l-68 022873 INSTRUCT IONS ELECTRIC-HYDRAULIC GOVERNOR ... · PDF fileINTRODUCTION ., This...
Transcript of l-68 022873 INSTRUCT IONS ELECTRIC-HYDRAULIC GOVERNOR ... · PDF fileINTRODUCTION ., This...
INSTRUCT IONS
for
ELECTRIC-HYDRAULIC GOVERNOR SYSTEM
used on
DIESEL ENGINES
Cummins Engine Company
Model No. V-378-C (V-6)
Made I No. V-504-C210 (V-8)
Detroit Diesel Engine Division
Model No. 305X (3-71N) (3-IN-LINE)
Model No. 4055C (4-71N) (4-IN-LINE)
MOTOR GENERATOR DIVISfON
HOBART BROTHERS COMPANY
TROY, OHIO 45373
U.S.A.
l-68
022873
INTRODUCTION .,
This manual contains operation, maintenance, adiustment , and trouble shooting information
for an electric-hydraulic governor system used on certain diesel engines. The system is
identified as a Woodward, 2301.
Instructions cover two basic applications of the governor. They apply to installations.on
Cummins, V-6 and V-8 engines, and Detroit Diesel, in-line 3 and 4 cylinder engines.
Any information which applies to only one installation will be qualified and identified
as such.
The manual is not intended to be a text book on electricity or electronics. Its primary
purpose is to provide information and instructions to experienced operators, electricians,
and mechanics who have never seen, operated, or serviced an electric-hydraulic governor.
The manual should be read completely before attempting to operate, adjust, or trouble
shoot the system.
The manual is divided into three chapters. Each chapter is divided into as many sections
as required., Each new section starts with page 1, and illustrations within each section are
identified consecutively from Figure 1 through as many as required. To reference material
to be found in another section, it is referred to by chapter-section, and paragraph or figure
number.
Introduction
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FOBART D : iMOTOR GENERATOR DIVISION D % QD : HOBI\RT BROTHERS COMPANY % Q. Bl++
Introduction Feb 28/73
noBART e a QD
iMOTOR GENERATOR DlVlSlON
“c 2 HOBART BROTHERS CCIMPANY b . B &,d
SUBJECT
Description/Operation
Description
General
TABLE OF CONTENTS
Electric-Hydraulic Governor System Components
Electric Control Unit
Hydraulic Actuator
Magnetic Pickup
Miscel Ianeous Equipment
Operation
General
Starting, Operating, and Stopping the Engine
Servicing
Maintenance
General
Inspection
Lubrication
Periodic Maintenance
Replace Hydraulic Actuator
Remove Actuator
lnstal I Actuator
Replace Electric Control Box
Remove Control Box
CHAPTER/SECT ION PAGE
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Contents
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SUBJECT
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“0 i HOBART BROTHERS COMPANY B . B,7+e
TABLE 0~ CONTENTS (C~NT’D.)
Install Control Box
Replace Magnetic Pickup
Adjustment
General
Contents Feb 28/73
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CHAPTER/SECTION
Actuator Linkage Adjustment
Geneial
Adjust Actuator Linkage on Cummins Engines
Adiust Actuator Linkage on Detroit Diesel Engines
Magnetic Pickup Adjustment
General
Adiustment Procedures
Hydraulic Actuator Adjustment
General
Adjustment Procedures
Electric Control Box Adiustment
General
Adjustment Procedures
Trouble Shooting
Theory of Operation
General
Basic Theory of Operation
Trouble Shooting Procedures
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;MOTOR GENERATOR DIVISION HOBART EmOTHERS COMPANY
TABLE OF CONTENTS (CONT’D.)
SUBJECT CHAPTER/SECTION
General 3-2
Trouble Shooting Chart
Description
Use of Trouble Shooting Chart
Equipment for Trouble Shooting
Safety
Connections and Leads
Trouble Shooting Guides
LIST OF ILLUSTRATIONS
CHAPTER/ FIGURE
SECT ION NUMBER
l-l 1 Electric Control Box (Old Style)
l-l 2 Electric Control Box (New Style “Fail-Safe”)
l-l 3 Hydraui ic Actuator
l-l 4 Magnetic Pickup
2-l 1 Actuator Installation on Cummins Engine
2-l 2 Actuator Installation on Detroit Diesel Engine
2-l 3 Control Box Installation on All Units Except
Self-Propelled
2-l 4 Control Box Installation on Self-Propelled Units
2-l 5 Magnetic Pickup lnstal Iation on Cummins Engines
2-2 1
2-2 2
2-2 3
2-2 4
2-2 5
2-2 6
2-2 7
TITLE
Actuator Linkage, Cummins Engines
Actuator Linkage, Detroit Diesel Engines
Magnetic Pickup
Hydraulic Actuator Adjustment
Actuator Test Circuit
Electric Control Box and Potentiometer (Original,
Old Type)
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Electric Control Box and Potentiometer (New Fail-Safe
TY P”) 10
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Contents
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CHAPTER/ FIGURE
SECTION NUMBER
3-l 1
3-l 2
3-2 1 Electric Governor Voltage Values 3-2 2 Trouble Shooting Chart
HOBART I I QB
iMOTOR GENERATOR DIVISION
“c 2 HOBw?T BRcnHERS CCIMPANY % Q . B ,I+”
LIST OF ILLUSTRATIONS (CONT’D .)
TITLE
Actuator Cross-Section
Speed Setting Potentiometer Schematic
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Contents
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“c 2 HOBART BROTHERS COMPANY
% *. BL,d-
CHAPTER 1. DESCRlPTlON/OPERAT ION
SECTION 1. DESCRIPTION
1. General
The electric-hydraulic governor system is installed on engine-driven generator sets by
Hobart Brothers Company to replace conventional, mechanical type governors. This
system for control of engine speed (and generator output frequency) was selected for
this application because it provides constant speed, and faster engine response to
changes in load conditions, which result in much closer frequency control.
2. Electric-Hydraulic Governor System Components
The governor system consists of the following main components:
Electric control unit with potentiometer
Hydraulic actuator
Magnetic pickup
A. Electric Control Unit (See Figures 1 and 2)
The electric control unit (Fig. 1) is a compact assembly of solid state components
enclosed in a metal box. Two adjustments, “gain” and “reset droop”, are provided
for adiustment of response time and stability. An externally mounted potentiometer
provides adjustment for engine speed. The function of the control unit is to compare
a signal from the speed setting potentiometer to a signal from the speed-sensing
magnetic pickup and as a result of this comparison, to send a signal to the hydraulic
actuator which will cause the actuator to increase, decrease, or hold engine speed
steady as required. A newer, “fail-safe”, control unit (Fig. 2) is now available.
It is somewhat different in appearance in that “gain” and “reset droop” adjustments
are relocated. It is easily recognizable by the absence of a diode connected
between terminals No. 1 and No. 8. The newer control unit has “fail-safe”
capability which means that the engine will not overspeed in case of input signal
(AC magnetic pickup or DC power) failure. Hereafter the electric control unit
will be referred to as the control box.
B. Hydraulic Actuator (See Figure 3)
The function of the hydraulic actuator is to position the engine speed-control lever
as required to maintain a constant engine speed regardless of load conditions. The
output shaft (and lever) of the actuator is mechanically connected through a Iink-
age arrangement to the fuel pump speed-control lever on Cummins engines, and to
the injector rack speed-control lever on Detroit Diesel engines. Hydraulic power
for operation of the actuator is supplied by the engines’ fuel pressure system.
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Electric Control Box (Old Style)
Figure 1
Electric Contml Box (New Style “Fail-Safe”)
Figure 2 t
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“0 2 HOBART BROTHERS COMPANY
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Operation of the actuator is controlled by a 12-V DC signal from the control
bOX.
Hydraulic Actuator
Figure 3
C. Magnetic Pickup (See Figure 4)
The magnetic pickup is a device for detecting the speed of the engine. It is
mounted in the flywheel housing directly over the ring gear. It generates an AC signal when the flywheel teeth pass through the magnetic field at the end of the
pickup. This signal is conducted to the control box through a coaxial cable.
The control box uses the AC signal to electronically determine whether engine
speed should be increased, decreased, or held steady to meet predetermined
speed requirements.
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Magnetic Pickup
Figure 4 t
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D. Miscellaneous Equipment
In addition to main components described above, the system requires a shielded
coaxial cable between the magnetic pickup and control box, governor throttle
linkage, mounting brackets, and other miscellaneous hardware and wiring.
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SECTION 2. OPERAT’ION
1. General
From an operator’s viewpoint, operation of the electric-hydraulic governor is very
simple. To give the governor system full control of engine speed, it is only necessary
to apply 12-V DC to the control box by operating a switch as instructed in the basic
generator set manual.
2. Starting, Operating , and Stopping the Engine
Refer to the Generator Set Manual for all engine operating procedures.
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!jMOTOR GENERATOR DIVISION
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CHAPTER 2. SERVICING
SECTION 1. MAINTENANCE
1. General
To make certain the governor system is ready for operation at al I times, it must be in-
spected and checked systematically, and regularly, so that defects may be discovered
and corrected before they result in failure of the equipment.
2. Inspection
A periodic inspection schedule should be established and maintained. Throttle linkage
should be checked at least every two weeks, or after each 100 hours of operation. ln-
spect for free operation throughout the full travel of the linkage’. Check the security
of all linkage attaching and adiusting hardware.
Check all electrical connections at the control box and at the actuator.
Check tube and hose fittings for leaks.
3. Lubrication
Engine fuel oil supplies sufficient lubrication for the actuator. No additional lubrication
is required.
4. Periodic Maintenance
Other than inspections and checks described above, no periodic maintenance is re-
quired.
5. Replace Hydraulic Actuator
Figure 1 illustrates an actuator installation on a Cummins engine. Figure 2 represents
an installation on a Detroit Diesel engine.
A. Remove Actuator
(1) Observe and mentally note the color and location of wire leads at the actuator.
Disconnect leads and cable shield ground.
(2) Disconnect input fuel oil tube and drain hose.
(3) Disconnect governor rod from actuator lever at ball-joint.
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Actuator Installation on Cummins Engine
Figure 1
Actuator Installation on Detroit Diesel Engine
Figure 2
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;MOTOR GENERATOR DlVlSiON
“c 2 HOBART BROTHERS COMPANY % Q. B,+e’
(4) Remove two actuator mounting screws and lift off the actuator.
B. Instal I Actuator
(1) Position actuator on mounting bracket and align mounting holes. Install
mounting screws and tighten securely.
(2) Attach governor rod ball-ioint to actuator lever. Actuate linkage to check
for free operation.
(3) Connect input tube and drain hose.
(4) Connect leads at input terminals. Ground the cable shielding with an actuator
cover screw.
NOTE: Check Generator Set connection or schematic diagrams if
necessary to be certain of correct wiring.
(5) If actuator lever was removed or disturbed, check and adjust governor linkage
in accordance with Sect. 2-2, Para. 2, B, or C.
6. Replace Electric Control Box
The electric control.box is mounted on a vertical panel which is attached to the lifting
frame on al I units except the self-propel led type machines (see Fig. 3).
On self-propelled units the electric control box is mounted on the floor of the main
control box behind the instrument panel (see Fig. 4).
NOTE: On ail current “B” Specifications the electric control box is mounted
on the rear panel of the main control box.
A. Remove Control Box
(1) ldentify six input and output leads and carefully disconnect (see 2-2, Figs.
5 and 6). Leave reverse polarity diode and potentiometer leads attached (if
so equipped).
(2) Disconnect grounded shielding. Remove box attaching hardware and remove
box. Do not loose rubber mounts.
8. Install Control Box
(1) Carefully position box on rubber mounts and install attaching hardware.
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Control Box Installation on All Units Except
Self-Propelled
Figure 3
Contml Box Installation on Self-Pope Figure 4
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4? 9. B,7G- (2) Ground the cable shielding and make certain ground lead is properly grounded.
(3) Reconnect all input and output leads. Refer to Sect. 2-2, Fig. 5 or 6, if
necessary for correct wiring.
C. Replace Magnetic Pickup
The magnetic pickup requires critical adjustment when replaced. Refer to Sect.
2-2, Para. 3, B for replacement and adiustment instructions.
See Fig. 5 for magnetic pickup installation on Cummins engines. Installation on
Detroit Diesel engine is shown in Sect. 2-2, Fig. 3.
Magnetic Pickup Installation on Cummins Engines
Figure 5 t
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SECTION 2. ADJUSTMENT
1. General
All of the electric-hydraulic governor system main components, namely the magnetic
pickup, hydraulic actuator, and electric control box, have critical adjustments which
can affect engine performance and therefore, generator output. Actuator-to-fuel con-
trol lever adiustment can also affect engine performance.
When the complete system is to be checked, and/or adjusted, a definite sequence of
procedures should be followed:
First - Check or adiust actuator linkage
Second - Check or adjust magnetic pickup
Third - Check or adjust actuator
Fourth - Check or adjust electric control box
2. Actuator Linkage Adiustment
A. General
The proper adiustment of the mechanical linkage between the hydraulic actuator
and engine speed-control lever is important to the satisfactory operation of other
electric-hydraulic governor components.
One of the most important things to remember about linkage adjustment is that the
actuator and linkage must move the speed control lever through its complete range
of travel, from full idle position to full speed position. An adiustment which does
not provide full travel can cause sluggish operation and poor response time under
load. Also remember to use as much of the actuator lever travel as possible. The
actuator output lever has a maximum travel range of 30 degrees.
B. Adjust Actuator Linkage on Cummins Engines (See Fig. 1)
When adjusting linkage on Cummins engines, remember that the combined weight
of levers (4 and 8, Fig. 1) and rod assembly (7) will automatically hold the linkage
in FULL-SPEED position when the engine is stopped. Check and adjust linkage as
fo I lows:
(1) Assuming that linkage is connected, disconnect and remove rod (7) assembly
by disconnecting ball-ioints (5 and 10) from levers (4 and 8).
(2) Check adjustment and positioning of fuel pump speed control lever (8). The
lever should be positioned on the shaft (9) so that it is pointing toward the
rear of the engine at an angle of about 10 degrees below horizontal when
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z : QQ iMOTOR GENERATOR DIVISION
“c 5 HOBART BROTHERS COMPANY
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the pump shaft (9) is rotated as far as it will go counterclockwise to FULL-SPEED
position (see Fig. 1). Loosen lever clamping screw and reposition lever as re-
quired. Tighten clamping screw securely. Actuate lever to be certain it does not touch any engine parts throughout its full travel range.
(3) Measure the length of rod (7) between adiusting nuts (6). Correct length is
5-l/16 inches. If length, is not within l/16 inch of this dimension, loosen
nuts (6) and adjust.
(4) Connect ball-joint (10) to pump-lever (8) in the threaded hole nearest the ’
end. With both levers (4 and 8) in FULL SPEED position, attempt to connect
the rod assembly to actuator lever (4) in the second mounting hole from the end.
If joint (5) attaching screw will thread easily into the mounting hole the
actuator lever (4), it is properly adjusted on the actuator output shaft (2). If joint screw does not line-up with the mounting hole; loosen clamping bolt
in lever (4) and reposition lever. When repositioning the lever, be sure the
shaft (2) is held in its full speed position (full clockwise rotation). Tighten
lever clamping bolt, and connect rod assembly to lever (4) by installing ball-
joint (5) mounting screw in second mounting hole from end of lever.
REAR FRO NT
View from right
side of engine
(shown in FULL SPEED position)
1. Actuator 6. Nut
2. Actuator output shaft 7. Rod
3. 12-V input terminals 8. Fuel pump lever
4. Actuator lever 9. Fuel pump shaft
5. Ball-joint 10. Ball-joint
2-2
Actuator Linkage, Cummins Engines
Figure 1 s 1’
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HOBART BROTHERS COMPANY
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(5) Actuate linkage throughout its entire range. Be sure action is free, and with-
out binding or interference. 6
C. Adjust Actuator Linkage on Detroit Diesel Engines (see Fig. 2)
When the engine is stopped, this linkage is normally in IDLE SPEED position. Check
and adjust I inkage.
(1) Disconnect ball joint (2, Fig. 2) from actuator lever (1).
(2) A spring in the speed limiting governor will hold the speed-control lever (5)
in full IDLE position. In this position it should point almost straight outward
at an angle of approximately 10 degrees toward the rear of the engine.
(3)
(4
(5) Move lever (1) to FULL SPEED position (toward the radiator) and make certain
that the linkage will operate the speed control lever freely throughout its full
travel from IDLE to FULL SPEED positions.
(6) Be sure all linkage attaching parts are securely tightened.
Move the actuator lever (1) toward the rear of the engine. In full IDLE position
it should be pointing almost straight upward at an angle of about 10 degrees
toward the rear of the engine (see Fig. 2). If lever (1) requires adjustment,
loosen the lever clamping screw. Rotate the actuator output shaft (12) in a
clockwise direction to full IDLE position and reposition the lever (1) as required.
Tighten lever clamping screw.
With speed control lever (5) and actuator lever (1) both in full IDLE position,
attempt to connect ball joint (2) to lever (1). If ball joint mounting screw
and threaded mounting hole in the lever do not line-up, loosen nuts (7) and
adjust length of rod (4) so that the ball joint may be attached to lever (1)
when both levers are in full IDLE position.
3. Magnetic Pickup Adjustment
A. General
The strength of the magnetic pickup signal to the control box can be weakened if
the tip of the pickup is too far from the flywheel ring gear. If the pickup is to be
removed for any reason, or if the signal is weak, as indicated by test (see 3-2,
Fig. l), the pickup must be adjusted-.
B. Adjustment Procedures
Magnetic pickup adiustment procedures are the same for all installations. Refer
to Fig. 3.
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REAR
Viewed from left
side of engine
1. Actuator lever 2. Ball joint
3. Fuel shut-off lever
4. Rod
5. Speed control lever
6. Ball joint
7. Locknuts
8. Fuel pressure line
9. Terminal
10. Terminal
11. Actuator
12. Actuator output shaft
Actuator Linkage, Detroit Diesel Engines
Figure 2
(1) Disconnect “Amphenol” connector (1, Fig. 3).
(2) Loosen nut (3) and remove magnetic pickup (2).
(3) Inspect to make certain the tip is not damaged from contact with the ring
gear teeth (replace pickup if damaged).
(4) Rotate the engine as required to locate a ring gear tooth directly below the
tapped, pickup mounting hole. An i,maginary line should pass through the center of the mounting hole, the center of a flywheel tooth and the center
of the flywheel.
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roBART E a QQ iMOTOR GENERATOR DlVlSlON
“0 2 HOBART BROTHERS COMPANY
b. BL,I++
Install the magnetic pickup and thread into the mounting hole until the tip
touches the “in line” flywheel-gear tooth . .
CAUTION: THE PICKUP TIP MUST BE DIRECTLY OVER A TOOTH AND
NOT BETWEENTEETH WHEN ADJUSTMENT IS MADE.
Back the pickup outward (counterclockwise) l/2 turn. Hold the pickup securely
in this position and tighten nut (3). This adjustment will result in a clearance
of approximately 0.028 inch between the pickup tip and the flywheel teeth and
give an operating AC voltage of 4 V to 8 V at the control box terminals 5 and
6, when the engine is running at no load and governed speed.
Connect “Amphenol” connector (1).
-.
. “.
1. Connector
2. Magnetic pickup
3. Nut
Magnetic Pickup
Figure 3 t
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:MOTOR GENERATOR DlVlSlON
“0 i HOBART BROTHERS COMPANY
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4. Hydraulic Actuator Adjustment
A. General
This operation is designed to confine all testing and adiusting to the actuator alone,
and to eliminate the influence of any governor problems outside the actuator. The
operation actually becomes a simulated bench test.
The actuator has one adiustment which determines the voltage values required to
correctly position the output shaft (and lever) throughout its operating range. This
adjustment is controlled by an adiusting screw (3, Fig. 4) located in the bottom
of the actuator body.
8. Adjustment Procedures
To test and adiust the actuator on the engine, proceed as follows:
(1) Start engine and operate at idle speed. With engine-generator controls in IDLE
position, the actuator will be receiving NO signal from the control box.
(2) Note position of actuator leads (black and white) at terminals (1 and 2, Figure
4) so that they may be reconnected properly; then disconnect.
(3) Disconnect ball-joint and rod assembly from actuator lever (see Fig. 1 or 2).
CAUTION: SECURE ENGINE SPEED CONTROL LEVER IN IDLE POSITION.
(4) Make certain the hydraulic pressure (fuel oil) supply to the actuator is adequate
and clean.
NOTE: A restrictor fitting is used in the pressure supply line to the actuator
on all Cummins engines. This fitting is located on the fuel pump
pulsation damper.
(5) Connect a test circuit to actuator as illustrated in Fig. 5. Actuator output
shaft (and lever) should move through its range as potentiometer knob is rotated
and should ,take a given position for each potentiometer setting.
NOTE: If output shaft operates erratically, the trouble is in the hydraulic
supply or the actuator.
(6) Set potentiometer of test circuit so that 1 .5 * 0.2 V DC is supplied to input
terminals of actuator. The actuator shaft and lever should just move off minimum
fuel (idle) position at this voltage. If shaft has not moved off minimum, loosen
locknut (4, Fig. 4) and turn adiusting screw (3) OUT until output shaft does
just leave minimum position. Tighten locknut. .
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iMOTOR GENERATOR DIVISION
“0 P HOBART BROTHERS COMPANY
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1. Dxitive terminal 4. Locknut
2. Negative terminal 5. Pilot valve bushing
3. Pdiusting screw 6. Actuator
Hydraulic Actuator Adiustment
Figure 4
-I- .. 25 OHh’l
12 V.D-C
SUPPLY
POTENTIOMETER POTENTIOMETER
c c
TO ACTUATOR TO ACTUATOR
TERK’INALS TERK’INALS
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Actuator Test Circuit
Figure 5 t
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P f QQ
EMOTOR GENERATOR DIVISION 2
“0 z HOBART BROTHERS COMPANY
% Q. ah77 ‘Q+
NOTE: (a) Use a 5/32-inch Allen wrench to turn the socket-head adjusting
screw (3).
(b) Prevent the actuator pilot valve bushing (5) from turning while
loosening or tightening nut (4), or adjusting screw (3), by placing
an open-end wrench across flats on the bushing.
If at the above input voltage the output shaft has rotated more than 5 degrees
off minimum position, loosen locknut and turn adjusting screw IN until output
shaft moves to just off minimum fuel position. Tighten locknut.
(7) Disconnect test circuit and connect actuator input leads.
(8) Reconnect actuator linkage.
(9) To test, operate the engine at normal governed speed (400 Hz, indicated on
frequency meter). Connect a voltmeter to actuator input terminals (1 and 2,
Fig. 4). If the actuator and linkage are properly adiusted, the voltmeter
should indicate a voltage of 2-V to 4-V DC on the 12-V DC scale.
5. Electric Control Box Adiustment
A. General
Before making an’ adjustment to the control box, make certain the linkage between
the actuator and fuel control lever is free and that there is no backlash, “play”, or
lost mot ion in the linkage. Be sure the magnetic pickup is producing a strong, normal
output. Be sure adequate fuel oil pressure is reaching the actuator and that the
actuator is properly adjusted. The actuator servo piston must be free and not stick-
ing. Adjust control box 8s follows:
B. Adiustment Procedures
(1) Start engine and allow it to warm.
(2) Accelerate engine to governed speed. (See Generator Set Manual .)
(3) Use the adjusting screw in the speed-setting potentiometer (Fig. 6 or 7) to
adjust engine speed to produce a generator output of exactly 400 Hz.
NOTE: (a) A very small screwdriver is required for this adjustment. Turn the
screw CLOCKWISE to INCREASE engine speed, and COUNTER-
CLOCKWISE to DECREASE speed.
(b) This is a 24-turn potentiometer with no stops. The adjusting screw
is designed to slip when the wiper reaches the end of its travel
in either direction. t
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FOBART % t QQ ;MOTOR GENERATOR DlVlSlON
“0 ,: HOBART BROTHERS COMPANY
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To 12-v DC! SolEce
Speed Adjusting' Potentiometer
Reverse Pohr
Electric Control Box and Potentiometer (Original, Old Type) Figure 6 t
2-2
Page 9
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rOBART D s 0 “0 QQ
iMOTOR GENERATOR DIVISION * 2 HOBRAT BROiHERS COMPANY
a . B @+
0 <. ,O
I HORA RT BROTHERS NO. 389870 I
C.W. - Increase
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TO TO
Hydraulic. Actuator r Magnetic Pickup
Shielding Ground
C.C.W. - Decrease
2-2
Page 10
Electric Control Box and Potentiometer (New Fail-Safe Type)
Figure 7 t
Feb 28/73
a. _- -_s .f
FOBART
I a QQ
EMOTOR GENERATOR DIVISION
“c 2 HOBART BROTHERS COMPANY
% Q. @LO 6
(4) With the engine running smoothly at governed speed (400 Hz), manually force
the actuator lever to an “under-speed” position momentarily to simulate a
sudden loaded condition. The actuator should act immediately to bring the
engine up to governed speed without surging. If actuator action is slow or if
surging is present, adjust the “gain” and “reset-droop” potentiometers per
steps (5) and (6).
(5) Loosen locknuts on “gain” and “reset ‘droop” adjusting screws. Set both adjust-
ing screws at midrange (no. 5 on the scale). Turn the “gain” adjusting screw
slowly clockwise until engine operation becomes slightly unstable (surges).
NOTE: It may be necessary to manually force the actuator lever to an
underspeed position momentarily to initiate surging.
(6) -Adjust “reset-droop” to stabilize engine speed. (Screw rotation requirement,
CLOCKWISE or COUNTERCLOCKWISE, cannot be predetermined .) Again,
turn the “gain”
unstable.
adiustment screw CLOCKWISE until the engine becomes slightly
Stabilize with “reset” adjustment. Repeat steps (5) and (6) until the
reset potentiometer will no longer stabilize engine operation. Turn the gain
adiusting screw back to its last position and stabilize.
NOTE: Although best performance is obtained with the “gain” setting as high
as possible (clockwise) while the engine is still stable, it is not ad-
visable to adjust the “gain” too high because an excessively “high”
or-delicate adiustment will very likely result in unstable (surging)
operation when the unit is not thoroughly warmed. Adiust gain and
reset droop to maximum while still attaining stability. Then back
off both settings by 2 digits. For example, scale settings of 8 and 6
should be backed off to 6 and 4.
(7) Tighten locknuts when adjustment is completed.
t
Feb 28/73 7’
2-2
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Feb 28/73 ,-- I/ -,. i' z .:- _
HOBART e 5
QD
$MOTOR GENERATOR DIVISION
> i HOBART EROTHEAS COMPANY 9 4. BLTt5+
1. General
2.
CHAPTER 3. TROUBLE SHOOTING
SECTION 1. T.HEORY OF OPERATION
The electric-hydraulic governor system is primarily an electrical installation. The only
-hydraulic function performed is actuation of the mechanical fuel control linkage through
a piston and lever arrangement in the actuator. Engine fuel pressure supplies the re-
quired hydraulic power.
The system consists of four principal components which are illustrated schematically on
diagrams which accompany the Generator Set Manual. Components are identified on
schematics as: “electric governor control box”, “magnetic pickup”, “actuator”, and
“2RH” which is the speed setting potentiometer.
The electronic circuitry of the control box will not, and need not, ‘be discussed in the
theory of operation. Operators and, maintenance .personnel should concern themselves
only with signals which enter and leave the contrdl box. Servicewise the control box
should be considered as an adjustable and replaceable module and should be serviced as
such.
Basic Theory of Operation
Electrical operating power is supplied to the control box from the 12-V DC engine system
through variqus switching and relay circuits depending upon the end item (self-propelled,
tractor mounted, etc.) requirements. Input power (12-V DC) enters the box through
terminal No. 1, however on some of the original old style boxes it is routed by way of
terminal No. 8, which is not internally connected. This method is used mainly to pto-
vide convenient mounting and connection for a diode (4REC), which is used to prevent
accidental entrance of reverse polarity into the solid state circuitry of the control box.
New type “fail-safe” control boxes are equipped with an internally mounted diode,
therefore input power is connected directly’ to terminal No. 1 on these boxes. The con-
trol box receives two signals; one from the potentiometer (2RH), and one from the MAG-
NETIC PICKUP. The control box sends a signal to the ACTUATOR.
The voltage value of the input signal from the potentiometer (2RH) determines the
governed speed of the engine. The potentiometer signal enters the box through terminals
9 (+) and 10 (-) . Th e value of this signal may be varied from 0 V DC (minimum engine
speed) to 1.5 V DC ( maximum engine speed). Voltage (and engine speed) is increased
by turning the “pot” adjusting screw CLOCKWISE. It is decreased by turning the screw
COUNTERCLOCKWISE (Ref. Sect. 2-2; Figs. 6 and 7). Twenty-four complete turns
(revolutions) of the screw are required to move the adiusting slide from minimum to
maxiumum speed setting. There are no stops, as such, on this potentiometer; however
the adjusting screw will “slip” to prevent damage to internal parts when the slide reaches
Feb 28/73 x..._ J j I:.+~ rnL ‘ _,
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HOBART
e z
QD
;MOTOR GENERATOR DIVISION
“c 2 HOBART BROTHERS COMPANY %. &..,l@+
either end of its travel. In schematic diagram (Figure 2) the potentiometer adiusting
slide is shown in maximum voltage (and speed) position. The potentiometer signal is
amplified after it enters the control box and becomes the speed setting signal voltage.
The other signal which enters the control box is an AC signal from the magnetic pickup,
which is a device for sensing the speed of the engine. The pickup is mounted in the
flywheel housing, with the tip (magnetic field end) very close to the starter ring gear.
The device will produce a voltage output when any magnetic material moves through
its. magnetic fie Id. Thus, as each tooth on the ring gear passes through the magnetic
field, an electric pulse is sent to the control box.
Inside the box these pulses are converted to DC voltage proportional to engine speed.
An increase in engine speed results in an increased voltage, and conversely a decrease
in engine speed results in a decrease in voltage. The DC voltage converted from the
pulsing signal out of the magnetic pickup becomes the speed signal in the control box.
In operation, the speed signal voltage is compared to the speed setting signal voltage
as adjusted by the potentiometer (2RH). The difference between these signals deter-
mines the value of the output signal voltage to the actuator.
The hydraulic actuator is a proportional type, that is, its output shaft takes an angular
position proportional to a given input signal voltage. As stated above, the actuator is
electrically controlled and is hydraulically powered by fuel oil pressure. It has no
rev0 lving parts. (See Figure 1.) A pilot valve controls flow of oil to (or from) a servo
piston which is connected by an internal lever to an output shaft. Actuator power is
transmitted from the actuator output shaft to the engine speed control arm through a
lever and adjustable rod mechanism. As the pilot valve moves downward, oil is admitted
under the servo piston to push it up and increase engine speed. When the pilot valve
moves upward, oil is released from beneath the piston, allowing it to move downward
and reduce engine speed.
The actuator pilot valve is attached to a permanent magnet in a transducer. The output
signal from the control box passes through the transducer coil and tends to push the mag-
net and pilot valve plunger downward. A feedback spring and a top centering spring add
to this downward force. A bottom centering spring resists the downward push. When the
engine is running “on speed”, these opposing forces are equal and the pilot valve is
centered so that no oil flows to, or from, the actuator servo to change the position of
the output shaft. A change in the voltage signal from the control box results in a
change in the pilot valve position. The resulting oil flow to (or from) the servo pro-
duces a change in the output shaft to either increase or decrease engine speed. For
each input signal voltage from the control box, there is but one position of the output
shaft at which the bottom centering spring force exactly opposes the force in the trans-
ducer coil and the top springs when the pilot valve is centered.
3-l
Page 2
Feb 28/73
GENERATOR DIVISION nOBART BROTHERS COMPANY
Feedbtlck-" Spring
1 h \ \ \
El.01 Valve 3~ shing,
Actuator Goss-Section
Figure 1 I
Feb 28/73 -‘=y _)\ L ‘_ ;,*x c
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!OBART D a QD
iMOTOR GENERATOR DIVISION
% 2 HOBART BROTHERS COMPANY
‘CF 0. BL&
During an underspeed condition, when engine speed is below the speed selected by the
potentiometer, the control box output voltage to the actuator is at maximum (as high as
8 to 10 V DC), to force the magnet and pilot valve down and allow the actuator piston
and output shaft to move to maximum fuel position. During an overspeed cord ition
when engine speed exceeds the set speed, the control box output voltage will be zero
and the actuator will move to minimum fuel position.
At no-load, the governor will control engine speed with a control boxoutput (actuator
input) of 2 V to 4 V DC. At full load, the voltage will be 0.5 V to 1 .O V DC higher
than no load value. Response time and stability of the system are adjustable by two
potentiometers identified as “GAIN” and “RESET-DROOP” controls on the electric
control box (Sect. 2-2, Figs. 5 and 6). Adjustment of these controls is covered in
Section 2-2, Para. 5, B, (5) and (6). Electric governor voltage values are contained
in Section 3-2, Fig. 1.
/-
ELECTRIC
CO NTRO L BOX
TERMINALS
SLIDE DIRECTION - ADJUSTING SCREW ROTATION
SLIDE SHOWN AT - CW - INCREASE VOLTAGE
MAXIMUM VOLTAGE AND ENGINE SPEED.
AND ENGINE SPEED
POSITION - CCW - DECREASE VOLTAGE
AND ENGINE SPEED.
/
.
Speed Setting Potentiometer Schematic
Figure 2
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Feb 28/73
II” I:: i
HOBART z 6 QD
$MOTOR GENERATOR DIVISION
“0 i HOBART BROTHERS COMPANY
% 4. B,+e
.
SECTION 2. TROUBLE SHOOTING PROCEDURES
1. General
Trouble shooting is an orderly process of checking and eliminating possible causes of
trouble until the exact cause of a trouble is found. As a rule, the best place to start
looking for the cause of a trouble in a circuit is at the source of power. Continue test-
ing and checking the circuit, step-by-step, in an orderly manner, until the cause of
trouble is located. See applicable connection diagrams and schematic diagrams which
are furnished with the generator set or governor “kit”.
2. Trouble Shooting Chart
A. Description
The trouble shooting charts lists information under three headings:
(1) Trouble, symptom, and condition
(2) Probable cause
(3) Test, check, and remedy
B. Use of the Trouble Shooting Chart
Read the trouble symptoms and conditions before proceeding to causes and remedies.
For example, at the beginning of the trouble shooting chart, the first trouble listed
is: “Engine will not come up to governed speed”. If the engine does come up to
speed, then obviously this is not your symptom and condition. Proceed to the next
trouble and symptom directly below. When the applicable trouble symptom and
condition has been found, look to the right under PROBABLE CAUSE and TEST,
CHECK, AND REMEDY to find the various things which could cause the trouble
and what to do to check and correct them.
3. Equipment for Trouble Shooting
A good quality multi-scale voltohmmeter is the only instrument required for trouble
shooting. At least two “jumper” leads with “alligator”, or similar clips, may be
required. The 12-V, engine electrical system is used for the 12-V DC power source.
4. Safety
WARNING: EXERCISE EXTREME CARE TO AVOID CONTACT WITH HIGH VOLTAGE
LEADS AND COMPONENTS WHICH COULD CAUSE SERIOUS SHOCK
AND INJURY IF TOUCHED WHEN TROUBLE SHOOTING OR OPERAT-
ING ANY EQUIPMENT.
I
Feb 28/73 .-,- .[_ -~(,‘g
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Page 1
HOBART
: t
QD
iMOTOR GENERATOR DIVISION
,= HOBART BROTHERS COMPANY “c 5 . B ,+*
5. Connections and Leads
ALWAYS make a check of connections and leads to a component suspected of being
faulty. With the exception of a few instances, we wil I assume that connections and
wiring have always been checked first and that power has not been lost as a result of
defective wiring or connections.
6. Trouble Shooting Guides
The following facts concerning the operation of the electric-hydraulic governor may be
helpful in understanding the system and in determining which unit in the system is
faulty in case of troubles.
A. The system requires three sources of power to operate normally.
(1) 12-V DC input power (from engine circuit).
(2) Approximately 4-V to 6-V AC input power (from magnetic pickup).
(3) 20 psi, or more, pressure (from engine fuel oil system).
NOTE: Low pressure will result in sluggish actuator operation.
B. Assuming other conditions are normal, the actuator will go to, or remain in,
CLOSED THROTTLE position under the following conditions:
(1) No 12-V DC po wer from engine electrical system.
(2) No voltage from control box to actuator.
C. Also assuming other conditions are normal, the actuator will go to FULL THROTTLE
position under the following condition:
(1) No signal (AC po wer ) f tom the magnetic pickup to the control box. (Applies
to all boxes except “fail-safe” (see 2-2, Fig. 7.)
D. The actuator will “surge” or “hunt” under the following conditions:
(1) “Rate” or “gain” potentiometers improperly adjusted.
(2) Actuator linkage to governor throttle,. loose.
(3) Throttle linkage binding.
(4) bw fuel pressure at actuator.
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FOBART D ii gMOTOR GENERATOR DIVISION n “c
QD d HOBART BROTHERS COMPANY
% Q.BLO ‘+
(5) Dirty actuator.
(6) Weak signal from magnetic pickup.
E. Electric governor voltage values are listed in Figure 1.
-
L
Terminal #8 (Input, anytime switch is ON) (approx.)
Terminal #9 (apptox.) to -
Terminals #9 to #lo (approx.)
Terminals #3 to #4 (on speed, no load)
(Input’to actuator)
Terminals #3 to #4 (on speed, full load)
12. V DC
8. to 10. V DC
1.5 V DC
2. to 4. V DC
0.5Vto l.OVDC
HIGHER than NO
LOAD value.
Terminals #5 to #6 (Magnetic pickup input
at box; leads connected, idle speed)
NOTE: 1. Some early production boxes have an input
rating of 0.5 V AC minimum.
2. V AC minimum
2. Values will increase with increased engine speed.
Magnetic pickup output. (Leads disconnected from
box. All models. Idle speed.) 6. V AC minimum
WARNING: NEVER DISCONNECT MAGNETIC PICKUP LEADS WHEN THE
ENGINE IS RUNNING AT GOVERNED SPEED.
Feb 28/73 .“.-e. ~.’ .>, .A / 1‘
Electric Governor Voltage Values
Figure 1
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YOBARI
t QD EMOTOR GENERATOR DIVISION
z : HOBART BROTHERS COMPANY “0 e b . B ,, I++
‘ROUBLE,SYMPTOM,
4ND CO ND IT IONS PROBABLE CAUSE TEST, CHECK, AND/OR REMEDY
! . Engine overspeeds B. Actuator linkage binding B. Check linkage and adjust as re-
(Continued) or improperly adjusted. quired.
C. Defective or sticking C. Clean or replace as required.
actuator.
3. Engine “surges” . A. Actuator linkage loose, A. Check and adjust linkage in
or binding. accordance with Sect. 2-2; Para.
2, Bor C.
B. Electric control box im- B. Adiust in accordance with Sect.
properly adjusted. 2-2; Para. 5, B.
Feb 28/73
1 -(’ ,-- <
Trouble Shooting Chart (Sheet 2 of 2)
Figure 2 3-2
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HOBART 8 z QQ EMOTOR GENERATOR DIVISION
5 “0 2
HOBART BROTHERS COMPANY
% *. BLTl B
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