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WORKSHOP MANUAL FRONT LOADER LA1403 KiSC issued 08, 2008 A

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  • WORKSHOP MANUALFRONT LOADER

    LA1403

    KiSC issued 08, 2008 A

  • TO THE READER

    This Workshop Manual has been prepared to provide servicing personnel withinformation on the mechanism, service and maintenance of KUBOTA Front LoaderLA1403. It is divided into three parts, General, Mechanism and Servicing.

    GeneralInformation on the tractor identification, the general precautions, maintenance check

    list, check and maintenance and special tools are described.

    MechanismInformation on the construction and function are included. This part should be

    understood before proceeding with troubleshooting, disassembling and servicing.Refer to Front Loader Mechanism Workshop Manual (Code No. 9Y021-18210) for

    the one which has not been described in this workshop manual.

    ServicingInformation on the troubleshooting, servicing specification lists, tightening torque,

    checking and adjusting, disassembling and assembling, and servicing which coverprocedures, precautions, factory specifications and allowable limits.

    All information illustrations and specifications contained in this manual are based onthe latest product information available at the time of publication. The right is reservedto make changes in all information at any time without notice.

    July 2008 KUBOTA Corporation 2008

    KiSC issued 08, 2008 A

  • 1

    LA1403, WSM SAFETY INSTRUCTIONS

    SAFETY INSTRUCTIONS

    BEFORE SERVICING AND REPAIRING Read all instructions and safety instructions in this

    manual and on your engine safety decals. Clean the work area and engine. Park the machine on a firm and level ground. Allow the engine to cool before proceeding. Stop the engine, and remove the key. Disconnect the battery negative cable. Hang a DO NOT OPERATE tag in operator

    station.

    SAFETY FIRSTThis symbol, the industrys Safety Alert Symbol, is used throughout this manual and on labels on

    the machine itself to warn of the possibility of personal injury. Read these instructions carefully.It is essential that you read the instructions and safety regulations before you attempt to repair or use

    this unit.

    DANGER : Indicates an imminently hazardous situation which, if not avoided, will result indeath or serious injury.

    WARNING : Indicates a potentially hazardous situation which, if not avoided, could result indeath or serious injury.

    CAUTION : Indicates a potentially hazardous situation which, if not avoided, may result inminor or moderate injury.

    IMPORTANT : Indicates that equipment or property damage could result if instructions are notfollowed.

    NOTE : Gives helpful information.

    KiSC issued 08, 2008 A

  • 2

    LA1403, WSM SAFETY INSTRUCTIONS

    SAFETY STARTING Do not start the engine by shorting across starter

    terminals or bypassing the safety start switch. Unauthorized modifications to the engine may impair

    the function and / or safety and affect engine life.

    SAFETY WORKING Do not work on the machine while under the influence

    of alcohol, medication, or other substances or whilefatigued.

    Wear close fitting clothing and safety equipmentappropriate to the job.

    Use tools appropriate to the work. Makeshift tools,parts, and procedures are not recommended.

    When servicing is performed together by two or morepersons, take care to perform all work safely.

    Do not touch the rotating or hot parts while the engineis running.

    Never remove the radiator cap while the engine isrunning, or immediately after stopping. Otherwise, hotwater will spout out from radiator. Only removeradiator cap when cool enough to touch with barehands. Slowly loosen the cap to first stop to relievepressure before removing completely.

    Escaping fluid (fuel or hydraulic oil) under pressurecan penetrate the skin causing serious injury. Relievepressure before disconnecting hydraulic or fuel lines.Tighten all connections before applying pressure.

    Wear a suitable hearing protective device such asearmuffs or earplugs to protect against objectionableor uncomfortable loud noises.

    Do not open high-pressure fuel system.High-pressure fluid remaining in fuel lines can causeserious injury. Do not disconnect or attempt to repairfuel lines, sensors, or any other components betweenthe high-pressure fuel pump and injectors on engineswith high pressure common rail fuel system.

    High voltage exceeding 100 V is generated in theECU, and is applied to the injector.Pay sufficient caution to electric shock whenperforming work activities.

    KiSC issued 08, 2008 A

  • 3

    LA1403, WSM SAFETY INSTRUCTIONS

    AVOID FIRES Fuel is extremely flammable and explosive under

    certain conditions. Do not smoke or allow flames orsparks in your working area.

    To avoid sparks from an accidental short circuit,always disconnect the battery negative cable first andconnect it last.

    Battery gas can explode. Keep sparks and openflame away from the top of battery, especially whencharging the battery.

    Make sure that no fuel has been spilled on the engine.

    VENTILATE WORK AREA If the engine must be running to do some work, make

    sure the area is well ventilated. Never run the enginein a closed area. The exhaust gas contains poisonouscarbon monoxide.

    PREVENT ACID BURNS Sulfuric acid in battery electrolyte is poisonous. It is

    strong enough to burn skin, clothing and causeblindness if splashed into eyes. Keep electrolyteaway from eyes, hands and clothing. If you spillelectrolyte on yourself, flush with water, and getmedical attention immediately.

    DISPOSE OF FLUIDS PROPERLY Do not pour fluids into the ground, down a drain, or

    into a stream, pond, or lake. Observe relevantenvironmental protection regulations when disposingof oil, fuel, coolant, electrolyte and other harmfulwaste.

    KiSC issued 08, 2008 A

  • 4

    LA1403, WSM SAFETY INSTRUCTIONS

    PREPARE FOR EMERGENCIES Keep a first aid kit and fire extinguisher handy at all

    times. Keep emergency numbers for doctors, ambulance

    service, hospital and fire department near yourtelephone.

    KiSC issued 08, 2008 A

  • 5

    LA1403, WSM SAFETY INSTRUCTIONS

    The following safety decals are installed on the machine.If a decal becomes damaged, illegible or is not on the machine, replace it. The decal part number is listed inthe parts list.

    SAFETY DECALS

    KiSC issued 08, 2008 A

  • 6

    LA1403, WSM SAFETY INSTRUCTIONS

    KiSC issued 08, 2008 A

  • 7

    LA1403, WSM SAFETY INSTRUCTIONS

    KiSC issued 08, 2008 A

  • 8

    LA1403, WSM LOADER TERMINOLOGY

    LOADER TERMINOLOGY

    (1) Mounting Pin(2) Side Frame(3) Control Valve

    (4) Boom Cylinder(5) Main Frame

    (6) Boom(7) Bucket Cylinder

    (8) Bucket(9) Control Lever

    KiSC issued 08, 2008 A

  • 9

    LA1403, WSM SPECIFICATIONS

    SPECIFICATIONS Suitable Tractor

    LA1403 : M96S, M108S

    [1] LOADER SPECIFICATIONS

    W1027852

    [2] BUCKET SPECIFICATIONS

    W1013973

    Loader Model LA1403

    Tractor Model M96S M108S

    Wheel Base (WB) 2435 mm (95.9 in.)

    Front Tires 12.4-24 13.6-24

    Rear Tires 18.4-30 18.4-34

    Boom CylinderBore 70 mm (2.76 in.)

    Stroke 606 mm (23.9 in.)

    Bucket CylinderBore 70 mm (2.76 in.)

    Stroke 516.5 mm (20.3 in.)

    Control Valve One Detent Float Position, Power Beyond Circuit

    Rated Flow 65 L/min.(17.2 U.S.gals/min., 14.3 Imp.gals/min.)

    Maximum Pressure 20.7 MPa (211 kgf/cm2, 3002 psi)

    Net Weight (Approximate) 850 kg (1874 lbs)

    Loader Model LA1403

    ModelROUND 72 in. ROUND 84 in.

    LIGHT MATERIAL

    84 in.ROUND 96 in.

    LIGHT MATERIAL 96

    in.

    Type Quick Attach

    Width 1830 mm (72.0 in.) 2135 mm (84.0 in.) 2440 mm (96.0 in.)

    Depth (L) 650 mm (25.59 in.) 750 mm (29.53 in.)665 mm (26.2 in.)

    800 mm (31.5 in.)

    Height (M) 665 mm (26.18 in.) 715 mm (28.15 in.)750 mm (29.5 in.)

    764 mm (30.1 in.)

    Length (N) 900 mm (35.43 in.) 1000 mm (39.37 in.)770 mm (30.3 in.)

    910 mm (35.8 in.)

    Capacity

    Struck 0.44 m3 (15.5 cu.ft.)

    0.52 m3 (18.4 cu.ft.)

    0.63 m3 (22.3 cu.ft.)

    0.66 m3 (23.3 cu.ft.)

    0.80 m3 (28.3 cu.ft.)

    Heaped 0.55 m3 (19.4 cu.ft.)

    0.64 m3 (22.6 cu.ft.)

    0.79 m3 (27.9 cu.ft.)

    0.75 m3 (26.5 cu.ft.)

    0.98 m3 (34.6 cu.ft.)

    Weight 210 kg (463 lbs) 235 kg (518 lbs) 255 kg (562 lbs) 275 kg (606 lbs) 316 kg (697 lbs)

    KiSC issued 08, 2008 A

  • 10

    LA1403, WSM SPECIFICATIONS

    [3] DIMENSIONAL AND OPERATIONAL SPECIFICATIONS

    Dimensional Specifications

    W1013874

    Operational Specifications

    W1030299

    Loader Model LA1403

    Tractor Model M96S, M108S

    Boom Cylinder Fulcrum Point HEIGHT POWER

    (A) Maximum lift height to pivot pin 3700 mm(145.7 in.)

    3370 mm(132.7 in.)

    (B) Maximum lift height under level bucket 3470 mm(136.6 in.)

    3160 mm(124.4 in.)

    (C) Clearance with bucket dumped 2860 mm(112.6 in.)

    2490 mm(98.0 in.)

    (D) Reach at maximum lift height(Dumping Reach)

    590 mm(23.2 in.)

    975 mm(38.4 in.)

    (E) Maximum dump angle 0.91 rad (52 ) 1.1 rad (63 )

    (F) Reach with bucket on ground 2230 mm (87.8 in.)

    (G) Bucket roll-back angle 0.70 rad (40 )

    (H) Digging depth 60 mm (2.4 in.) 65 mm (2.6 in.)

    (J) Overall height in carry position 1700 mm (66.9 in.)

    (a) Length 800 mm (31.5 in.)

    Loader Model LA1403

    Tractor Model M96S, M108S

    Boom Cylinder Fulcrum Point HEIGHT POWER

    Lift capacity (Bucket bottom mid point) 1350 kg (2976 lbs) 1400 kg (3086 lbs)

    (U) Lift capacity (Bucket pivot pin, max. height) 1895 kg (4178 lbs) 1950 kg (4299 lbs)

    (V) Lift capacity (800 mm forward, max. height) 1210 kg (2668 lbs) 1350 kg (2976 lbs)

    (W) Lift capacity (Bucket pivot pin, 1500 mm height) 2125 kg (4685 lbs) 2380 kg (5247 lbs)

    (X) Lift capacity (800 mm forward, 1500 mm height) 1575 kg (3472 lbs) 1840 kg (4057 lbs)

    (Y) Breakout force (Bucket pivot pin) 24860 N (5589 lbf) 29250 N (6576 lbf)

    (Z) Breakout force (800 mm forward) 17190 N (3864 lbf) 22200 N (4991 lbf)

    (VV) Bucket roll-back force at maxumum height 13720 N (3084 lbf) 16080 N (3615 lbf)

    (XX) Bucket roll-back force at 1.5 m (59 in.) 25860 N (5814 lbf)

    (ZZ) Bucket roll-back force at ground level 25810 N (5802 lbf)

    Raising time 4.7 sec.

    Lowering time 3.7 sec.

    Bucket dumping time 2.8 sec.

    Bucket roll-back time 2.9 sec.

    KiSC issued 08, 2008 A

  • CONTENTS

    GENERAL

    1. LOADER IDENTIFICATION............................................................................ G-12. GENERAL PRECAUTIONS ............................................................................ G-23. LUBRICANTS .................................................................................................. G-34. TIGHTENING TORQUES ............................................................................... G-4

    [1] GENERAL USE SCREWS, BOLTS AND NUTS (FOR FRONTLOADER AND BACKHOE) ...................................................................... G-4

    [2] STUD BOLTS............................................................................................ G-4[3] AMERICAN STANDARD SCREWS, BOLTS AND NUTS WITH UNC

    OR UNF THREADS ................................................................................. G-5[4] PLUGS....................................................................................................... G-5[5] HYDRAULIC FITTINGS............................................................................ G-6

    5. MAINTENANCE CHECK LIST....................................................................... G-76. CHECK AND MAINTENANCE....................................................................... G-8

    [1] CHECK POINTS OF EACH USE OR DAILY ....................................... G-8[2] CHECK POINTS OF EVERY 10 HOURS .............................................. G-9[3] CHECK POINT OF EVERY 50 HOURS ............................................... G-9

    KiSC issued 08, 2008 A

  • G-1

    LA1403, WSM G GENERAL

    1. LOADER IDENTIFICATIONWhen contacting your local KUBOTA distributor, always specify

    front loaders serial number (1).

    W1010477

    (1) Serial Number

    KiSC issued 08, 2008 A

  • G-2

    LA1403, WSM G GENERAL

    2. GENERAL PRECAUTIONS During disassembly, carefully arrange removed parts in a clean

    area to prevent later confusion. Screws, bolts and nuts should bereplaced in their original positions to prevent reassembly errors.

    When special tools are required, use genuine KUBOTA tools.Special tools which are not used frequently should be madeaccording to the drawings provided.

    Clean parts before measuring them. Use only genuine KUBOTA parts for parts replacement to

    maintain backhoe performance and to assure safety. O-rings and oil seals must be replaced during reassembly. Apply

    grease to new O-rings or oil seals before reassembling. Nipples must be tightened to the specified torque. Excessive

    torque may cause damages hydraulic units or nipples, andinsufficient torque will result in oil leaks.

    When using a new hose or pipe, tighten nuts to the specifiedtorque once, then loosen them (approx. by 45 ) to allow hose orpipe to settle before retightening to the specified torque (exceptsealtaped parts).

    When removing both ends of a pipe, remove the lower end first. Use two pliers in removal and reinstallation; one to hold the static

    side, and the other to turn the side being removed to avoidtwisting.

    Check to see that sleeves of flareless connectors and taperedsections of hoses are free of dust and scratches.

    After tightening nipples, clean the joint and apply the maximumworking pressure 2 to 3 times to check for oil leak.

    W1010572

    A : Grease

    KiSC issued 08, 2008 A

  • G-3

    LA1403, WSM G GENERAL

    3. LUBRICANTSTo prevent serious damage to hydraulic systems, use only specified fluid or its equivalent.

    * KUBOTA original transmission hydraulic fluid** Extreme pressure and containing Molybdenum disulfide is recommended. This grease may specify Moly Ep

    on its label.

    PlaceCapacity

    Lubricants, type of greaseM96S, M108S

    Transmission case60.0 L

    15.9 U.S.gals13.2 Imp.gals

    KUBOTA UDT or SUPER UDT fluid*

    Grease nipples Until grease overflows. Moly Ep type grease**

    KiSC issued 08, 2008 A

  • G-4

    LA1403, WSM G GENERAL

    4. TIGHTENING TORQUES[1] GENERAL USE SCREWS, BOLTS AND NUTS (FOR FRONT LOADER

    AND BACKHOE)Screws, bolts, and nuts whose tightening torques are not specified in this Workshop Manual should be

    tightened according to the table below.

    W1034542

    [2] STUD BOLTS

    W1048139

    Indication on top of bolt No-grade or 4T 7T or Property class 8.8

    9T orProperty class 10.9

    Material of opponent part Ordinariness Aluminum Ordinariness Aluminum Ordinariness

    Unit Diameter Nm kgfm lbfft Nm kgfm lbfft Nm kgfm lbfft Nm kgfm lbfft Nm kgfm lbfft

    M6(6 mm, 0.24 in.)

    7.9to9.3

    0.80to

    0.95

    5.8to

    6.8

    7.9to

    8.8

    0.80to

    0.90

    5.8to

    6.5

    9.81to

    11.2

    1.00to

    1.15

    7.24to

    8.31

    7.9to

    8.8

    0.80to

    0.90

    5.8to

    6.5

    12.3to

    14.2

    1.25to

    1.45

    9.05to

    10.4

    M8(8 mm, 0.31 in.)

    18to20

    1.8to

    2.1

    13to15

    17to19

    1.7to

    2.0

    13to14

    24to27

    2.4to

    2.8

    18to20

    18to20

    1.8to

    2.1

    13to15

    30to34

    3.0to

    3.5

    22to25

    M10(10 mm, 0.39 in.)

    40to45

    4.0to

    4.6

    29to33

    32to34

    3.2to

    3.5

    24to25

    48to55

    4.9to

    5.7

    36to41

    40to44

    4.0to

    4.5

    29to32

    61to70

    6.2to

    7.2

    45to52

    M12(12 mm, 0.47 in.)

    63to72

    6.4to

    7.4

    47to53

    78to90

    7.9to

    9.2

    58to66

    63to72

    6.4to

    7.4

    47to53

    103to

    117

    10.5to

    12.0

    76.0to

    86.7

    M14(14 mm, 0.55 in.)

    108to

    125

    11.0to

    12.8

    79.6to

    92.5

    124to

    147

    12.6to

    15.0

    91.2to

    108

    167to

    196

    17.0to

    20.0

    123to

    144

    M16(16 mm, 0.63 in.)

    167to

    191

    17.0to

    19.5

    123to

    141

    197to

    225

    20.0to

    23.0

    145to

    166

    260to

    304

    26.5to

    31.0

    192to

    224

    M18(18 mm, 0.71 in.)

    246to

    284

    25.0to

    29.0

    181to

    209

    275to

    318

    28.0to

    32.5

    203to

    235

    344to

    402

    35.0to

    41.0

    254to

    296

    M20(20 mm, 0.79 in.)

    334to

    392

    34.0to

    40.0

    246to

    289

    368to

    431

    37.5to

    44.0

    272to

    318

    491to

    568

    50.0to

    58.0

    362to

    419

    Material of opponent part Ordinariness Aluminum

    Unit Diameter Nm kgfm lbfft Nm kgfm lbfft

    M8(8 mm, 0.31 in.)

    12to15

    1.2to

    1.6

    8.7to11

    8.9to11

    0.9to

    1.2

    6.5to

    8.6

    M10(10 mm, 0.39 in.)

    25to31

    2.5to

    3.2

    18to23

    20to25

    2.0to

    2.6

    15to18

    M12(12 mm, 0.47 in.)

    29.5to

    49.0

    3.0to

    5.0

    21.7to

    36.131.4 3.2 23.1

    M14(14 mm, 0.55 in.)

    62to73

    6.3to

    7.5

    46to54

    M16(16 mm, 0.63 in.)

    98.1to

    112

    10.0to

    11.5

    72.4to

    83.1

    M18(18 mm, 0.71 in.)

    172to

    201

    17.5to

    20.5

    127to

    148

    KiSC issued 08, 2008 A

  • G-5

    LA1403, WSM G GENERAL

    [3] AMERICAN STANDARD SCREWS, BOLTS AND NUTS WITH UNC ORUNF THREADS

    W1022485

    [4] PLUGS

    0000001666E

    GradeSAE GR.5 SAE GR.8

    Unit Nominal Diameter

    Nm kgfm lbfft Nm kgfm lbfft

    1/4 11.7 to 15.7 1.19 to 1.61 8.61 to 11.6 16.3 to 19.7 1.66 to 2.01 12.0 to 14.6

    5/16 23.1 to 27.7 2.35 to 2.83 17.0 to 20.5 33 to 39 3.4 to 4.0 24 to 29

    3/ 8 48 to 56 4.9 to 5.8 35.0 to 42.0 61 to 73 6.3 to 7.4 45 to 54

    1/ 2 110 to 130 11 to 13 80 to 96 150 to 178 15.2 to 18.2 110 to 132

    9/16 150 to 178 15.2 to 18.2 110 to 132 217 to 260 22.2 to 26.5 160 to 192

    5/ 8 204 to 244 20.8 to 24.8 150 to 180 299 to 357 30.5 to 36.4 220 to 264

    Shape Size

    Material of opponent part

    Ordinariness Aluminum

    Nm kgfm lbfft Nm kgfm lbfft

    Taperedscrew

    R1/8 13 to 21 1.3 to 2.2 9.4 to 15 13 to 21 1.3 to 2.0 9.4 to 15

    R1/4 25 to 44 2.5 to 4.5 18 to 32 25 to 34 2.5 to 3.5 18 to 25

    R3/8 49 to 88 5.0 to 9.0 37 to 65 49 to 58 5.0 to 6.0 37 to 43

    R1/2 58.9 to 107 6.00 to 11.0 43.4 to 79.5 59 to 78 6.0 to 8.0 44 to 57

    Straightscrew

    G1/4 25 to 34 2.5 to 3.5 18 to 25

    G3/8 62 to 82 6.3 to 8.4 46 to 60

    G1/2 49 to 88 5.0 to 9.0 37 to 65

    KiSC issued 08, 2008 A

  • G-6

    LA1403, WSM G GENERAL

    [5] HYDRAULIC FITTINGS Adaptors, Elbows and Others

    NOTE When connecting a hose with flare nut, after tightening the nut with specified torque, return it

    approximately 45 degrees (0.79 rad) and re-tighten it to specified torque.W1015484

    Item Shape Thread sizeTightening torque

    Nm kgfm lbfft

    Adjustable elbow, Adaptor (O-ring port) (UNF)

    [A] Nut Type[B] No Nut Typea : O-ring

    9/16 37 to 44 3.8 to 4.5 27 to 33

    3/4 48 to 54 4.9 to 5.5 35 to 40

    7/8 77 to 85 7.9 to 8.6 57 to 62

    Hose fitting, Flare nut (UNF)

    9/16 22 to 25 2.3 to 2.6 16 to 19

    3/4 36 to 40 3.6 to 4.1 26 to 30

    7/8 43 to 50 4.4 to 5.0 32 to 36

    Adaptor (NPT)

    1/4 30 to 50 3.1 to 5.0 23 to 36

    3/8 39 to 60 4.0 to 6.1 29 to 44

    1/2 49 to 58 5.0 to 5.9 36 to 43

    KiSC issued 08, 2008 A

  • G-7

    LA1403, WSM G GENERAL

    5. MAINTENANCE CHECK LISTTo keep the machine working in good condition as well as to avoid any accident and trouble, carry out periodic

    inspection and maintenance. Check the following points before use.

    W1013874

    Service Interval Check Points Reference pageDaily (Each use) Check the transmission fluid level G-8

    Check the hydraulic hoses G-8Every 10 hours Grease all grease nipples G-9

    Lubricate joints of control level linkage G-9Every 50 hours Check the main frame mounting bolts G-9

    KiSC issued 08, 2008 A

  • G-8

    LA1403, WSM G GENERAL

    6. CHECK AND MAINTENANCECAUTION

    When checking and repairing, park the tractor on flat ground and apply the parking brake. When checking and repairing, lower the bucket and stop the engine.

    [1] CHECK POINTS OF EACH USE OR DAILYChecking Transmission Fluid Level1. Check the oil level at the gauge (1).2. If the level is too low, add new oil to the prescribed level.

    IMPORTANT Use only KUBOTA UDT or SUPER UDT fluid.

    Use of other oil may damage the transmission or hydraulicsystem. Refer to 3. LUBRICANTS.

    W1010960

    Checking Hydraulic Hoses1. With the engine off and bucket on the ground, check all hydraulic

    hoses (1) for cuts or wear.2. Check for signs of leaks and make sure all fittings are tight.3. If defects are found, replace them.

    W1011064

    (1) Gauge(2) Oil Filling Plug

    (A) Oil level is acceptable within this range.

    (1) Hydraulic Hose(2) Cardboard

    (3) Magnifying Glass

    KiSC issued 08, 2008 A

  • G-9

    LA1403, WSM G GENERAL

    [2] CHECK POINTS OF EVERY 10 HOURSGreasing1. Inject grease in all grease fitting with a hand grease gun.

    W1011132

    Lubricating1. Lubricate joints of control lever linkage.

    W1011274

    [3] CHECK POINT OF EVERY 50 HOURSChecking Main Frame Mounting Bolts

    CAUTION Never operate front loader with a loose main frame. Any time bolts are loosened, retighten to specified torque. Check all bolts frequently and keep them tight.

    1. Check the main frame bolts and nuts regularly especially whennew. If they are loose, tighten them as follows.

    W1013969

    Tightening torque

    Main frame mounting bolt (M20)

    368 Nm37.5 kgfm271 lbfft

    Main frame mounting bolt (M18)

    319 Nm32.5 kgfm235 lbfft

    Main frame mounting nut (M18)

    343 Nm35.0 kgfm253 lbfft

    (1) Main frame(2) Bolt (M18)(3) Nut (M18)

    (4) Bolt (M20)(5) Bolt (M20)(6) Spacer

    KiSC issued 08, 2008 A

  • CONTENTS

    MECHANISM

    1. CONTROL VALVE ASSEMBLY (STANDARD VALVE) ............................... M-1[1] HYDRAULIC CIRCUIT.............................................................................. M-1[2] STRUCTURE............................................................................................. M-2[3] OPERATION.............................................................................................. M-3[4] RELIEF VALVE......................................................................................... M-9

    2. CONTROL VALVE ASSEMBLY (SELF-LEVELING VALVE) ..................... M-12[1] HYDRAULIC CIRCUIT............................................................................ M-12[2] STRUCTURE........................................................................................... M-13[3] OPERATION............................................................................................ M-14[4] RELIEF VALVE....................................................................................... M-54

    (1) Main Relief Valve ............................................................................... M-54(2) Overload Relief Valve ........................................................................ M-55

    3. BOOM CYLINDER AND BUCKET CYLINDER.......................................... M-574. 3RD FUNCTION VALVE (OPTION)............................................................ M-58

    [1] HYDRAULIC CIRCUIT............................................................................ M-58[2] 3RD FUNCTION SOLENOID VALVE OPERATION ............................ M-59[3] ELECTRICAL CIRCUIT .......................................................................... M-62

    5. HYDRAULIC ACCUMULATOR (OPTION)................................................... M-63[1] HYDRAULIC CIRCUIT............................................................................ M-63[2] ACCUMULATOR VALVE........................................................................ M-64[3] HYDRAULIC ACCUMULATOR............................................................... M-65[4] ACCUMULATOR RELIEF VALVE ......................................................... M-66

    KiSC issued 08, 2008 A

  • M-1

    LA1403, WSM FRONT LOADER

    1. CONTROL VALVE ASSEMBLY (STANDARD VALVE)[1] HYDRAULIC CIRCUIT

    To operate the front loader, the hydraulic oil pressurized by the hydraulic pump flows from P port through the boomcontrol valve (5) and the bucket control valve (6) to P.B. port or T port.

    (1) Boom Cylinder(2) Bucket Cylinder(3) Control Valve Assembly(4) Relief Valve

    (5) Boom Control Valve(6) Bucket Control Valve(7) Orifice

    P : From PumpT : To TankP.B.: To 3-Point Hydraulic

    System

    A1 : A1 Port A2 : A2 Port B1 : B1 Port B2 : B2 Port

    KiSC issued 08, 2008 A

  • M-2

    LA1403, WSM FRONT LOADER

    [2] STRUCTURE

    The control valve assembly is composed of one casting block and four major sections as shown above.(1) Inlet and Outlet Section

    There are P and T port in this section.The P port is connected to the OUTLET port of hydraulic block by the hydraulic hose.The T port is connected to the TANK port of hydraulic block by the hydraulic hose.

    (2) Boom Control SectionThe boom control valve consists of 4-position, 6-connection, detent, spring center type spool, a mono block valve

    housing, load check valve, etc. This valve connects to A1 and B1 port and controls oil flow to the boom cylinder.(3) Bucket Control Section

    The bucket control valve consists of 3-position, 6-connection, no detent spring center type spool, a mono blockvalve housing, load check valve, etc. This valve connects to A2 and B2 port and controls oil flow to the bucket cylinder.(4) Power Beyond

    This section includes P.B. port which is connected to the INLET port of hydraulic block by the hydraulic hose, andfeeds oil to the 3-Point hydraulic control valve.

    (1) Inlet Section(2) Boom Control Valve(3) Bucket Control Valve(4) Outlet Section

    P : P PortT : T Port

    A1 : A1 PortA2 : A2 Port

    B1 : B1 PortB2 : B2 PortP.B. :P.B. Port

    KiSC issued 08, 2008 A

  • M-3

    LA1403, WSM FRONT LOADER

    [3] OPERATION Control Lever at NEUTRAL Position

    1. Pressure-fed oil from the hydraulic pump is delivered into P port in the inlet section (2).2. As the load check valve (9), (10) are closed in the neutral position, oil flows along the notched section of the spools

    (4), (8) to the P.B. port through the P.B. passage 1 (3) and 2 (7).3. Then the oil is fed to the 3-Point hydraulic system from the P.B. port.

    (1) Boom Control Valve(2) Inlet Section(3) P.B. Passage 1(4) Spool(5) Bucket Control Valve

    (6) Outlet Section(7) P.B. Passage 2(8) Spool(9) Load Check Valve

    (10) Load Check Valve

    P : P PortT : T Port

    A1 : A1 PortA2 : A2 Port

    B1 : B1 PortB2 : B2 PortP.B. :P.B. Port(a) Low Pressure

    KiSC issued 08, 2008 A

  • M-4

    LA1403, WSM FRONT LOADER

    Control Lever at UP Position1. When the hydraulic control lever is set to the UP

    position, the spool (5) of the boom control valve (3)moves to the right, which forms oil passages betweenpassage 1 (9) and B1 port, also between A1 port andP.B. passage 1 (7).

    2. As the oil passage from the neutral passage 1 (6) tothe P.B. passage 1 (7) is closed by the spool (5), thepressure-fed oil from the P port opens the load checkvalve (10) and flows through the notched section ofthe spool (5) and B1 port to extend the boom cylinder(1).

    3. Return oil from the boom cylinder flows from the A1port through the passage in the spool (5) and P.B.passage 1 (7) to bucket control valve (2).

    W1025879

    (1) Boom Cylinder(2) Bucket Control Valve(3) Boom Control Valve(4) Inlet section(5) Spool(6) Neutral Passage 1(7) PB Passage 1(8) Outlet Section(9) Passage 1

    (10) Load Check Valve

    P : P PortT : T Port

    A1 : A1 Port (From Boom Cylinder)

    B1 : B1 Port (To Boom Cylinder)

    P.B.:P.B. Port(a) Low Pressure(b) High Pressure

    KiSC issued 08, 2008 A

  • M-5

    LA1403, WSM FRONT LOADER

    Control Lever at DOWN Position1. When the hydraulic control lever is set to the

    DOWN position, the spool (5) moves to the left,which forms oil passages between passage 1 (9) andA1 port, also between B1 port and P.B. passage 1(7).

    2. As the oil passage from the neutral passage 1 (6) tothe P.B. passage 1 (7) is closed by the spool (5), thepressure-fed oil from the P port opens the load checkvalve (10) and flows through the notched section ofthe spool (5) and A1 port to retract the boom cylinder(1).

    3. Return oil from the boom cylinder flows from the B1port through the passage in the spool (5) and P.B.passage 1 (7) to the bucket control valve (2).

    W1026333

    (1) Boom Cylinder(2) Bucket Control Valve(3) Boom Control Valve(4) Inlet section(5) Spool(6) Neutral Passage 1(7) P.B. Passage 1(8) Outlet Section(9) Passage 1

    (10) Load Check Valve

    P : P PortT : T Port

    A1 : A1 Port (To Boom Cylinder)

    B1 : B1 Port (From Boom Cylinder)

    P.B.: P.B. Port(a) Low Pressure(b) High Pressure

    KiSC issued 08, 2008 A

  • M-6

    LA1403, WSM FRONT LOADER

    Control Lever at FLOAT Position1. When the hydraulic control lever is set to the

    FLOAT position, the spool (5) moves further to theleft from the DOWN position and is retained by thedetent mechanism (10).

    2. This forms oil passages among the A1 port, B1 portand T port. As a result, oil in the boom cylinder flowsfreely from the A1 port and B1 port through the T portto the transmission case.

    3. Oil entering the P port flows to the bucket controlvalve (2) through the neutral passage 1 (9) and P.B.passage 1 (8).Then the oil flows to the 3-Point hydraulic system.

    W1026767

    (1) Boom Cylinder(2) Bucket Control Valve(3) Boom Control Valve(4) Inlet section(5) Spool(6) Outlet Section(7) P.B. Passage 2(8) P.B. Passage 1(9) Neutral Passage 1

    (10) Detent Mechanism

    P : P PortT : T Port

    A1 : A1 PortB1 : B1 PortP.B.: P.B. Port(a) Low Pressure

    KiSC issued 08, 2008 A

  • M-7

    LA1403, WSM FRONT LOADER

    Control Lever at ROLL-BACK Position1. When the hydraulic control lever is set to the ROLL-

    BACK position, the spool (6) of the bucket controlvalve (2) moves to the left, which forms oil passagesbetween passage 2 (10) and B2 port, also betweenA2 port and T port.

    2. The oil passage from the P.B. passage 1 (5) to theP.B. passage 2 (7) is closed by the spool (6).Therefore, the pressure-fed oil from the P port flowsthrough the boom control valve (3), opens the loadcheck valve (9), and flows through the notchedsection of the spool (6) and B2 port to retract thebucket cylinder (1).

    3. Return oil from the bucket cylinder flows to thetransmission case through the A2 port and T port.

    W1027189

    (1) Bucket Cylinder(2) Bucket Control Valve(3) Boom Control Valve(4) Inlet section(5) P.B. Passage 1(6) Spool(7) P.B. Passage 2(8) Outlet Section(9) Load Check Valve

    (10) Passage 2

    P : P PortT : T Port

    A2 : A2 Port (From Bucket Cylinder)

    B2 : B2 Port (To Bucket Cylinder)

    P.B.: P.B. Port(a) Low Pressure(b) High Pressure

    KiSC issued 08, 2008 A

  • M-8

    LA1403, WSM FRONT LOADER

    Control Lever at DUMP Position1. When the hydraulic control lever is set to the DUMP

    position, the spool (6) of the bucket control valve (2)moves to the right, which forms oil passages amongpassage 2 (7), A2 port and B2 port.

    2. The oil passage from the P.B. passage 1 (5) to theP.B. passage 2 (7) is closed by the spool (6).Therefore, the pressure-fed oil from the P port flowsthrough the boom control valve (3), opens the loadcheck valve (9), and flows through the notchedsection of the spool (6) and A2 port to extend thebucket cylinder (1).

    3. Return oil from the bucket cylinder flows from the B2port to the passage 2 (10), and flows to the A2 porttogether with the pressure-fed oil from the P port.As a result, the dump speed is increased.

    (Reference) The oil pressure of the A2 port and B2 port is

    identical, but the bucket cylinder extends by thedifference of received pressure area (cylinder rodpart).

    W1027604

    (1) Bucket Cylinder(2) Bucket Control Valve(3) Boom Control Valve(4) Inlet section(5) P.B. Passage 1(6) Spool(7) P.B. Passage 2(8) Outlet Section(9) Load Check Valve

    (10) Passage 2

    P : P PortT : T Port

    A2 : A2 Port (To Bucket Cylinder)

    B2 : B2 Port (From Bucket Cylinder)

    P.B.: P.B. Port(b) High Pressure

    KiSC issued 08, 2008 A

  • M-9

    LA1403, WSM FRONT LOADER

    [4] RELIEF VALVEThe relief valve is adopted in the loader control valve.

    This relief valve is pilot operated type, it is suitable for ahigh pressure and large volumetric flow with betterpressure override performance than direct acting reliefvalves.

    This relief valve is a combination valve combining arelief operation and anti-cavitation operation.

    W1020742

    (1) Inlet Section of Control Valve(2) Main Relief Valve(3) Piston Poppet(4) Relief Valve Poppet(5) Housing(6) Check Valve Poppet(7) Pilot Section

    (8) Jam Nut(9) Acorn Nut

    (10) Piston Spring(11) Pilot Poppet(12) Pilot Spring(13) Adjust Screw

    KiSC issued 08, 2008 A

  • M-10

    LA1403, WSM FRONT LOADER

    Relief Operation[Step 1]

    The relief valve is in communication between the highpressure port HP and low pressure chamber LP. Oil isadmitted through the hole in piston poppet (4) andbecause of the differential area between diameter A andB relief valve poppet (1) and check valve poppet (2) aretightly seated as shown in the figure.

    W1028047

    [Step 2]The oil pressure in the high pressure port HP has

    reached the setting of the pilot spring force and unseatsthe pilot poppet (3). Oil flows around the poppet-throughthe cross drilled holes and to the low pressure chamberLP.

    W1028183

    [Step 3]The loss of oil behind the piston poppet (4), effected

    by the opening of pilot poppet (3), causes piston poppet(4) to move back and seat against pilot poppet (3). Thisshuts off the oil flow to the area behind relief valve poppet(1), and causes a low pressure area internally.

    W1028284

    [Step 4]The imbalance of pressure inside as compared to that

    of the high pressure port HP, forces the relief valvepoppet (1) to open and relief the oil directly to the lowpressure chamber LP in the valve. (Reference) Relief valve setting pressure :

    Condition Engine speed : Approx. 2600 min-1 (rpm) Oil temperature : 44 to 48 C

    110 to 120 F

    W1028383

    (1) Relief Valve Poppet(2) Check Valve Poppet

    (3) Pilot Poppet(4) Piston Poppet

    (3) Pilot Poppet

    (1) Relief Valve Poppet(3) Pilot Poppet

    (4) Piston Poppet

    Relief valve setting pressure

    Factory spec.

    20.3 to 21.0 MPa207 to 214 kgf/cm22950 to 3045 psi

    (1) Relief Valve Poppet

    KiSC issued 08, 2008 A

  • M-11

    LA1403, WSM FRONT LOADER

    Anti-cavitation OperationThe anti-void unit supplies oil to the high pressure

    port HP when cavitation has occurred. A lower pressureexists in the port HP compared to the low pressurechamber LP. The difference between the effective areaof diameter A and C causes imbalance of the checkvalve poppet (1) unseats, thus allowing oil from the lowpressure chamber LP to enter the port HP and fill thevoid.

    W1028551

    (1) Check Valve Poppet LP : Low Pressure HP : Hight Pressure

    KiSC issued 08, 2008 A

  • M-12

    LA1403, WSM FRONT LOADER

    2. CONTROL VALVE ASSEMBLY (SELF-LEVELINGVALVE)

    [1] HYDRAULIC CIRCUIT

    To operate the front loader, the hydraulic oil pressurized by the hydraulic pump flows from P port through thecontrol valve assembly (3) to P.B. port or T port. The oil flow in control valve assembly (3) functions as to maintain aHORIZONTAL position of bucket.

    (1) Boom Cylinder(2) Bucket Cylinder(3) Control Valve Assembly

    (4) Relief Valve(5) Boom Control Valve(6) Bucket Control Valve

    P : From PumpT : To TankP.B.: To 3-Point Hydraulic

    System

    A1 :A1 Port A2 :A2 Port B1 :B1 Port B2 :B2 Port

    KiSC issued 08, 2008 A

  • M-13

    LA1403, WSM FRONT LOADER

    [2] STRUCTURE

    The control valve assembly is composed of three major sections.(1) Boom Control Valve

    The boom control valve consists of 4-position, 8-connection, detent, spring center type spool, a valve housing, loadcheck valve, etc.. This valve connects to A1 and B1 port and controls oil flow to the boom cylinder.(2) Self-leveling Valve

    The self-leveling control valve consists of 2-position, 6-connection, detent type spool, a valve housing, etc.. Theself-leveling valve controls and maintains a HORIZONTAL position of the bucket while raising or lowering the boom.(3) Bucket Control Valve

    The bucket control valve consists of 3-position, 6-connection, no detent spring center type spool, a valve housing,load check valve, etc.. This valve connects to A2 and B2 port and controls oil flow to the bucket cylinder.

    P : P Port (Pump Port)T : T Port (Tank Port)

    P.B.: P.B. Port (Power Beyond Port)

    A1 : A1 Port (Connected Boom Bottom Cylinder)

    A2 : A2 Port (Connected Bucket Rod Cylinder)

    B1 : B1 Port (Connected Boom Rod Cylinder)

    B2 : B2 Port (Connected Bucket Bottom Cylinder)

    a-a : Section a-ab-b : Section b-bc-c : Bucket Sectiond-d : Sequence Section

    e-e : Self-leveling Sectionf-f : Divider Sectiong-g : Boom Section

    KiSC issued 08, 2008 A

  • M-14

    LA1403, WSM FRONT LOADER

    [3] OPERATION Control Lever at NEUTRAL Position (Figure 1)

    The following section explains illustration figure 1, 2, 3 and 4.The oil discharged from the hydraulic pump flows into the valve through P port (1). When each spool is in neutral

    condition, the center by-pass passage (4) can not be shut off with spool. The incoming oil goes through the centerby-pass passage (4) in the boom section, divider section, self-leveling section, sequence section and the center by-pass passage of bucket spool (25), then is discharged through P.B. port (26).

    (1) P Port(2) Load Check Valve(3) Boom Spool(4) Center By-pass Passage(5) Passage A(6) Passage B(7) Raising Adjuster(8) Lowering Adjuster(9) Raising Divider Spool

    (10) Lowering Divider Spool(11) Passage C

    (12) Passage D(13) Raising Overload Relief Valve(14) Lowering Overload Relief

    Valve(15) Self-leveling Spool(16) Passage E(17) Passage F(18) Check Valve(19) Check Valve(20) Passage G(21) Passage H

    (22) Lowering Sequence Spool(23) Raising Sequence Spool(24) Load Check Valve(25) Bucket Spool(26) P.B. Port(27) T Port(28) Boom Cylinder(29) Bucket Cylinder(30) Main Relief Valve

    P : P Port (Pump Port)P.B.: P.B. Port (Power Beyond

    Port)

    T : T Port (Tank Port)A1 : A1 Port (Connected Boom

    Bottom Cylinder)A2 : A2 Port (Connected Bucket

    Rod Cylinder)B1 : B1 Port (Connected Boom

    Rod Cylinder)B2 : B2 Port (Connected Bucket

    Bottom Cylinder)1 to 10 : Oil Flow(a) Low Pressure

    KiSC issued 08, 2008 A

  • M-15

    LA1403, WSM FRONT LOADER

    Control Lever at NEUTRAL Position (Figure 2)

    (1) P Port(3) Boom Spool(4) Center By-pass Passage

    (25) Bucket Spool(26) P.B. Port

    P : P Port (Pump Port)T : T Port (Tank Port)

    P.B.: P.B. Port (Power Beyond Port)

    a-a : Section a-ab-b : Section b-b(a) Low Pressure1 to 10 : Oil Flow

    KiSC issued 08, 2008 A

  • M-16

    LA1403, WSM FRONT LOADER

    Control Lever at NEUTRAL Position (Figure 3)

    (25) Bucket Spool A2 : A2 Port (Connected Bucket Rod Cylinder)

    B2 : B2 Port (Connected Bucket Bottom Cylinder)

    c-c : Bucket Sectiond-d : Sequence Sectione-e : Self-leveling Section

    (a) Low Pressure1 to 10 : Oil Flow

    KiSC issued 08, 2008 A

  • M-17

    LA1403, WSM FRONT LOADER

    Control Lever at NEUTRAL Position (Figure 4)

    (1) P Port(3) Boom Spool(4) Center By-pass Passage

    P : P Port (Pump Port) A1 : A1 Port (Connected Boom Bottom Cylinder)

    B1 : B1 Port (Connected Boom Rod Cylinder)

    f-f : Divider Sectiong-g : Boom Section(a) Low Pressure1 to 10 : Oil Flow

    KiSC issued 08, 2008 A

  • M-18

    LA1403, WSM FRONT LOADER

    Boom Raising (Figure 1)

    The following section explains illustration figure 1, 2, 3 and 4.When the boom spool (3) is pushed in with the self-leveling spool (15) pushed in, the hydraulic oil flowing from P

    port (1) is discharged through the opened A1 port via the load check valve (2) because the center by-pass passage(4) is shut off, and is supplied to the boom cylinder bottom side and acts in the direction extending the boom cylinder(28).

    Since the boom cylinder (28) extends, the oil in the rod side flows into the valve through B1 port, and is led into thepassage A (5).

    At this time, all the oil does not go to the raising divider spool (9) (Refer to the f-f.) but is led to the center by-passpassage (4) because the passage A (5) is connected to the center by-pass passage (4) via the self-leveling spool (15).

    Therefore, the hydraulic oil is not supplied to the bucket cylinder (29), and the boom is operated independently.

    (1) P Port(2) Load Check Valve(3) Boom Spool(4) Center By-pass Passage

    (5) Passage A(9) Raising Divider Spool

    (15) Self-leveling Spool

    (28) Boom Cylinder(29) Bucket Cylinder

    1 to 13 : Oil Flow(a) Low Pressure(b) Middle Pressure

    KiSC issued 08, 2008 A

  • M-19

    LA1403, WSM FRONT LOADER

    Boom Raising (Figure 2)

    (3) Boom Spool(5) Passage A

    (9) Raising Divider Spool(15) Self-leveling Spool

    P : P Port (Pump Port)T : T Port (Tank Port)

    P.B.: P.B. Port (Power Beyond Port)

    a-a : Section a-ab-b : Section b-b(a) Low Pressure(b) Middle Pressure1 to 13 : Oil Flow

    KiSC issued 08, 2008 A

  • M-20

    LA1403, WSM FRONT LOADER

    Boom Raising (Figure 3)

    (15) Self-leveling Spool A2 : A2 Port (Connected Bucket Rod Cylinder)

    B2 : B2 Port (Connected Bucket Bottom Cylinder)

    c-c : Bucket Sectiond-d : Sequence Sectione-e : Self-leveling Section

    (a) Low Pressure1 to 13 : Oil Flow

    KiSC issued 08, 2008 A

  • M-21

    LA1403, WSM FRONT LOADER

    Boom Raising (Figure 4)

    (1) P Port(2) Load Check Valve(3) Boom Spool(9) Raising Divider Spool

    A1 : A1 Port (Connected Boom Bottom Cylinder)

    B1 : B1 Port (Connected Boom Rod Cylinder)

    P : P Port (Pump Port)f-f : Divider Sectiong-g: Boom Section

    (a) Low Pressure(b) Middle Pressure1 to 13 : Oil Flow

    KiSC issued 08, 2008 A

  • M-22

    LA1403, WSM FRONT LOADER

    Self-leveling on Boom Raising (Figure 1)

    The following section explains illustration figure 1, 2, 3 and 4.When the boom spool (3) is pushed in, the center by-pass passage (4) is shut off. The hydraulic oil entering P port

    (1) flows to the load check valve (2) and to the opened A1 port. Since the boom cylinder extends, the hydraulic oil inthe rod side flows into the valve through B1 port and is led to the passage A (5).

    The hydraulic oil is divided to two flows. The most part of the hydraulic oil is directly led to the raising divider spool(9) via the raising adjuster (7) (Refer to the a-a.).

    The divider (9) divides the oil flows to the bucket cylinder (29) and the surplusing oil flows to P.B. port (26)depending on the flow division ratio.

    The hydraulic oil is supplied to the passage C (11), the check valve (18) and the B2 port of the bucket cylinder (29).As a result, the bucket cylinder (29) is extended, and the bucket (pullet fork) is kept HORIZONTAL.

    As the bucket cylinder extends, the oil in the rod side flows into the valve through A2 port, and is led into thepassage H (21) and discharged to P.B. port (26) through the raising sequence spool (23) which is operated with thepressure in the bucket cylinder bottom side.

    (1) P Port(2) Load Check Valve(3) Boom Spool(4) Center By-pass Passage(5) Passage A

    (7) Raising Adjuster(9) Raising Divider Spool

    (11) Passage C(18) Check Valve(21) Passage H

    (23) Raising Sequence Spool(26) P.B. Port(28) Boom Cylinder(29) Bucket Cylinder

    1 to 22 : Oil Flow(a) Low Pressure(b) Middle Pressure(c) High Pressure

    KiSC issued 08, 2008 A

  • M-23

    LA1403, WSM FRONT LOADER

    Self-leveling on Boom Raising (Figure 2)

    (1) P Port(3) Boom Spool(7) Raising Adjuster(9) Raising Divider Spool

    (11) Passage C

    (13) Raising Overload Relief Valve(18) Check Valve(21) Passage H(23) Raising Sequence Spool(26) P.B. Port

    P : P Port (Pump Port)T : T Port (Tank Port)

    P.B.: P.B. Port (Power Beyond Port)

    1 to 22 : Oil Flow

    a-a : Section a-ab-b : Section b-b(a) Low Pressure(b) Middle Pressure(c) High Pressure

    KiSC issued 08, 2008 A

  • M-24

    LA1403, WSM FRONT LOADER

    Self-leveling on Boom Raising (Figure 3)

    (18) Check Valve(21) Passage H(23) Raising Sequence Spool

    A2 : A2 Port (Connected Bucket Rod Cylinder)

    B2 : B2 Port (Connected Bucket Bottom Cylinder)

    c-c : Bucket Sectiond-d : Sequence Sectione-e : Self-leveling Section

    (a) Low Pressure(b) Middle Pressure1 to 22 : Oil Flow

    KiSC issued 08, 2008 A

  • M-25

    LA1403, WSM FRONT LOADER

    Self-leveling on Boom Raising (Figure 4)

    (1) P Port(2) Load Check Valve(3) Boom Spool(5) Passage A(7) Raising Adjuster(9) Raising Divider Spool

    A1 : A1 Port (Connected Boom Bottom Cylinder)

    B1 : B1 Port (Connected Boom Rod Cylinder)

    P : P Port (Pump Port)f-f : Divider Sectiong-g: Boom Section

    (a) Low Pressure(b) Middle Pressure(c) High Pressure1 to 22 : Oil Flow

    KiSC issued 08, 2008 A

  • M-26

    LA1403, WSM FRONT LOADER

    Boom Raising with Bucket Cylinder Extended (Figure 1)

    The following section explains illustration figure 1, 2, 3 and 4.When the boom spool (3) is pushed in, the center by-pass passage (4) is shut off. The hydraulic oil entering P port

    (1) flows to the load check valve (2) and to the opened A1 port. Since the boom cylinder extends, the hydraulic oil inthe rod side flows into the valve through B1 port and is led to the passage A (5).

    The hydraulic oil is divided to two flows. The most part of the hydraulic oil is directly led to the raising divider spool(9) via the raising adjuster (7) (Refer to the a-a.).

    The divider (9) divides the oil flows to the bucket cylinder (29) and the surplusing oil flows to P.B. port (26)depending on the flow division ratio.

    The hydraulic oil is supplied to the passage C (11), the check valve (18) and the B2 port of the bucket cylinder (29).As a result, the bucket cylinder (29) is extended, and the bucket (pullet fork) is kept HORIZONTAL.

    As the bucket cylinder extends, the oil in the rod side flows into the valve through A2 port, and is led into thepassage H (21) and discharged to P.B. port (26) through the raising sequence spool (23) which is operated with thepressure in the bucket cylinder bottom side.

    When the bucket cylinder extends and reaches the stroke end during operation of the boom and DUMP, the raisingoverload relief valve (13) which is installed at the passage C (11) is opened and the hydraulic oil is led to the T port(27). As a result, the boom can be kept RAISING.

    (1) P Port(2) Load Check Valve(3) Boom Spool(4) Center By-pass Passage(5) Passage A

    (7) Raising Adjuster(9) Raising Divider Spool

    (11) Passage C(13) Raising Overload Relief Valve(18) Check Valve

    (21) Passage H(23) Raising Sequence Spool(26) P.B. Port(27) T Port(28) Boom Cylinder(29) Bucket Cylinder

    1 to 17 : Oil Flow(a) Low Pressure(b) Middle Pressure(c) High Pressure

    KiSC issued 08, 2008 A

  • M-27

    LA1403, WSM FRONT LOADER

    Boom Raising with Bucket Cylinder Extended (Figure 2)

    (1) P Port(3) Boom Spool(4) Center By-pass Passage(7) Raising Adjuster(9) Raising Divider Spool

    (11) Passage C(18) Check Valve(21) Passage H(26) P.B. Port(27) T Port

    P : P Port (Pump Port)T : T Port (Tank Port)

    P.B. : P.B. Port (Power Beyond Port)

    1 to 17 : Oil Flow

    a-a : Section a-ab-b : Section b-b(a) Low Pressure(b) Middle Pressure(c) High Pressure

    KiSC issued 08, 2008 A

  • M-28

    LA1403, WSM FRONT LOADER

    Boom Raising with Bucket Cylinder Extended (Figure 3)

    (11) Passage C(13) Raising Overload Relief Valve(18) Check Valve(23) Raising Sequence Spool

    A2 : A2 Port (Connected Bucket Rod Cylinder)

    B2 : B2 Port (Connected Bucket Bottom Cylinder)

    c-c : Bucket Sectiond-d : Sequence Sectione-e : Self-leveling Section

    (a) Low Pressure(c) High Pressure1 to 17 : Oil Flow

    KiSC issued 08, 2008 A

  • M-29

    LA1403, WSM FRONT LOADER

    Boom Raising with Bucket Cylinder Extended (Figure 4)

    (2) Load Check Valve(3) Boom Spool(5) Passage A(7) Raising Adjuster(9) Raising Divider Spool

    A1 : A1 Port (Connected Boom Bottom Cylinder)

    B1 : B1 Port (Connected Boom Rod Cylinder)

    P : P Port (Pump Port)f-f : Divider Sectiong-g: Boom Section

    (a) Low Pressure(b) Middle Pressure(c) High Pressure1 to 17 : Oil Flow

    KiSC issued 08, 2008 A

  • M-30

    LA1403, WSM FRONT LOADER

    Boom Lowering (Figure 1)

    The following section explains illustration figure 1, 2, 3 and 4.When the boom spool (3) is pulled out with the self-leveling spool (15) pushed in, the hydraulic oil flowing from P

    port (1) is discharged through the opened B1 port via the load check valve (2) because the center by-pass passage(4) is shut off. Oil is supplied to the boom cylinder rod side and acts in the direction retracting the boom cylinder (28).

    As the boom cylinder (28) retracts, the oil in the bottom side flows into the valve through A1 port, and is led intothe passage B (6).

    At this time, all the oil is not led to the lowering divider spool (10) but is led to the center by-pass passage (4)because the passage B (6) is connected to the center by-pass passage (4) via the self-leveling spool (15).

    Therefore, the oil is not supplied to the bucket cylinder (29), and the boom is operated independently.When the boom cylinder (28) retracts and reaches the stroke end, the tractor main relief valve is activated, and the

    pressure at P port (1) can be kept at the set pressure by discharging the hydraulic oil from the pump into the tank.

    (1) P Port(2) Load Check Valve(3) Boom Spool

    (4) Center By-pass Passage(6) Passage B

    (10) Lowering Divider Spool

    (15) Self-leveling Spool(28) Boom Cylinder(29) Bucket Cylinder

    1 to 11 : Oil Flow(a) Low Pressure(b) Middle Pressure

    KiSC issued 08, 2008 A

  • M-31

    LA1403, WSM FRONT LOADER

    Boom Lowering (Figure 2)

    (1) P Port(3) Boom Spool(4) Center By-pass Passage(6) Passage B

    (15) Self-leveling Spool

    P : P Port (Pump Port)T : T Port (Tank Port)

    P.B. : P.B. Port (Power Beyond Port)

    a-a : Section a-ab-b : Section b-b

    (a) Low Pressure(b) Middle Pressure1 to 11 : Oil Flow

    KiSC issued 08, 2008 A

  • M-32

    LA1403, WSM FRONT LOADER

    Boom Lowering (Figure 3)

    (15) Self-leveling Spool A2 : A2 Port (Connected Bucket Rod Cylinder)

    B2 : B2 Port (Connected Bucket Bottom Cylinder)

    c-c : Bucket Sectiond-d : Sequence Sectione-e : Self-leveling Section

    (a) Low Pressure1 to 11 : Oil Flow

    KiSC issued 08, 2008 A

  • M-33

    LA1403, WSM FRONT LOADER

    Boom Lowering (Figure 4)

    (1) P Port(2) Load Check Valve(3) Boom Spool(6) Passage B

    (10) Lowering Divider Spool

    A1 : A1 Port (Connected Boom Bottom Cylinder)

    B1 : B1 Port (Connected Boom Rod Cylinder)

    P : P Port (Pump Port)f-f : Divider Sectiong-g: Boom Section

    (a) Low Pressure(b) Middle Pressure1 to 11 : Oil Flow

    KiSC issued 08, 2008 A

  • M-34

    LA1403, WSM FRONT LOADER

    Self-leveling on Boom Lowering (Figure 1)

    The following section explains illustration figure 1, 2, 3 and 4.When the boom spool (3) is pulled out the center by-pass passage (4) is shut off. The hydraulic oil entering P port

    (1) flows to the load check valve (2) and to the opened B1 port. Since the boom cylinder retracts (28), the hydraulicoil in the bottom side flows into the valve through A1 port and is led to the passage B (6).

    The hydraulic oil is divided to two flows. The most part of the hydraulic oil is directly led to the lowering dividerspool (10) via the lowering adjuster (8) (Refer to the a-a.).

    The divider divides the oil flows to the bucket cylinder (29) and the surplusing oil flows to P.B. port (26) dependingon the flow division ratio.

    The hydraulic oil supplied to the passage D (12), the check valve (19) and the A2 port of the bucket cylinder (29).As a result, the bucket cylinder (29) is retracted, and the bucket (pallet fork) is kept HORIZONTAL.As the bucket cylinder (29) retracts, the oil in the bottom side flows into the valve through B2 port, and is led into

    the passage G (20) and discharged to P.B. port (26) through the lowering sequence spool (22) which is operated withthe pressure in the bucket cylinder rod side.

    (1) P Port(2) Load Check Valve(3) Boom Spool(4) Center By-pass Passage(6) Passage B

    (8) Lowering Adjuster(10) Lowering Divider Spool(12) Passage D(19) Check Valve(20) Passage G

    (22) Lowering Sequence Spool(26) P.B. Port(28) Boom Cylinder(29) Bucket Cylinder

    1 to 19 : Oil Flow(a) Low Pressure(b) Middle Pressure(c) High Pressure

    KiSC issued 08, 2008 A

  • M-35

    LA1403, WSM FRONT LOADER

    Self-leveling on Boom Lowering (Figure 2)

    (1) P Port(3) Boom Spool(4) Center By-pass Passage(8) Lowering Adjuster

    (10) Lowering Divider Spool(22) Lowering Sequence Spool(26) P.B. Port

    P : P Port (Pump Port)T : T Port (Tank Port)

    P.B.: P.B. Port (Power Beyond Port)

    1 to 19 : Oil Flow

    a-a :Section a-ab-b :Section b-b(a) Low Pressure(b) Middle Pressure(c) High Pressure

    KiSC issued 08, 2008 A

  • M-36

    LA1403, WSM FRONT LOADER

    Self-leveling on Boom Lowering (Figure 3)

    (22) Lowering Sequence Spool A2 : A2 Port (Connected Bucket Rod Cylinder)

    B2 : B2 Port (Connected Bucket Bottom Cylinder)

    c-c : Bucket Sectiond-d : Sequence Sectione-e : Self-leveling Section

    (a) Low Pressure(b) Middle Pressure(c) High Pressure1 to 19 : Oil Flow

    KiSC issued 08, 2008 A

  • M-37

    LA1403, WSM FRONT LOADER

    Self-leveling on Boom Lowering (Figure 4)

    (1) P Port(2) Load Check Valve(3) Boom Spool(6) Passage B (8) Lowering Adjuster

    (10) Lowering Divider Spool

    A1 : A1 Port (Connected Boom Bottom Cylinder)

    B1 : B1 Port (Connected Boom Rod Cylinder)

    P : P Port (Pump Port)f-f : Divider Sectiong-g: Boom Section

    (a) Low Pressure(b) Middle Pressure(c) High Pressure1 to 19 : Oil Flow

    KiSC issued 08, 2008 A

  • M-38

    LA1403, WSM FRONT LOADER

    Boom Lowering with Bucket Cylinder Fully Retracted (Figure 1)

    The following section explains illustration figure 1, 2, 3 and 4.When the boom spool (3) is pulled out the center by-pass passage (4) is shut off. The hydraulic oil entering P port

    (1) flows to the load check valve (2) and to the opened B1 port. Since the boom cylinder retracts (28), the hydraulicoil in the bottom side flows into the valve through A1 port and is led to the passage B (6).

    The hydraulic oil is divided to two flows. The most part of the hydraulic oil is directly led to the lowering dividerspool (10) via the lowering adjuster (8) (Refer to the a-a.).

    The divider divides the oil flows to the bucket cylinder (29) and the surplusing oil flows to P.B. port (26) dependingon the flow division ratio.

    The hydraulic oil is supplied to the passage D (12), the check valve (19) and the A2 port of the bucket cylinder (29).As a result, the bucket cylinder (29) is retracted, and the bucket (pallet fork) is kept HORIZONTAL.As the bucket cylinder (28) retracts, the oil in the bottom side flows into the valve through B2 port, and is led into

    the passage G (20) and discharged to P.B. port (26) through the lowering sequence spool (22) which is operated withthe pressure in the bucket cylinder rod side.

    When the bucket cylinder (29) retracts and reaches the stroke end during operation of the boom and ROLL-BACK,the lowering overload relief valve (14) which is installed at the passage D (12) is opened and the hydraulic oil is led toT port (27). As a result, the boom can be kept LOWERING.

    (1) P Port(2) Load Check Valve(3) Boom Spool(4) Center By-pass Passage(6) Passage B

    (8) Lowering Adjuster(10) Lowering Divider Spool(12) Passage D(14) Lowering Overload Relief

    Valve

    (19) Check Valve(20) Passage G(22) Lowering Sequence Spool(26) P.B. Port(27) T Port

    (28) Boom Cylinder(29) Bucket Cylinder1 to 20 : Oil Flow(a) Low Pressure(b) Middle Pressure(c) High Pressure

    KiSC issued 08, 2008 A

  • M-39

    LA1403, WSM FRONT LOADER

    Boom Lowering with Bucket Cylinder Fully Retracted (Figure 2)

    (3) Boom Spool(4) Center By-pass Passage(8) Lowering Adjuster

    (10) Lowering Divider Spool

    (19) Check Valve(20) Passage G(22) Lowering Sequence Spool(26) P.B. Port(27) T Port

    P : P Port (Pump Port)T : T Port (Tank Port)

    P.B.: P.B. Port (Power Beyond Port)

    1 to 20 : Oil Flow

    a-a : Section a-ab-b : Section b-b(a) Low Pressure(b) Middle Pressure(c) High Pressure

    KiSC issued 08, 2008 A

  • M-40

    LA1403, WSM FRONT LOADER

    Boom Lowering with Bucket Cylinder Fully Retracted (Figure 3)

    (14) Lowering Overload Relief Valve

    (19) Check Valve(20) Passage G(22) Lowering Sequence Spool

    A2 : A2 Port (Connected Bucket Rod Cylinder)

    B2 : B2 Port (Connected Bucket Bottom Cylinder)

    c-c : Bucket Sectiond-d : Sequence Sectione-e : Self-leveling Section

    (a) Low Pressure(b) Middle Pressure1 to 20 : Oil Flow

    KiSC issued 08, 2008 A

  • M-41

    LA1403, WSM FRONT LOADER

    Boom Lowering with Bucket Cylinder Fully Retracted (Figure 4)

    (1) P Port(2) Load Check Valve(3) Boom Spool(6) Passage B (8) Lowering Adjuster

    (10) Lowering Divider Spool(12) Passage D

    A1 : A1 Port (Connected Boom Bottom Cylinder)

    B1 : B1 Port (Connected Boom Rod Cylinder)

    P : P Port (Pump Port)f-f : Divider Sectiong-g: Boom Section

    (a) Low Pressure(b) Middle Pressure(c) High Pressure1 to 20 : Oil Flow

    KiSC issued 08, 2008 A

  • M-42

    LA1403, WSM FRONT LOADER

    Boom Floating (Figure 1)

    The following section explains illustration figure 1, 2, 3 and 4.When the boom spool (3) is pulled out and switched into the detent position, all the hydraulic oil from P port (1) is

    discharged through P.B. port (26) via the center by-pass passage (4) because the center by-pass passage (4) isopened.

    On the other hand, because the A1 port and B1 port are connected to the T port (27), respectively, the oil in therod side / bottom side of the boom cylinder can flow between the rod side and the bottom side freely, so any stroke ofboom cylinder can be made depending on external force (topography).

    *The same action is performed in both cases when the self-leveling is ON or OFF.

    (1) P Port(3) Boom Spool(4) Center By-pass Passage

    (27) T Port(28) Boom Cylinder(29) Bucket Cylinder

    1 to 14 : Oil Flow (a) Low Pressure(b) Middle Pressure

    KiSC issued 08, 2008 A

  • M-43

    LA1403, WSM FRONT LOADER

    Boom Floating (Figure 2)

    (1) P Port(3) Boom Spool(4) Center By-pass Passage

    (26) P.B. Port(27) T Port

    P : P Port (Pump Port)T : T Port (Tank Port)

    P.B.: P.B. Port (Power Beyond Port)

    a-a : Section a-ab-b : Section b-b(a) Low Pressure(b) Middle Pressure1 to 14 : Oil Flow

    KiSC issued 08, 2008 A

  • M-44

    LA1403, WSM FRONT LOADER

    Boom Floating (Figure 3)

    A2 : A2 Port (Connected Bucket Rod Cylinder)

    B2 : B2 Port (Connected Bucket Bottom Cylinder)

    c-c : Bucket Sectiond-d : Sequence Sectione-e : Self-leveling Section

    (a) Low Pressure(b) Middle Pressure1 to 14 : Oil Flow

    KiSC issued 08, 2008 A

  • M-45

    LA1403, WSM FRONT LOADER

    Boom Floating (Figure 4)

    (1) P Port(3) Boom Spool

    A1 : A1 Port (Connected Boom Bottom Cylinder)

    B1 : B1 Port (Connected Boom Rod Cylinder)

    P : P Port (Pump Port)f-f : Divider Sectiong-g: Boom Section

    (a) Low Pressure(b) Middle Pressure1 to 14 : Oil Flow

    KiSC issued 08, 2008 A

  • M-46

    LA1403, WSM FRONT LOADER

    Bucket (Roll-Back) (Figure 1)

    The following section explains illustration figure 1, 2, 3 and 4.When the bucket spool (25) is pulled out, the hydraulic oil flowing from P port (1) passes through the center by-

    pass passage (4) (Refer to the b-b.) via the load check valve (24) and is discharged into the opened A2 port. The oilis then supplied to the bucket cylinder rod side and acts in the direction of retracting the bucket cylinder (29).

    As the bucket cylinder (29) retracts, the oil in the bottom side flows into the valve through B2 port, and is dischargedfrom the T port (27).

    When the bucket cylinder (29) retracts and reaches the stroke end during roll-back operation, the tractor main reliefvalve operates and retains the pressure of P port (1) at the set pressure by discharging hydraulic oil from the pumpinto the tank.

    (1) P Port(4) Center By-pass Passage

    (24) Load Check Valve(25) Bucket Spool

    (27) T Port(29) Bucket Cylinder

    1 to 10 : Oil Flow(a) Low Pressure(b) Middle Pressure

    KiSC issued 08, 2008 A

  • M-47

    LA1403, WSM FRONT LOADER

    Bucket (Roll-Back) (Figure 2)

    (4) Center By-pass Passage(25) Bucket Spool(27) T Port

    P : P Port (Pump Port)P.B.: P.B. Port (Power Beyond

    Port)

    T : T Port (Tank Port)1 to 10 : Oil Flow

    a-a : Section a-ab-b : Section b-b(a) Low Pressure(b) Middle Pressure

    KiSC issued 08, 2008 A

  • M-48

    LA1403, WSM FRONT LOADER

    Bucket (Roll-Back) (Figure 3)

    (24) Load Check Valve(25) Bucket Spool

    A2 : A2 Port (Connected Bucket Rod Cylinder)

    B2 : B2 Port (Connected Bucket Bottom Cylinder)

    c-c : Bucket Sectiond-d : Sequence Sectione-e : Self-leveling Section

    (a) Low Pressure(b) Middle Pressure1 to 10 : Oil Flow

    KiSC issued 08, 2008 A

  • M-49

    LA1403, WSM FRONT LOADER

    Bucket (Roll-Back) (Figure 4)

    (1) P Port A1 : A1 Port (Connected Boom Bottom Cylinder)

    B1 : B1 Port (Connected Boom Rod Cylinder)

    P : P Port (Pump Port)f-f : Divider Sectiong-g: Boom Section

    (a) Low Pressure(b) Middle Pressure1 to 10 : Oil Flow

    KiSC issued 08, 2008 A

  • M-50

    LA1403, WSM FRONT LOADER

    Bucket (Dump) (Figure 1)

    The following section explains illustration figure 1, 2, 3 and 4.When the bucket spool (25) is pushed in, the hydraulic oil from P port (1) passes through the center by-pass

    passage (4) (Refer to the b-b.) via the load check valve (24) and is discharged into the opened A2 and B2 ports. Asa result, the oil is supplied to the rod side and the bottom side of the bucket cylinder, and acts in the extending directionaccording to the cylinder area ratio.

    As the bucket cylinder extends, the oil in the rod side flows into the valve through A2 port, and joins the oil from Pport (1) and is led to the bottom side again (Refer to the c-c.).

    During this operation, the oil is not discharged through P.B. port (26) and T port (27).When the bucket cylinder extends and reaches the stroke end during operation of the dump, the tractor main relief

    valve operates and retains the pressure of P port (1) at the set pressure by discharging hydraulic oil from the pumpinto the tank.

    (1) P Port(4) Center BY-pass Passage

    (24) Load Check Valve

    (25) Bucket Spool(26) P.B. Port

    (27) T Port(29) Bucket Cylinder

    1 to 10 : Oil Flow(a) Low Pressure

    KiSC issued 08, 2008 A

  • M-51

    LA1403, WSM FRONT LOADER

    Bucket (Dump) (Figure 2)

    (1) P Port(4) Center By-pass Passage

    (25) Bucket Spool(26) P.B. Port(27) T Port

    P : P Port (Pump Port)T : T Port (Tank Port)

    P.B.: P.B. Port (Power Beyond Port)

    a-a : Section a-ab-b : Section b-b(a) Low Pressure1 to 10 : Oil Flow

    KiSC issued 08, 2008 A

  • M-52

    LA1403, WSM FRONT LOADER

    Bucket (Dump) (Figure 3)

    (24) Load Check Valve(25) Bucket Spool

    A2 : A2 Port (Connected Bucket Rod Cylinder)

    B2 : B2 Port (Connected Bucket Bottom Cylinder)

    c-c : Bucket Sectiond-d : Sequence Sectione-e : Self-leveling Section

    (a) Low Pressure1 to 10 : Oil Flow

    KiSC issued 08, 2008 A

  • M-53

    LA1403, WSM FRONT LOADER

    Bucket (Dump) (Figure 4)

    (1) P Port P : P Port (Pump Port) A1 : A1 Port (Connected Boom Bottom Cylinder)

    B1 : B1 Port (Connected Boom Rod Cylinder)

    f-f : Divider Sectiong-g: Boom Section(a) Low Pressure1 to 10 : Oil Flow

    KiSC issued 08, 2008 A

  • M-54

    LA1403, WSM FRONT LOADER

    [4] RELIEF VALVE(1) Main Relief Valve

    Relief Valve ClosedThe cylinder port P is applied to the seat B in the

    following route : first through the throttle a of the pistonpoppet (1) built in the relief valve poppet (5), secondthrough the spring chamber A, and then through thecircular clearance between the adjusting screw and thepiston poppet (1). This cylinder port P works to open thepilot poppet (2). Because the piston spring (3) has notreached the set pressure, however, the valve stays shut.In this way the seat remains intact and the relief valvepoppet (5) stays shut.

    W10237990

    Relief Valve OperationWhen the P port has reached the set pressure of the

    piston spring (3), the pressure oil in the spring chamberA opens the pilot poppet (2) and flows through the drainpassage into the tank passage. This lowers the pressurein the spring chamber A, and the pressure differenceacross the throttle a moves the relief valve poppet (5) tothe right. Now the seat of the relief valve poppet (5) getsopen. The pressure oil then flows from this seat into thetank, and the circuit pressure is kept at the pressure levelset by the main relief valve.

    W10240770

    (1) Piston Poppet(2) Pilot Poppet(3) Piston Spring(4) Adjusting Screw(5) Relief Valve Poppet

    P : From PumpT : To TankA : ChamberB : SeatY : Middle Pressurea : Throttle

    (1) Piston Poppet(2) Pilot Poppet(3) Piston Spring(4) Adjusting Screw(5) Relief Valve Poppet

    P : From PumpT : To TankA : ChamberX : Low PressureY : Middle PressureZ : High Pressurea : Throttle

    KiSC issued 08, 2008 A

  • M-55

    LA1403, WSM FRONT LOADER

    (2) Overload Relief ValveOverload relief valve in this control valve is a

    combination valve combining a relief operation and anti-cavitation operation.

    Relief OperationWhen the control valve is in the neutral position, both

    cylinder ports of control valve are blocked by the spool.If an external load is imposed on the cylinder, pressurebuilds in the circuit.

    When the pressure exceeds the set level of theoverload relief valve, the relief valve opens and the oilreturns to tank. In this way, the hydraulic circuit andactuator are protected from excessive pressure.

    Anti-cavitation OperationOverload relief valve also has anti-void function. If

    negative pressure takes place in the circuit, the oil is fedfrom the tank to eliminate the negative pressure.

    W1023498

    Relief Operation[When the actuator port pressure is lower than thesetting]

    The cylinder port HP is applied to the seat B in thefollowing route : first through the throttle a of the pistonpoppet (1) built in the relief valve poppet (5), secondthrough the spring chamber A, and then through thecircular clearance between the adjusting screw (9) andthe piston poppet (1). This cylinder port HP works toopen the pilot poppet (2). Because the piston spring (3)has not reached the set pressure, however, the valvestays shut. In this way the seat remains intact and therelief valve poppet (5) stays shut.

    W1024073

    (1) Overload Relief Valve(2) Control Valve(3) Housing(4) Check Valve Poppet(5) Relief Valve Poppet(6) Piston Spring

    (7) Piston Poppet(8) Lock Nut(9) Adjusting Screw

    (10) Pilot Spring(11) Pilot Poppet(12) Pilot Section

    (1) Piston Poppet(2) Pilot Poppet(3) Piston Spring(4) Adjusting Screw(5) Relief Valve Poppet

    HP : High PressureLP : Low PressureA : ChamberB : Seata : Throttle

    KiSC issued 08, 2008 A

  • M-56

    LA1403, WSM FRONT LOADER

    [When the actuator port pressure is higher than thesetting]

    When the cylinder port HP has reached the setpressure of the piston spring (3), the pressure oil in thespring chamber A opens the pilot poppet (2) and flowsthrough the drain passage into the tank passage. Thislowers the pressure in the spring chamber A, and thepressure difference across the throttle a moves the reliefvalve poppet (5) to the right. Now the seat of the reliefvalve poppet (5) gets open. The pressure oil then flowsfrom this seat into the tank, and the circuit pressure iskept at the pressure level set by the overload relief valve.

    Oil temperature : 45 to 55 C 113 to 131 F

    W1024163

    Anti-cavitation OperationThis valve, in operation, prevents a condition so

    called cavitation that arises in the cylinder port HPwhere fluid is not entirely filling up.

    That is, this relief valve is combined with an anti-cavitation function for supplying oil.

    The pressure oil at the tank port LP opens the checkvalve poppet, allowing oil to flow through the tank port toprevent negative pressure from being generated in thecylinder.

    W1024467

    Relief valve setting pressure

    Raising relief valve16.3 to 16.8 MPa167 to 171 kgf/cm22370 to 2430 psi

    Lowering relief valve18.6 to 19.1 MPa190 to 195 kgf/cm22700 to 2783 psi

    (1) Piston Poppet(2) Pilot Poppet(3) Piston Spring(4) Adjusting Screw(5) Relief Valve Poppet

    HP :High PressureLP :Low PressureA : Chambera : Throttle

    (1) Check Valve Poppet(2) Piston Spring(3) Pilot Poppet(4) Relief Valve Poppet(5) Piston Poppet

    LP :Low PressureHP :High Pressure

    KiSC issued 08, 2008 A

  • M-57

    LA1403, WSM FRONT LOADER

    3. BOOM CYLINDER AND BUCKET CYLINDER

    Both boom cylinder and bucket cylinder consist of head (4), cylinder tube (3), piston rod (5), piston (2), and otherparts as shown in the figure above. They are single-rod double acting cylinder in which the reciprocating motion ofthe piston is controlled by hydraulic force applied to both of its ends.

    Cylinder Specifications

    W1025274

    (1) Nut(2) Piston

    (3) Cylinder Tube (4) Head (5) Piston Rod

    LA1403Boom Cylinder Cylinder I.D. 70 mm (2.76 in.)

    Rod O.D. 40 mm (1.57 in.)Stroke 606 mm (23.9 in.)

    Bucket Cylinder Cylinder I.D. 70 mm (2.76 in.)Rod O.D. 40 mm (1.57 in.)Stroke 516.5 mm (20.3 in.)

    KiSC issued 08, 2008 A

  • M-58

    LA1403, WSM FRONT LOADER

    4. 3RD FUNCTION VALVE (OPTION)[1] HYDRAULIC CIRCUIT

    If 3rd function valve assy. (2) is equipped, oil can be controlled to operate another implement.

    (1) Hydraulic Pump(2) 3rd Function Valve Assy.(3) Relief Valve

    (3rd Function Valve)(4) 3rd Function Solenoid Valve

    (5) Boom Cylinder(6) Bucket Cylinder(7) Relief Valve (Main)(8) Front Loader Valve(9) Orifice (Standard Valve Only)

    P : Pump PortPB : Power Beyond Port

    T : Tank Port

    A : A PortA1 : A1 PortA2 : A2 PortB : B Port

    B1 : B1 PortB2 : B2 Port

    KiSC issued 08, 2008 A

  • M-59

    LA1403, WSM FRONT LOADER

    [2] 3RD FUNCTION SOLENOID VALVE OPERATIONSpool at Neutral Position

    1. In neutral, the spool (2) is at the center position with the right and left springs (1) (3).2. Oil from the pump flows from the P port to the PB port.3. The A port and B port are blocked by the spool (2).

    (1) Spring(2) Spool

    (3) Spring A : A PortB : B PortP : Pump Port

    PB :Power Beyond PortT : Tank PortC : To Backhoe Control Valve

    KiSC issued 08, 2008 A

  • M-60

    LA1403, WSM FRONT LOADER

    Button A is pushed (Activation Switch A)

    1. A current passes through the coil (1) while the button A (3) is pressed.2. Therefore the spool (2) is pushed to the right.3. At that time, oil from the P port starts to flow into the A (3) port.4. Oil from the B port flows into the PB port.

    (1) Coil(2) Spool(3) Activation Switch A(4) Activation Switch B

    A : A Port (To Implement)B : B Port (From Implement)

    P : Pump PortPB : Power Beyond Port

    C : To Backhoe Control Valve

    KiSC issued 08, 2008 A

  • M-61

    LA1403, WSM FRONT LOADER

    Button B is pushed (Activation Switch B)

    1. A current passes through the coil (2) while the button B (4) is pressed.2. Therefore the spool (1) is pushed to the left.3. At that time, oil from the P port starts to flow into the B (4) port.4. Oil from the A port flows into the PB port.

    (1) Spool(2) Coil(3) Activation Switch A(4) Activation Switch B

    A : A Port (From Implement)B : B Port (To Implement)

    P : Pump PortPB : Power Beyond Port

    C : To Backhoe Control Valve

    KiSC issued 08, 2008 A

  • M-62

    LA1403, WSM FRONT LOADER

    [3] ELECTRICAL CIRCUIT

    Color of Wiring

    W1019456

    (1) Relay 1(2) Relay 2

    (3) Solenoid Valve 1(4) Solenoid Valve 2

    (5) ON - OFF Switch (For 3rd Function Kit)

    (6) Activation Switch A

    (7) Activation Switch B(8) Battery

    B ........... Black BrR ........ Brown / Red WR ........... White / Red

    W .......... White RB ............ Red / Black YR ............. Yellow / Red

    Br .......... Brown

    KiSC issued 08, 2008 A

  • M-63

    LA1403, WSM FRONT LOADER

    5. HYDRAULIC ACCUMULATOR (OPTION)[1] HYDRAULIC CIRCUIT

    If hydraulic accumulator is equipped, the shock when the boom is operated can be alleviated.

    (1) Hydraulic Pump(2) Front Loader Valve (Standard

    Valve)

    (3) Orifice (Standard Valve Only)(4) Boom Cylinder

    (5) Accumulator Valve(6) Accumulator

    (7) Orifice (Self-leveling Valve Only)

    (8) Bucket Cylinder

    KiSC issued 08, 2008 A

  • M-64

    LA1403, WSM FRONT LOADER

    [2] ACCUMULATOR VALVE

    Accumulator valve controls the oil to flow between the boom cylinder (5) and the accumulator (6) or not.

    (1) Accumulator Valve(2) Directional Valve(3) Relief Valve for Bottom Side(4) Relief Valve for Rod Side

    (5) Boom Cylinder(6) Accumulator(7) Orifice (Self-leveling Valve

    Only)

    A1: A1 PortB1: B1 PortA3: A3 PortB3: B3 PortT: Tank PortF: Connected to Front Loader

    [X] Accumulator Valve ON Position

    [Y] Accumulator Valve OFF Position

    (a) Hydraulic Oil

    KiSC issued 08, 2008 A

  • M-65

    LA1403, WSM FRONT LOADER

    [3] HYDRAULIC ACCUMULATOR

    W1022595

    1. The kind of employed accumulator is a diaphragm accumulator.2. The accumulator uses nitrogen gas.3. When pressure in the circuit rises and exceeds the set pressure of the accumulator, a diaphragm is compressed

    and oil is taken into the oil chamber (3).4. Reversely, when the pressure in the circuit drops down below the set pressure, the compressed gas expands to

    make the oil contained in the oil chamber (3) return to the circuit.5. By utilizing this characteristic, it absorbs the pressure from a boom cylinder to alleviate the shock.(Reference)

    W1031964

    (1) Accumulator(2) Gas Chamber(3) Oil Chamber(4) Valve Poppet

    (5) Diaphragm(6) Stopper 1(7) Stopper 2

    [L] Low Pressure[M] Middle Pressure[H] High Pressure

    (a) Low Pressure Oil(b) Middle Pressure Oil(c) High Pressure Oil(d) Low Pressure Gas(e) Middle Pressure Gas(f) High Pressure Gas

    Item Gas Pressure

    Boom cylinder bottom side accumulator gas pressure

    1.9 to 2.1 MPa20 to 21 kgf/cm2280 to 300 psi

    Boom cylinder rod side accumulator gas pressure

    3.9 to 4.1 MPa40 to 41 kgf/cm2570 to 590 psi

    KiSC issued 08, 2008 A

  • M-66

    LA1403, WSM FRONT LOADER

    [4] ACCUMULATOR RELIEF VALVERelief Valve ClosedThis relief valve is suitable for a high pressure and

    large volumetric flow with better pressure overrideperformance than direct acting relief valves.

    This relief valve consists of a pilot valve (4) and mainvalve (8). The pilot valve (4) is a trigger which controlsthe main valve (8).

    When the oil pressure in the circuit is lower than thesetting pressure, the pilot valve (4) and main valve (8)are closed by the spring (3) and (7).

    W10340610

    Relief Valve in OperationAs the oil pressure in the circuit rises, so does the

    pressure in the chamber C. When it reaches the pilotvalve setting pressure, the pilot valve (2) opens. Thisreleases oil in the chamber C to the transmission case.Accordingly the oil in the circuit flows to the chamber Cthrough the passage (5).

    The resulting pressure drop in the chamber Ccauses the main valve (4) open. The oil in the circuit thenflows out to the transmission case, preventing any furtherrise in pressure. The relief valve close again when the oilpressure in the circuit drops below the setting pressure.(Reference)

    W10338830

    (1) Relief Valve Body(2) Adjuster(3) Spring(4) Pilot Valve(5) Valve Seat(6) Sensing Passage

    (7) Spring(8) Main Valve(9) Valve Seat

    (10) Passage

    P : P Port

    Relief valve setting pressure23.1 to 23.5 MPa235 to 240 kgf/cm23350 to 3410 psi

    (1) Spring(2) Pilot Valve(3) Valve Seat(4) Main Valve(5) Passage(6) Valve Seat

    (C) Chamber CP : P PortT : T Port

    KiSC issued 08, 2008 A

  • CONTENTS

    SERVICING

    1. TROUBLESHOOTING ......................................................................................S-12. SERVICING SPECIFICATIONS ......................................................................S-23. TIGHTENING TORQUES (ESPECIALLY SPECIFIED) .................................S-34. DISMOUNTING FRONT LOADER FROM TRACTOR..................................S-45. CHECKING, DISASSEMBLING AND SERVICING........................................S-6

    [1] CHECKING AND ADJUSTING .................................................................S-6(1) Control Valve ........................................................................................S-6(2) Adjusting Self-leveling...........................................................................S-7(3) 3rd Function Valve (Option) ..................................................................S-9

    [2] DISASSEMBLING AND ASSEMBLING..................................................S-12(1) Control Valve Assembly......................................................................S-12(2) Control Valve ......................................................................................S-14(3) Controller and Cables .........................................................................S-19(4) Bucket, Boom and Hydraulic Cylinders...............................................S-20(5) Main Frame and Others ......................................................................S-25(6) Accumulator (Option) ..........................................................................S-27

    [3] SERVICING ..............................................................................................S-28

    KiSC issued 08, 2008 A

  • S-1

    LA1403, WSM FRONT LOADER

    1. TROUBLESHOOTING

    Symptom Probable Cause Solution Reference PageBoom Does Not Rise Control valve malfunctioning Repair or replace S-13

    Boom cylinder defective Repair or replace S-22Control lever cable defective Repair or replace S-19Hydraulic pump malfunctioning Repair or replace Oil filter clogged Clean or replace Relief valve spring damaged Replace S-6Hydraulic hose damaged Replace S-22Relief valve dirty or stuck Clean S-6

    Boom Does Not Lower

    Control valve malfunctioning Repair or replace S-13

    Insufficient Boom Speed

    Boom cylinder tube worn or damaged Replace S-22Boom cylinder piston ring (piston seal and O-ring) worn or damaged

    Replace S-24

    Oil leaks from tube joints Repair Relief valve setting pressure too low Adjust S-6Insufficient transmission fluid Refill G-8Dirty relief valve Clean S-6

    Bucket Does Not Move

    Control valve malfunctioning Repair or replace S-13Bucket cylinder defective Repair or replace S-22Control lever cable defective Repair or replace S-19Hydraulic pump malfunctioning Repair or replace Oil filter clogged Clean or replace Relief valve spring damaged Replace S-6Hydraulic hose damaged Replace S-22Dirty relief valve Clean S-6

    Insufficient Bucket Speed

    Bucket cylinder tube worn or damaged Replace S-22Bucket cylinder piston ring (piston seal and O-ring) worn or damaged

    Replace S-24

    Oil leaks from tube joints Repair Relief valve setting pressure too low Adjust S-6Insufficient transmission fluid Refill G-8Dirty relief valve Clean S-6

    Front End Loader Drops by its Weight

    Boom cylinder tube worn or damaged Replace S-22Boom cylinder piston ring (piston seal and O-ring) worn or damaged

    Replace S-24

    Oil leaks from tube joints Repair Control valve malfunctioning Repair or replace S-13

    KiSC issued 08, 2008 A

  • S-2

    LA1403, WSM FRONT LOADER

    2. SERVICING SPECIFICATIONS

    W1013874

    Item Factory Specification Allowable LimitRelief ValveCondition

    Engine Speed ........ Approx. 2600 min-1 (rpm)

    Oil Temperature ....... 44 to 48 C 110 to 120 F

    Setting Pressure 20.3 to 21.0 MPa207 to 214 kgf/cm22950 to 3045 psi

    Piston Rod Bend 0.25 mm0.0098 in.

    3rd Function Relief Valve (Option)Condition

    Engine Speed ........ Approx. 2600 min-1 (rpm)

    Oil Temperature ....... 45 to 55 C 113 to 131 F

    Setting Pressure 20.1 to 21.0 MPa205 to 215 kgf/cm22920 to 3050 psi

    KiSC issued 08, 2008 A

  • S-3

    LA1403, WSM FRONT LOADER

    3. TIGHTENING TORQUES (ESPECIALLY SPECIFIED)

    W1012736

    Item Nm kgfm lbfftControl valve mounting bolt 48 to 55 4.9 to 5.7 36 to 41Look nut 5.4 to 7.8 0.55 to 0.79 4.0 to 5.7Adaptor and elbow 3/4-16 UNF 48 to 54 4.9 to 5.5 35 to 40Mounting nut (Tie rod : 9.5 mm DIA (3/8 in. DIA)) 45 4.6 33Mounting nut (Tie rod : 7.9 mm DIA (5/16 in. DIA)) 19 1.9 14Relief valve assembly 40.0 to 49.5 4.08 to 5.04 29.5 to 36.5M16 lock nut 51 to 58 5.2 to 5.9 37 to 43Boom and bucket cylinder head 250 to 280 25.5 to 28.5 185 to 206Boom and bucket cylinder piston mounting nut 160 to 200 16.4 to 20.3 119 to 147Main frame mounting bolt (M20) 368 37.5 271Main frame mounting bolt (M18) 319 32.5 235Main frame mounting nut (M18) 343 35.0 253

    KiSC issued 08, 2008 A

  • S-4

    LA1403, WSM FRONT LOADER

    4. DISMOUNTING FRONT LOADER FROM TRACTORCAUTION

    Make sure an approved bucket is attached before removing the loader from the tractor. For removing the loader, choose flat and hard ground, preferably concrete. If the ground surface is soft, place suitable planks on the ground for the bucket and stands. When starting the engine or using the hydraulic control valve, always sit in the operators seat. Make sure the bucket and stands are at ground level.

    Stand1. Raise the boom until the stands (1) can be rotated.2. Stop the engine.3. Remove the spring pins (2) holding the stands (1) to the boom.4. Rotate the stands (1) until the pin on the stand and hole in the

    boom are aligned.Then slide the stands (1) outward and insert the spring pin (2) asshown.

    5. Start the engine and run at idle.6. Dump the bucket approximately 0.35 rad (20 ).7. Lower the boom and raise the front wheels slightly.

    IMPORTANT Lift the weight off the front wheels with the bucket. Do not

    attempt to lift them with the stands (1).8. Stop the engine.

    W1012789

    Side Frame1. Remove the mounting pins from the loader main frame and hold

    them on boom.2. Start the engine and run at idle.3. Slowly move the hydraulic control lever to rollback position to

    raise the loader side frames up and out of the receives of themain frames as shown.

    4. Stop the engine.

    W1014434

    (1) Stand(2) Spring Pin

    (a) 0.35 rad (20 )

    (1) Hydraulic Control Lever

    KiSC issued 08, 2008 A

  • S-5

    LA1403, WSM FRONT LOADER

    Hydraulic Hoses1. Slowly release all hydraulic pressure by moving the hydraulic

    control lever in all directions.2. Disconnect the four hoses with quick couplers at the control valve

    and place them on the right side of the boom.3. Place the protective caps and plugs on the quick coupler ends.4. Start the engine and slowly back the tractor away from the loader.

    W1015095(1) Protective Plug

    KiSC issued 08, 2008 A

  • S-6

    LA1403, WSM FRONT LOADER

    5. CHECKING, DISASSEMBLING AND SERVICING[1] CHECKING AND ADJUSTING(1) Control Valve

    Relief Valve Setting Pressure (Standard Valve Type)1. Remove the hose with quick coupler from A2 port (1) of the

    control valve and set a pressure gauge.2. Start the engine, warm it up at an idle, and then set the engine

    speed. (Refer to the Condition)3. Move the hydraulic control lever to DUMP position, and read the

    pressure gauge indication when a sound indicating the reliefvalve operation is head.

    4. If the pressure is not within the factory specifications, loosen thelock nut (3) then adjust by adjust screw (4).

    Condition Engine speed ........ Approx. 2600 min-1 (rpm) Oil temperature ..... 44 to 48 C

    110 to 120 F

    W1014688

    Relief Valve Setting Pressure (Self-leveling Valve Type)1. Remove the hose with quick coupler from A2 port (1) of the

    control valve and set a pressure gauge.2. Start the engine, warm it up at an idle, and then set the engine

    speed. (Refer to the Condition)3. Move the hydraulic control lever to DUMP position, and read the

    pressure gauge indication when a sound indicating the reliefvalve operation is head.

    4. If the pressure is not within the factory specifications, loosen thelock nut (3) then adjust by adjust screw (4).

    Condition Engine speed ........ Approx. 2600 min-1 (rpm) Oil temperature ..... 44 to 48 C

    110 to 120 F

    W1018944

    Relief valve setting pressure Factory spec.

    20.3 to