighten the two clamp screwsevenly.

j. Fit the service brake diaphragm (20) tothe adapter housing (18) ensuring that alight film of lubricant has been applied tothe outer edges of the diaphragm.

k. Place the push rod assembly (21) inposition on the diaphragm and slide thereturn spring (22) in position on thepushrod.

l. Slide the pressed metal housing (23) overthe pushrod and align it with the otherhousings. Fit the remaining clamp inposition, ensuring that it is correctlyaligned. Tighten the clamp bolts evenly.

m. Fit the clevis assembly (25) and locknut(24)to the push rod.

102. Installation

a. Ensure that the spring brake compressionspring is fully caged by the spring brakerelease tool.

b. If not already fitted, fit the two hose stemsto the chamber adapter housing.

c. Fit the brake chamber to the mountingbracket and secure with the respectivehexagonal nuts and washers.

d. Fit the clevis assembly and locknut to thepush rod. Ensure that it is correctlypositioned and aligned. Tighten thelocknut.

e. Connect the clevis to the slack adjuster.

f. Connect the two air hoses ensuring thatthey are connected to the correct ports.

g. Remove the spring brake release toolfrom the spring brake chamber housingand replace it into the stowage boss.

h. Fit the plastic plug into the spring brakehousing.

i. Fit the vent tube and rubber elbows.

j. Check the brake adjustment and adjustas required. Refer to para 105.

Wheel Brake Assembly

103. Disassembly. Refer to Figure 34.

a. Remove the spring brake chamber asdetailed in para 98.

b. Remove the wheel hub and brake drumassembly as detailed in para 17.

c. Move the slack adjuster and camshaftinto the fully released position.

d. Remove the two circlips (5) securing thebrake shoe anchor pins (10).

e. Slide the two anchor pins (10) from thebrake shoe mountings, remove the brakeshoes (2) and separate them from thereturn spring (6).

f. Remove the cam rollers (8) and retainingclips (7) from the brake shoes.

g. Refer to Figure 35 from here onwards.Remove the slack adjuster retainingcirclip (1) from the inner end of thecamshaft (16). Slide the slack adjuster (3)from the camshaft splines.

h. Remove the circlip securing the camshaftto the brake mounting plate.

i. Slide the camshaft from its mountingswhilst sliding the circlip and flat washerfrom the camshaft.

j. Remove the four hexagon headed screwsand nuts securing the camshaft nylonbushing (8). Remove the bushing andsteel housings (6).

k. Remove the two camshaft seals (13) fromthe brake mounting plate.

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Figure 34Wheel brake assembly - exploded view.

Figure 35Brake camshaft and mountings - exploded view.

Item Description

1. Bolt

2. Brake shoes

3. Anchor pin bush

4. Flat washer

5. Circlip

6. Return spring

7. Spring clip

8. Cam roller

9. Spring retainer

10. Anchor pin

11. Brake drum

12. Spring washer

13. Hexagon nut

Item Description

1. Circlip

2. Flat washer

3. Slack adjuster

4. Grease nipple

5. Bolt

6. Steel housing

7. ‘O’ ring

8. Nylon bushing

9. Grease nipple

10. Washer

11. Nut

12. Bracket

13. Seal

14. Bushing

15. Steel plate

16. Camshaft

7

8

910

45

1213

1

54

3

2

2

11

6

1

51

12

6

78

7

2

6

10

9

3

2

4

1314

1315

16

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l. If required, the bushings may be removedfrom the brake shoe and camshaft pivotsin the brake mounting plate.

104. Reassembly. Refer to Figure 35.

a. Fit the bushes to the bush mountingplate.

b. Fit the camshaft seals (13) to the brakemounting plate.

NOTEEnsure that the seals are correctlyfitted and facing the correct direction.The lip of the outer seal is to face intothe brake mounting plate to preventgrease entering the brake assemblywhilst the lip of the inner seal facestowards the centre line of the dollyconverter. This will allow excessgrease to escape whilst preventing theentry of dirt and moisture.

c. Install the nylon bushing (8) and housings(6). Do not tighten the mounting screws (5).

d. Fit the camshaft (16) to the mountingplate and slide it through the nylon bush.A circlip and flat washer are to be fitted tothe camshaft before fitting through thenylon bushing.

e. Tighten the four nylon bush mountingscrews. Check for free rotation of thecamshaft.

f. Fit the slack adjuster (3) to the camshaftensuring that the adjusting screw isfacing away from the spring brakemounting plate and fit the flat washer andretaining circlip. Rotate the camshaft tothe fully released position.

g. Refer to Figure 34 from here onwards.Fit the cam rollers (8) and retaining clips(7) to the brake shoes.

h. Fit the return spring (6) to the two brakeshoes and slide the brake onto themounting plate.

i. Fit the brake shoe anchor pins (10), flatwashers (4) and circlips (5).

j. Fit the brake drum and hub assembly asdetailed in para 28.

k. Fit the spring brake chamber as detailedin para 102.

l. Grease the camshaft bushes and slackadjuster.

Brake Adjustment

105. Correct adjustment is obtained when the angleformed by the centre lines of the slack adjuster andthe brake chamber pushrod is just over 90 degreeswhen the brakes are applied.

106. Adjustment. To adjust the brakes depress thelocking ring around the adjusting screw and using a9/16 in. AF wrench turn the adjusting screw. Rotatingthe screw clockwise applies the brakes andanticlockwise releases the brakes.

Figure 36Brake adjustment.

Released

Applied

AdjusterServicebrake

chamber

Springbrake

chamber

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FAULT FINDING

Table 4

Symptom Probable Cause Action

1. Insufficient braking a. Mechanical components damaged a. Check for damaged parts, replaceas required

b. Worn brake linings b. Replace brake liningsc. Low pressure in the brake system c. Check supply pressure from the

towing vehicled. Reservoir drain cock open d. Close drain cock

2. Brakes apply tooslowly

a. Brakes require adjusting orlubrication

a. Adjust brakes, lubricate brakecomponents.

b. Relay valve faulty b. Replace valvec. Blocked or restricted air lines/hoses c. Clear blockage. Replace air line or

hosed. Leaking brake chamber diaphragm d. Replace brake chamber

3. Brakes release tooslowly

a. Brakes require adjusting orlubrication

a. Adjust brakes, lubricate brakecomponents

b. Relay valve faulty b. Replace valvec. Blocked or restricted air lines/hoses c. Clear blockage. Replace air line or

hose

4. Brakes do notrelease

a. Brake shoe return spring weak orbroken

a. Replace spring

b. Spring brake chamber diaphragmfaulty

b. Replace brake chamber

c. Faulty spring brake control valve orrelay valve

c. Replace faulty valve

5. Brakes grab or are a. Oil or grease on brake linings a. Replace brake liningserratic b. Faulty brake chambers b. Replace faulty brake chambers

c. Eccentric brake drum(s) c. Replace brake drum(s)d. Loose brake lining d. Re-line brake shoese. Brake shoe return spring weak or

brokene. Replace spring

6. Uneven braking a. Oil or grease on brake linings a. Replace brake linings and oil orgrease seal

b. Eccentric brake drum(s) b. Replace brake drum(s)c. Brake chamber diaphragm leaking c. Replace brake chamber

7. Spring brake does a. Power spring broken a. Replace brake chambernot hold b. Brakes require adjusting b. Adjust brakes

c. Faulty SR-3 valve c. Replace valve

8. Brakes drag afterspring brakes have

a. Low spring brake hold off airpressure

a. Check air pressure in system

been used b. Leaking air lines b. Repair leaks

9. Spring brakes will a. Insufficient air pressure a. Check air pressure in systemnot release b. Faulty SR-3 valve b. Replace valve

c. Spring brake chamber diaphragm faulty c. Replace brake chamber

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SPECIFICATIONS

Relay valve upper cover screws torque............................................................................ 9-14 Nm (80-120 lb in)

Spring brake control valve to reservoir adapter torque ................................................. 23-34 Nm (200-300 lb in)

Spring brake control valve control cover screws torque........................................................ 5-7 Nm (40-60 lb in)

Exhaust diaphragm screw torque ........................................................................................... 2 Nm (15-20 lb in)

Pressure protection piston cover screw torque .................................................................... 2-3 Nm (20-30 lb in)

Pilot relay valve quick release port cover screws torque....................................................... 2-3 Nm (20-30 lb in)

Pilot relay valve exhaust cover screws torque ...................................................................... 2-3 Nm (20-30 lb in)

Pilot relay valve exhaust diaphragm cover screw torque ..................................................... 0.5-1 Nm (5-10 lb in)

Pilot relay valve cover/body screws torque....................................................................... 9-14 Nm (80-120 lb in)

Brake chamber clamp torque ...................................................................................................... 35 Nm (25 lb ft)

Maximum brake chamber pushrod travel ..................................................................................................40 mm

Brake chamber to clevis centre line .......................................................................................................185 mm

Maximum operating air pressure..............................................................................................900 kPa (130 psi)

END

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SUSPENSION - GROUP 13

General

107. The dolly converters use two different designsof suspension, namely the equaliser type suspensionand the single point suspension.

108. The axles on the equaliser type suspensionunits are carried by 10 leaf, semi-elliptic springs,which are located onto load equalisers at either end.Two springs are provided for each axle assembly.The axle assemblies are each located by a pair ofradius rods required to maintain correct axlealignment whilst still allowing full spring deflection.

109. The axles on the single point suspension unitsare carried by 12 leaf, semi-elliptic springs which arecentrally located on a support tube and mountingbracket. Only one overhung spring is provided foreach side of the axle assemblies and the need forradius rods has been dispensed with due to thedirect location of the axle clamps to the springs.

Equaliser Suspension

110. Description. The equaliser suspension unituses an Engineered Transport Equipment 1.4 metre,overslung leaf spring type suspension. Load sharingcapabilities are provided by the use of the centremounted equaliser assembly. The springs are of 10leaf, semi-elliptic construction and are free to slide intheir respective hangers at either end. The axles arelocated by means of radius rods which allow freemovement of the axles for the full length of thesuspension while still maintaining correct axlealignment.

111. Springs. The springs are 10 leaf, semi-elliptic, sliding shackle type fixed to the axleassemblies by steel ‘U’ bolts and located by caststeel spring seats welded to the axle assembly. The

third leaf of each spring assembly has one endfolded down in a vertical position. This end of thespring is fitted into the equaliser assembly andprevents the spring from becoming dislodged fromthe equaliser.

112. Spring hangers. The spring hangers are caststeel, front and rear, welded to the dolly converterframe. They are moulded to accept the curvature ofthe leaf springs which are free to slide within thespring hangers as required by the suspension action.The springs are retained within the spring hangersby a bolt fitted across the spring hanger.

113. Equaliser assembly. The equaliser assemblyprovides the load sharing capabilities of the ETEsuspension. The equaliser assembly consists of acentre, cast steel, equaliser hanger carrying a caststeel equaliser beam which is pivoted on two taperedrubber bushes. As with the spring hangers, thesprings are free to slide in the equaliser beam andare held in position by a single bolt.

114. Radius rods. The radius rods used in thisapplication are divided into two separate types.These are:

a. Fixed length rods. These are of castconstruction moulded to accept taperedrubber bushes in each end.

b. Adjustable rods. The two adjustablerods each consist of a steel hexagonalrod threaded each end with left and righthand threads, and one each of left andright hand threaded cast steel endsmoulded to accept tapered rubber bushesand associated clamping bolts with nylocnuts.

Figure 37Equaliser suspension layout.

Front spring hanger Equaliser assembly Rear spring hanger

Fixed radius rod

Axle assembliesAdjustable radius rod

Spring

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Equaliser Assembly

115. Bush replacement. Support the weight of thedolly converter frame, leaving the axle assembliesresting on the ground or supported. All weight is to beoff the suspension components. Refer to Figure 38.

a. Remove the centre bolt and nut (7 & 2),flat washer (3) and equaliser shaft (6)from the equaliser beam (5).

b. Whilst supporting the equaliser beam,remove the two tapered rubber bushes(4) from the equaliser hanger and beam.

c. Fit replacement bushes to the hanger andequaliser beam.

d. Fit the equaliser shaft, flat washer, centrebolt and nyloc nut. Tighten to thespecified torque.

NOTEThe bolts are to be fitted from insidethe dolly converter frame.

116. Removal of equaliser beam.

a. Support the dolly converter frame onsuitable stands.

b. Remove the equaliser shaft (6) andbushes (4) as detailed above in para 115.

c. Remove the two hexagonal headedretainer bolts (8) from the equaliserbeam.

NOTETo remove the equaliser beam it maybe necessary to lower the axles furtheraway from the frame or to remove onespring assembly as detailed in para120. This will be dependent on theclearance left between the spring andthe equaliser seats.

117. Installation of equaliser beam. Position theequaliser beam in the hanger ensuring that it iscorrectly positioned in relation to the spring.

a. Fit the equaliser bushes and shaftassembly as detailed in para 115.

b. If springs were removed to allow removalof the equaliser beam, replace the springas detailed in para 121.

c. Seat the spring into the equaliser and fitthe two retaining bolts (8).

Radius Rods

118. Removal. Place safety stands under the dollyconverter frame so as to remove the weight from thesuspension. Refer to Figure 39.

a. Remove the two bolts (1) securing theradius rod (5) to the spring seat (7) andthe respective spring hanger.

b. Remove the tapered bushes (3) and steelsleeve (4) from the radius rod ends.Remove the radius rod.

119. Installation.

a. Refit radius rods (5), tapered bushes (3),steel sleeves (4), washers (2), bolts (1)and nuts (6). Tighten to the specifiedtorque.

NOTEThe bolts are to be fitted from insidethe dolly converter frame.

Item Description Item Description

1. Equaliser hanger 6. Steel shaft

2. Nyloc nut 7. Bolt

3. Flat washer 8. Retainer bolt

4. Tapered bush 9. Hexagon nut

5. Equaliser Beam

Figure 38Suspension equaliser.

23

4 5

4

6

7

1

9

8

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b. Lower the dolly converter frame so thatthe suspension is taking the weight of thedolly.

c. Check and adjust axle alignment inaccordance with paras 14 - 16.

Springs

120. Removal. Support the weight of the dollyconverter frame. The wheels should be left resting onthe ground with all weight off the suspensioncomponents. Approximately 25 mm clearance shouldbe between the spring and the spring hanger seats.

a. Remove the hexagon nuts from ‘U’ boltsretaining the spring to the axle. Removethe ‘U’ bolts and spring cap.

b. Remove the hexagon headed springretaining bolts from the equaliser andspring hanger.

c. Lift the spring clear of the axle and frame.

121. Installation.

a. Position the spring on the axle spring seatensuring that the spring ends arecorrectly located in the spring hanger andequaliser beam and that the folded leafend is in the equaliser beam.

b. Fit the hexagon headed retaining bolts tothe spring hanger and equaliser beam.

c. Fit the spring ‘U’ bolts, spring cap, flatwashers and hexagon nuts. Tightenevenly to the specified torque.

Spring Hangers

122. Removal. The spring and equaliser hangersare fixed to the dolly frame by welding. They are to beremoved, if required, by grinding away the weldmaterial holding the hangers to the frame. Caution is tobe taken to prevent excessive damage to the parentmaterial.

123. Replacement. Prior to replacement all surfacesto be welded are to be free of any rust or scale, theyshould be flat and flush fitting. All welds to the top of thehanger brackets are to be 10 mm fillets. When fittingthese weld on hangers a careful check should be madeto ensure that they are correctly located and squarewith the frame. Tack weld the castings in place andrecheck the location before final welding. Weld allround.

CAUTIONDo not weld across the mainmember flanges apart from atspring hangers.

Welding

124. Refer to details in GROUP 16, para 148.

Single Point Suspension

125. Description. The single point suspension unituses an Engineered Transport Equipment SP500series, overslung leaf spring type suspension. Thesprings are 12 leaf semi-elliptic construction,attached to the dolly converter by centrally positionedmounting brackets, with an interconnecting cross-tube arrangement. Refer to Figure 40.

126. Springs. The springs are 12 leaf, semi-elliptictype fixed to the axle assemblies by steel ‘U’ boltsand located on upper axle clamps welded to the axleassembly. The springs are located on the clamps bya dowel arrangement incorporated into the upperclamps.

127. Spring hangers. The spring hanger systemconsists of mounting brackets welded to the dollyconverter frame. The brackets are clamped to aninterconnecting tube which carries the central springseats and ‘U’ bolts, thus acting as a pivot point.

Item Description Item Description

1. Bolt 5. Radius rod

2. Flat washer 6. Nyloc nut

3. Tapered bush 7. Spring seat

4. Steel sleeve

Figure 39Radius rod mounting bushes and pins.

7

623

5

43

21

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Spring Hangers

128. Bush replacement. Support the weight of thedolly converter frame, springs and axles, whilstleaving the axle assemblies resting on the ground.All weight is to be off the suspension components.Refer to Figure 41.

a. Place a jacking arrangement below theinterconnecting tube (7), to permit thetube to be lowered when disconnectedfrom the dolly converter.

b. Remove the outer cap locknuts, nuts (14)and washers (13), and lower the outercaps (12) from the mounting brackets (1)and tube.

c. Remove the centre ‘U’ bolts locknuts,nuts (11) and washers (10), and lower thetube clamp brackets (9) from the springmountings and tube.

d. Whilst supporting the spring mountings(6), slowly lower the tube (7) until therubber bushes (8) can be pulled off thetube ends.

e. Fit replacement bushes on the tube andraise the tube until it contacts the springmountings (6).

f. Position the tube clamp brackets (9) overthe ‘U’ bolts (3) and into place on thespring mountings.

g. Fit the centre ‘U’ bolts washers (10) andnuts (11). Tighten to the specified torque.Fit the locknuts and apply torque.

h. Position the outer caps (12) over the tubeand into place on the mounting brackets.

i. Fit the outer cap bolts (2), washers (13)and nuts (14). Tighten to the specifiedtorque. Fit the locknuts and apply torque.

Spring Seats

129. Rubber pad replacement. Chock the dollyconverter wheels to prevent movement whilstreplacing the rubber pads fitted to the spring ends.Refer to Figure 41.

a. Remove the spring ‘U’ bolt locknuts, nuts(29) and flat washers (28), and lower thelower axle clamps (27) from the upperaxle clamps (25).

b. Extract the spring ‘U’ bolts (22) and lift theaxle ‘U’ bolt brackets (23) off the springs,to expose the rubber pads (24).

c. Fit replacement rubber pads on thesprings and replace the axle ‘U’ boltbrackets.

d. Place the spring ‘U’ bolts in position,ensuring that all threads are inserviceable order.

e. Mount the lower axle clamps (27) on the‘U’ bolts until they enclose the axlecorrectly. Fit the flat washers (28) andnuts (29). Torque the ‘U’ bolt nuts evenlyto the specified torque. Attach thelocknuts to the ‘U’ bolts and torqueevenly.

Springs

130. Removal. Prior to removal of anycomponents of the suspension, correctly support thedolly converter frame, with all weight removed fromthe suspension components. Remove thesuspension assemblies using the followingprocedure. Refer to Figure 41.

a. Remove both axle assemblies in accordancewith Group 9, para 12.

b. Remove the ‘U’ bolts (22), axle ‘U’ boltbrackets (23) and rubber pads (24) fromthe spring ends.

c. Position a suitable jacking device beneaththe dolly converter frame, to support eachend of each spring assembly.

Figure 40Single point suspension assembly.

Axleassemblies

Mountingbracket

Spring

Axleclamps

Interconnectingtube clamps

Spring mountingclamps

Interconnectingtube

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d. Remove the locknuts, nuts (14) andwashers (13) securing the outer caps (12)to the mounting brackets (1).

e. Carefully lower both spring assembliesand connecting tube onto a suitabletrolley and transfer to a suitable locationfor further attention.

f. Remove the ‘U’ bolt locknuts, nuts (11)and washers (10) securing the tube clampbrackets (9) to the tube. Remove the tubeclamp brackets, spring mountings (6) andtube (7).

g. Slide the rubber bushes (8) off each endof the tube (7).

Figure 41Single point suspension - exploded view.

20

23

22

2119

18

24

26

25

27

28

29

8

1

2

3

4

7

6

5

9

10

12

11

13

14

15

16

17

Item Description Item Description Item Description

1. Mounting bracket` 11. Centre ‘U’ bolt nut 21. Spring clamp bolt

2. Outer cap bolt 12. Outer cap 22. Spring ‘U’ bolt

3. Centre ‘U’ bolt 13. Washer 23. Axle ‘U’ bolt bracket

4. Centre ‘U’ bolt bracket 14. Outer cap nut 24. Rubber pad

5. Spring 15. Spring centre bolt 25. Upper axle clamp

6. Spring mounting 16. Spring centre bolt nut 26. Dowel

7. Tube 17. Spring clamp nut 27. Lower axle clamp

8. Rubber bush 18. Spring clamp rivet 28. Washer

9. Tube clamp bracket 19. Spring clamp 29. Spring ‘U’ bolt nut

10. Washer 20. Spring clamp tube

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131. Installation

a. Place the centre ‘U’ bolt brackets (4) and‘U’ bolts (3) on the top of each springassembly, ensuring that all threads are inserviceable order.

b. Fit replacement bushes (8) on each endof the tube (7) and place the tube intoboth tube clamp brackets (9).

c. Locate the spring mountings (6) overeach end of the tube and line up with thetube clamp brackets (9), ensuring that therubber bushes (8) are located correctly.

d. Place each spring over their respectivespring mounting (6) and thread the ‘U’bolts (3) through the spring mountingsand tube clamp brackets.

e. Fit the centre ‘U’ bolt washers (10) andnuts (11). Tighten to the specified torque.Fit the locknuts and apply torque.

f. Position the spring asemblies under thedolly converter.

g. Using suitable jacking equipment,carefully raise the spring arrangementuntil the centre ‘U’ bolts are positionedbetween the mounting brackets (1) andthe tube ends mate with the landings inthe brackets.

h. Place the outer caps (12) over the tubeends and into position on the mountingbrackets.

i. Fit the outer cap bolts (2), washers (13)and nuts (14). Tighten to the specifiedtorque. Fit the locknuts and apply torque.

j. Remove the jacking equipment frombeneath the spring assembly.

k. Refit both axle assemblies, in accordancewith Group 9, para 13.

Spring Mounting Brackets

132. Removal. The spring mounting brackets arefixed to the dolly converter frame by welding. Theyare to removed, if required, by grinding away theweld material holding the brackets to the frame.Caution is to be taken to prevent excessive damageto the parent material.

133. Replacement. Prior to replacement, allsurfaces to be welded are to be free of any rust orscale, they should be flat and flush fitting. All welds tothe top of the brackets are to be 10 mm fillets. Whenfitting these welds on brackets, a careful checkshould be made to ensure that they are correctlylocated and square with the frame. Tack weld thecastings in place and recheck the location beforefinal welding. Weld all round.

CAUTIONDo not weld across the mainmember flanges.

Welding

134. Refer to details in Group 16, para 148.

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SPECIFICATIONS

Equaliser centre bolt nut torque................................................................................................ 200Nm (150 lb ft)

Radius rod mounting bolt nut torque ......................................................................................... 100 Nm (75 lb ft)

Radius rod clamp bolt nut torque............................................................................................... 100 Nm (75 lb ft)

Equaliser suspension ‘U’ bolt nut torque.................................................................................. 415 Nm (310 lb ft)

Single point centre ‘U’ bolt nut torque...................................................................................... 680 Nm (501 lb ft)

Single point spring mounting end cap nut torque..................................................................... 380 Nm (280 lb ft)

Single point axle ‘U’ bolt nut torque ......................................................................................... 400 Nm (295 lb ft)

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ELECTRICAL - GROUP 15

Description

135. The electrical system is a basic 12 volt electricalsystem coupled to the towing vehicle and trailer by a 12pin NATO socket and plug. All lighting connected to theelectrical system is 12 volt.

136. An electrical wiring diagram is shown inFigure 42.

KEY TO PIN CONNECTIONS COLOUR CODE

A Not used Not used

B Stop light Red

C Not used Not used

D Earth White

E Tail light Brown

F Not used Not used

H Not used Not used

J Not used Not used

K Not used Not used

L Not used Not used

M Left turn indicator Yellow

N Right turn indicator Green

Figure 42Electrical circuit diagram.

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SPECIFICATIONS

System voltage ....................................................................................................................................... 12 V dc

Connector plug................................................................................................................................12 pin NATO

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VEHICLE H 796-1 ELECTRICAL AND MECHANICALIssue 1, May 00 ENGINEERING INSTRUCTIONSAmended Sep 04

42 AL 1

FRAME ASSEMBLY - GROUP 16

Description

137. The dolly converter is of prefabricated steelframe construction with two major components.These are:

a. Dolly frame.

b. Drawbar.

138. Dolly frame. The dolly frame is a single pieceall steel welded construction manufactured from 350grade steel for the frame members and 250 gradesteel for the decking area. The dolly frame carries thefifth wheel used for connection of a trailer to the dollyconverter, braking system and suspension units. Thesuspension units may be of the single point orequaliser type.

139. Drawbar. The drawbar frame is a single pieceall steel welded construction manufactured from 350grade steel for the frame members and 250 gradesteel for the decking area. The drawbar carries thebrake air system connection lines/dummy couplingsand electrical lines for connection to a prime moverand trailer. The supply lines are supported by aflexible mast (pogo stick) for security and ease ofconnection. A drop type support leg is attached to thedrawbar for support during parking without a primemover.

Drawbar Assembly

140. Removal.

a. Disconnect the brake air lines andelectrical harness form the drawbarassembly.

b. Extract the retaining pin from the drop legstorage bracket hinge pin, withdraw thepin from the bracket and swing down theleg.

c. Extract the retaining pin from theadjusting pin, withdraw the pin to releasethe lower drop leg and adjust the length ofthe leg to suit the level of the drawbar.Insert the adjusting pin into the nearestlocating hole in the upper and lower legand secure with the retaining pin. Refer toFigure 43.

NOTEDunnage may need to be placed belowthe drop leg foot to achieve the correctheight.

d. Place supports under the rear of thedrawbar, for support when the dolly frameand drawbar are separated.

Figure 43Drawbar pivot bushes.

e. Remove the hexagon nuts from the twopivot bolts. Remove the two bolts andpivot shafts.

WARNINGEnsure that the drawbar is securelyand safely supported and that thewheels on the dolly are chockedbefore removing the pivot pins.

f. Remove the four tapered rubber bushesand lift the drawbar clear of the dollyframe

NOTEIn the case of the dolly converter fittedwith the single point suspension unit,another two pins must be removedfrom the elongated holes at eachdrawbar pivot point.

141. Installation.

a. Position the drawbar pivot points into thedolly converter frame and securely supportin this position.

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b. Fit the four tapered bushes into the pivotholes.

c. Fit the pivot shaft and pivot bolts from theouter side of each pivot. Fit the large flatwasher with a new nyloc nut. Tighten tothe specified torque.

d. If working on the dolly converter fitted withthe single point suspension, insert thelocking pins into the elongated holes ateach drawbar pivot point and secure withthe retaining pins.

e. Refit the brake air lines and electricalharness to the drawbar assembly.

Fifth Wheel

142. Removal. Refer to Figure 44. Clean andremove the fifth wheel from the dolly frame asfollows:

a. Remove the two retaining bolts from thefifth wheel frame, to allow the extractionof the pivot pins.

Figure 44Fifth wheel layout.

b. Pull the two pivot pins from the fifth wheelframe and dolly brackets.

c. Lift the fifth wheel clear of the dolly frame.

143. Disassembly. Invert the fifth wheel with thelocks in the open position. Use the followingprocedure to remove parts. Refer to Figure 45.

a. Extract the cotter pin (21) and remove therelease handle (26).

b. Extract the cotter pin (25) and lock pin(24) and remove the secondary lock arm(22) and spring (23).

c. Extract the locking arrangement cotter pin(15) and lock pin (14) and remove thelockset (13) and ‘U’ spring (20).

d. Use a helper wedge to hold back thelocking plunger (11).

e. Remove the release lever nut (7) andscrew out the bolt (4). Extract the twowashers (8) and remove the release lever(6) and release handle (5).

f. Remove the helper wedge, locking plunger(11) and spring (10).

g. Remove the hex head jam nut (12) andthe stationary lock (13).

h. Remove the socket head capscrew (16),hug locknut (19), adjusting wedge (18)and spring (17).

i. Inspect the four rubber mountings, connectedto the underside of the fifth wheel frame,for damage or deterioration. If any faultsare evident, remove and discard themountings.

144. Reassembly.

a. Lubricate all moving parts before reassembly.

b. Install adjusting wedge (18), spring (17)and socket head capscrew (16), andtighten the screw until one threadprotrudes from the hug locknut (19). Finaladjustment will be made after the fifthwheel has been assembled.

c. Install spring (10) and plunger (11). Usethe helper wedge or any other method tohold the plunger (11) back, to assist in theinstallation of the release lever (6).

d. Install the release lever (6) in the castingand the release handle (5) onto therelease lever (6).

e. Fit a washer (8) between the releaselever (6) and the casting. Install therelease lever (6) into the slot in theplunger (11).

f. Install the other washer (8) on thecapscrew (4) and insert it through therelease arm (6), then screw the capscrewinto the casting (9).

g. Install the stationary lock (13) and jam nut(12), and tighten.

Releasehandle

Fifth wheelmounting bracket Pivot pin

Retainingbolt

Rubbermounting

Releasehandle

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Figure 45Fifth wheel assembly - exploded view.

6

24

7

15 14

13

1910

11

12

1617

1825

21

26 20

23

22

3

9

21

3

12

4

8

5

Item Description Qty Item Description Qty

1. Pivot pin 2 15. ¼” X 2 ½” Cotter pin 1

2. Bushing 2 16. Socket head cap screw 1

3. Grease nipple 2 17. Compression spring 1

4. Bolt 2 18. Adjusting wedge 1

5. Release handle 1 19. 5/8”-11 Locknut 1

6. Release lever 1 20. ‘U’ spring 1

7. Hexagon locknut 1 21. 1/8” x 1” Cotter pin 1

8. Plain washer 1 22. Secondary lock arm 1

9. Fifth wheel plate 1 23. Spring 1

10. Compression spring (red) 1 24. Lock pin 1

11. Locking plunger 2 25. ¼” x 2” Cotter pin 1

12. Jam nut 1 26. Release handle 1

13. Lockset for 3½” kingpin 1 27. Aeon rubber mounting (not 4

14. Lock pin 1 shown)

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ELECTRICAL AND MECHANICAL VEHICLE H 796-1ENGINEERING INSTRUCTIONS Issue 1, May 00

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h. Install the ‘U’ spring (20).

i. Lubricate the hinged lock pin hole withNever-Seez.

j. Insert the hinged lock (13), lock pin (14)and cotter pin (15). Splay the ends of thecotter pin to secure the assembly.

k. Install the release handle (26) into thecasting (9) and lubricate the secondarylock pin hole with Never-Seez.

l. Fit the secondary lock (22) to the releasehandle (26). Insert the cotter pin (21) intothe release handle and splay the ends.

m. Install the secondary lock pin (24) andcotter ping (25). Splay the ends of thecotter pin.

n. Lock the fifth wheel and install the spring(23).

o. Check the fifth wheel for correct lockingoperation. Carry out final adjustmentsusing a Holland TLN-1500, 3 ½ in. locktester or a new kingpin, with the fifth wheelin the locked position.

NOTEThe locking plunger (11) must movefreely behind the hinged lock (13) whenin the locked position. Tighten or loosenthe capscrew (16) to achieve correctlock clearance on the kingpin. Checkboth the locking and unlocking motion.

WARNINGOver-adjustment can cause a potentialpartial lock.

p. If the rubber mountings have been removed,due to damage or deterioration, replacethe mountings now. The mountings shouldbe compressed and under load in theunladen position, thus preventing clatter.At any given turntable height, themountings should be compressed 12 mm(½ inch).

145. Installation.

a. Apply grease to the pivot pins beforeinstalling the fifth wheel.

b. Place the fifth wheel on the dolly frame,line up the fifth wheel frame pin holes with

the dolly mounting bracket pin holes andinsert the pivot pins (1).

c. Refit the two retaining bolts to the fifthwheel frame, to prevent accidental releaseof the pivot pins.

Drawbar Eye

146. Inspection Standard. Measure the insidediameter of the drawbar bush insert and the thicknessof the drawbar tongue to determine whether theyhave worn beyond the allowable limits. Refer toSpecifications for wear limits. The bush insert mustbe replaced if the inside diameter is beyond the wearlimits. If the thickness of the drawbar eye tongue isless than the allowable limits the complete drawbareye must be replaced. Drawbar eyes that have beenbent, cracked, or deformed in any other way must beremoved and discarded. They are not to be reclaimedby welding or straightening.

147. Replacement of Drawbar Eye Bush InsertAnd Drawbar Eye. Replace the drawbar eye insertbush and drawbar eye using the followingprocedures:

a. Replacement of Drawbar Eye BushInsert. Replace the drawbar eye bush insertas follows:

(1) Park the dolly converter in a suitablearea of the workshop, apply theparking brakes, and chock thewheels to prevent movement.

(2) Place the drawbar assembly in ahorizontal position and support itusing the drawbar support stand.

(3) Place an appropriate support underthe neck of the drawbar eye so thatthe drawbar eye is placed firmly onthe support.

(4) Using either a power operated ormanual hack saw cut a vertical slit inthe bush insert.

CAUTIONDo not cut into the body of thedrawbar eye.

(5) Using a suitable mandrel and ahammer, drive the worn bush insertout of the drawbar eye and discard it.

(6) Apply a light coat of grease to theexternal surface of the new bushinsert and position the insert with theslot located at the rear and at 45degrees to the drawbar centre line.Drive the bush insert into the drawbar

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VEHICLE H 796-1 ELECTRICAL AND MECHANICALIssue 1, May 00 ENGINEERING INSTRUCTIONSAmended Sep 04

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eye using the mandrel and a hammeruntil it is flush with the lower surface.

(7) Clean any excess grease from thedrawbar eye and using an anglegrinder, or other suitable tool, removeexcess bush insert material so that itis flush with the drawbar eye on bothsides.

CAUTIONDo not remove any metal from thedrawbar eye.

(8) Apply a light coat of grease to theinside of the insert bush.

b. Replacement of Drawbar Eye. Replacethe drawbar eye as follows:

(1) Park the dolly converter in asuitable area of the workshop, applythe parking brakes, and chock thewheels to prevent movement.

(2) Place the drawbar assembly in ahorizontal position and support itusing the drawbar support stand.

(3) Remove the cotter pin, retaining nutand washer, and remove thedrawbar eye from the drawbar.Discard all removed parts.

NOTEUse a new washer, nut and cotter pinwhen fitting a new drawbar eye. Do notre-fit previously used parts.

(4) Apply a light coat of anti seizecompound to the cylindrical body ofthe drawbar eye, insert the drawbareye into the drawbar, assemble thewasher and retaining nut, and rotatethe drawbar eye so that the hole isvertical.

(5) Tighten the retaining nut to thespecified torque, to align the cotterpin hole tighten the nut further. Donot loosen the nut to align thecotter pin hole. Refer toSpecifications for torque settings.

Welding

148. Both the dolly frame and drawbar arefabricated from MS350 steel and of weldedconstruction, with the exception of the cast steelspring hangers and mounting brackets used on thesuspension assemblies. The following procedures arerecommended for welding work carried out on boththe frame and drawbar:

CAUTIONDisconnect the prime mover fromthe dolly converter, including theelectrical plug and air lines, beforeany welding is carried out.

CAUTIONWelding clamps must not beconnected to the wheel assemblies,otherwise damage to the wheelbearings may occur.

149. Frame members. All welding to the frame anddrawbar, apart from welding to the dolly converterspring hangers and mounting brackets, may becarried out with either a MIG welder or stickelectrodes using normal welding techniques.

150. Spring hangers/mounting brackets. Anywelding work carried out on the dolly converter springhangers or mounting brackets should be carried outwith a MIG welder, however, they may be weldedusing low hydrogen stick electrodes.

NOTELow Hydrogen Electrodes must beoven dried to a temperature of 370-430�C if they have been exposed to theatmosphere for more than 30 minutes,or if there is any doubt as to themoisture content. Only one re-baking ofthe electrodes is permissible.

151. Decking. The drawbar and dolly framedecking is made from MS250 steel plate. Thismaterial is readily weldable using conventionalwelding processes.

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ELECTRICAL AND MECHANICAL VEHICLE H 796-1ENGINEERING INSTRUCTIONS Issue 1, May 00

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SPECIFICATIONS

Drawbar pivot pin bolt torque ....................................................................................................... 200 Nm (150 lb ft)

Drawbar Eye:

Retaining nut torque........................................................................................................... 500 Nm (370 lb ft)

Maximum allowable end-float ..................................................................................................................... Nil

Maximum allowable side movement........................................................................................................... Nil

Maximum allowable internal diameter of bush insert ........................................................................ 51.5 mm

Minimum thickness of drawbar eye tongue....................................................................................... 42.5 mm

ENDDistribution List: VEH H 08.0 – Code 2 (Maint Level)

(Sponsor: MOB SPO, Mdm/Hvy B Veh)(Job No 200302231)

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