Woodward UG-5.7 Dial User manual

Installation and Operation Manual
UG Dial Governor
UG-5.7/UG-8/UG-10 Dial
Manual 03040 (Revision E)

DEFINITIONS
This is the safety alert symbol. It is used to alert you to potential personal
injury hazards. Obey all safety messages that follow this symbol to avoid
possible injury or death.
DANGER—Indicates a hazardous situation which, if not avoided, will result in death
or serious injury.
WARNING—Indicates a hazardous situation which, if not avoided, could result in
death or serious injury.
CAUTION—Indicates a hazardous situation which, if not avoided, could result in
minor or moderate injury.
NOTICE—Indicates a hazard that could result in property damage only (including
damage to the control).
IMPORTANT—Designates an operating tip or maintenance suggestion.
The engine, turbine, or other type of prime mover should be equipped with an
overspeed shutdown device to protect against runaway or damage to the prime
mover with possible personal injury, loss of life, or property damage.
The overspeed shutdown device must be totally independent of the prime mover
control system. An overtemperature or overpressure shutdown device may also
be needed for safety, as appropriate.
Read this entire manual and all other publications pertaining to the work to be performed before
installing, operating, or servicing this equipment. Practice all plant and safety instructions and
precautions. Failure to follow instructions can cause personal injury and/or property damage.
This publication may have been revised or updated since this copy was produced. To verify that
you have the latest revision, be sure to check the Woodward website:
www.woodward.com/pubs/current.pdf
The revision level is shown at the bottom of the front cover after the publication number. The latest
version of most publications is available at:
www.woodward.com/publications
If your publication is not there, please contact your customer service representative to get the
latest copy.
Any unauthorized modifications to or use of this equipment outside its specified mechanical,
electrical, or other operating limits may cause personal injury and/or property damage, including
damage to the equipment. Any such unauthorized modifications: (i) constitute "misuse" and/or
"negligence" within the meaning of the product warranty thereby excluding warranty coverage
for any resulting damage, and (ii) invalidate product certifications or listings.
To prevent damage to a control system that uses an alternator or batter
y
-charging
device, make sure the charging device is turned off before disconnecting the battery
from the system.
To prevent damage to electronic components caused by improper handling, read
and observe the precautions in Woodward manual 82715, Guide for Handling and
Protection of Electronic Controls, Printed Circuit Boards, and Modules.
Revisions—Text changes are indicated by a black line alongside the text.
Woodward Governor Company reserves the right to update any portion of this publication at any time. Information
provided by Woodward Governor Company is believed to be correct and reliable. However, no responsibility is assumed
by Woodward Governor Company unless otherwise expressly undertaken.
© Woodward 1982
All Rights Reserved

Manual 03040 UG Dial Governor
Woodward i
Contents
CHAPTER 1. GENERAL INFORMATION...........................................................1
Introduction.............................................................................................................1
Description..............................................................................................................1
References .............................................................................................................2
CHAPTER 2. INSTALLATION PROCEDURES....................................................4
Introduction.............................................................................................................4
Receiving................................................................................................................4
Storage...................................................................................................................4
Mounting Requirements .........................................................................................4
Linkage Attachments..............................................................................................5
Oil Supply ...............................................................................................................7
CHAPTER 3. PRINCIPLES OF OPERATION ...................................................10
Introduction...........................................................................................................10
Component Description........................................................................................10
Operation of the UG Dial Governor......................................................................15
CHAPTER 4. GOVERNOR OPERATION AND ADJUSTMENTS ..........................18
Introduction...........................................................................................................18
Initial Operation for a New Governor....................................................................18
Adjustments..........................................................................................................18
Compensation Adjustments..................................................................................18
Initial Operation for a Repaired or Reassembled Governor.................................20
Test Procedures...................................................................................................22
Test Completion ...................................................................................................25
CHAPTER 5. TROUBLESHOOTING...............................................................26
Introduction...........................................................................................................26
Troubleshooting....................................................................................................26
Definitions.............................................................................................................27
Preliminary Inspection..........................................................................................27
Additional Information for Steam Turbines, Gas and Gasoline Engines..............31
Governor Field Repairs ........................................................................................32
Removal of Governor from Engine.......................................................................32
CHAPTER 6. REPLACEMENT PARTS ...........................................................35
Replacement Parts Information............................................................................35
CHAPTER 7. AUXILIARY EQUIPMENT ..........................................................46
Introduction...........................................................................................................46
Synchronizer Motor and Solenoid Shutdown.......................................................46
PM Synchronizer Motor with Housing..................................................................48
Low Lube Oil Pressure Shutdown........................................................................49
Magnetic Speed Pickup........................................................................................49
Micro Switches and Wiring Harness.....................................................................50
CHAPTER 8. SERVICE OPTIONS .................................................................51
Product Service Options.......................................................................................51
Woodward Factory Servicing Options..................................................................52
Returning Equipment for Repair...........................................................................53
Replacement Parts...............................................................................................53
Engineering Services............................................................................................54
How to Contact Woodward...................................................................................54
Technical Assistance............................................................................................55

UG Dial Governor Manual 03040
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Illustrations and Tables
Figure 1-1. UG-8 Dial Governor ............................................................................iv
Figure 1-2. Recommended Output Shaft Travel Adjustment.................................2
Figure 1-3. UG Dial Governor Outline Drawing......................................................3
Figure 2-1. Linkage Arrangement (for non-linear fuel systems).............................6
Figure 3-1. UG Dial Governor Schematic Diagram..............................................12
Figure 4-1. Maximum/Minimum Speed Stop Adjustment on the Governor..........23
Figure 5-1. Common Bench Tools........................................................................33
Figure 5-2. Normal Field Repair Tools .................................................................34
Figure 6-1a. Parts Illustration for the UG Dial Governor ......................................37
Figure 6-1b. Parts Illustration for the UG Dial Governor ......................................39
Figure 6-1c. Parts Illustration for the UG Dial Governor.......................................41
Figure 6-1d. Parts Illustration for the UG Dial Governor ......................................43
Figure 6-1e. Parts Illustration for the UG Dial Governor ......................................45
Figure 7-1. UG Cover with Bodine Motor and Shutdown Solenoid......................46
Figure 7-2. Installing Cover with Bodine Synchronizer Motor..............................47
Figure 7-3. UG-8 Dial Governor Equipped with Bodine Synchronizer Motor.......47
Figure 7-4. Top View of Weatherproof Housing with PM Synchronizer Motor and
Shutdown Solenoid..........................................................................48
Figure 7-5. UG-8 Governor with PM Motor, Shutdown Weatherproof Housing...48
Figure 7-6. Low Lube Oil Pressure Shutdown......................................................49
Figure 7-7. Magnetic Speed Pickup .....................................................................49
Figure 7-8. Micro Switches and Wiring.................................................................50
Figure 7-9. Wiring Harness on Cover...................................................................50
Table 2-1. Oil Chart................................................................................................8
Table 2-2. Viscosity Comparisons..........................................................................8
Table 4-1. Test Stand Tools.................................................................................21
Table 5-1. Troubleshooting Chart.........................................................................28
Table 5-2. Governor Output Shaft Travel vs Butterfly Valve Travel.....................32
Table 5-3. List of Common Bench Tools..............................................................33
Table 5-4. List of Normal Field Repair Tools........................................................34

Manual 03040 UG Dial Governor
Woodward iii

UG Dial Governor Manual 03040
iv Woodward
Figure 1-1. UG-8 Dial Governor

Manual 03040 UG Dial Governor
Woodward 1
Chapter 1.
General Information
Introduction
The UG Dial governor is available in three different work outputs:
UG-5.7—7.1 Nm (5.2 lb-ft)
UG-8—13.2 Nm (9.7 lb-ft)
UG-10—15.9 Nm (11.7 lb-ft)
The UG-5.7 and UG-8 both use 827 kPa (120 psi) oil pressure, and the UG-10
uses 1034 kPa (150 psi).
Basic operation, adjustment, troubleshooting, and replacement of parts are
similar for the UG-5.7, UG-8, and UG-10.
Description
The UG is a mechanical-hydraulic governor for controlling diesel, gas, or dual
fuel engines, or steam turbines. The UG is mechanically linked to the fuel racks
or to the fuel valves, depending on the system.
The maximum travel of the output (terminal) shaft is 42°.The recommended
travel of the output shaft is 28° from no load to full load, which allows sufficient
overtravel at each end so that the governor can shut down the prime mover and
also give maximum fuel when required. See Figure 1-2 for recommended output
shaft travel adjustment.
Normally, the UG operates isochronously (constant speed) regardless of load on
the engine, except as described in Chapter 3, Principles of Operation.
Speed droop is incorporated in the UG Dial governor to divide and balance load
between units driving the same shaft or paralleled in an electrical system.
A load limit control is also a standard feature on the UG Dial governor. It limits
the amount of fuel supplied by restricting the travel of the governor output shaft.
An indicator dial shows the governor output shaft limit position.
The load limit control may also be used for shutting down the prime mover by
turning it to zero.

UG Dial Governor Manual 03040
2 Woodward
* UG-5.7—7.1 Nm (5.2 lb-ft)
* UG-8—13.2 Nm (9.7 lb-ft)
* UG-10—15.9 Nm (11.7 lb-ft)
Figure 1-2. Recommended Output Shaft Travel Adjustment
References
The publications listed below are available on Woodward’s website
(www.woodward.com). Some of the manuals are briefly covered in Chapter 7,
Auxiliary Equipment.
Pub. Pub.
Type Number Title
Manual 03013 Shutdown Solenoid for UG Governors
Manual 03016 Low Lube Oil Pressure Shutdown for UG Governors
Product Spec. 03029 UG-5.7/8/10 Governor
Manual 03035 PM Speed Adjusting Motor
Manual 03505 Speed Adjusting (Synchronizing) Motor Parts Catalog
and Lubrication Guide
Manual 25071 Oils for Hydraulic Controls
Manual 25075 Commercial Preservation Packaging for Storage of
Mechanical-Hydraulic Controls
Manual 36052 Magnetic Speed Pickup for PG, UG-8, and UG-40
Governors
Manual 36684 Booster Servomotor
Application Note 50516 Governor Linkage for Butterfly Throttle Valves
Repair Manual 56103 UG Dial Governor Repair Procedure

Manual 03040 UG Dial Governor Woodward 3
Figure 1-3. UG Dial Governor Outline Drawing

UG Dial Governor Manual 03040
4 Woodward
Chapter 2.
Installation Procedures
Introduction
This chapter provides information necessary for receiving, storage, mounting,
and start-up adjustments.
Receiving
When you receive your UG governor, it will be bolted to a wooden platform in a
vertical position. After testing the governor at the factory, it is drained of oil. This
leaves a light film of oil covering the internal parts, preventing rust. No internal
cleaning is required before installation.
Some drive shafts are sprayed with a light film of oil while others (depending on
customer requirements) are covered with soft seal. Before installation, remove
the soft seal with a rag saturated with mineral spirits.
Storage
If a governor is being stored for any period of time, please refer to Woodward
manual 25075, Commercial Preservation Packaging for Storage of Mechanical-
Hydraulic Controls.
Mounting Requirements
1. Make sure the drive shaft rotates freely.
2. Select the correct length of coupling between the governor and the prime
mover drive.
3. Mount the governor squarely on its mounting pad.
4. Make sure there is no force pushing the drive shaft into the governor.
5. See the outline drawing (Figure 1-3) for mounting hole sizes and governor
dimensions.
6. Make sure the coupling rotates freely but without backlash. Incorrect
alignment of the governor shaft to the coupling, or not enough clearance
between any of the parts, can result in excessive wear and/or seizure of
parts. It can also cause an undesirable high frequency vibration or “jiggle” in
the governor output shaft (see Definitions in Chapter 5 for more
information).

Manual 03040 UG Dial Governor
Woodward 5
The standard UG governor drive gives few installation problems if the alignment
of the governor shaft to the drive coupling is kept.
In the event of a misaligned or broken drive shaft, an overspeed
condition or runaway engine can develop. An overspeeding or
runaway engine can result in extensive damage to the equipment,
personal injury and/or loss of life.
If an optional keyed drive is used when installing the governor, take care to avoid
the following undesirable conditions:
a. Rough gear teeth:
Rough gear teeth, or shaft out of round, can cause vibrations which can
be transmitted to the governor and cause a jiggle in the governor
output shaft. The jiggle can be transmitted to the fuel control resulting
in an undesirable condition. Replace gears if necessary.
b. Incorrect shimming:
Check backlash and re-adjust if necessary to obtain proper mesh
without binding or excessive backlash. Refer to the prime mover
manufacturer’s specifications for the correct amount of backlash.
7. Mount the governor flush with the engine drive pad. If the engine drive pad
is at an angle (from 0° to 45° maximum), the UG must be installed with the
front panel in the upper position. Use a gasket between the governor and
the engine drive pad.
Be sure there is adequate space available around the governor to provide
easy access for installing the control linkage, filling the governor with oil, and
adjusting the speed and compensation system. See the outline drawing
(Figure 1-3) for mounting hole sizes and governor dimensions.
The recommended rated speed range for the governor drive is 1000 to 1500 rpm.
The drive power requirement is 249 W (1/3 hp) at normal speed and operating
temperature. The UG governor may be driven either clockwise or
counterclockwise.
Operating temperature range for the UG governor is –29 to +99 °C (–20 to +210 °F).
Linkage Attachments
Adjustment of the fuel linkage must provide for control of fuel from “OFF” to
“FULL FUEL” within the limits of the 42° of governor output shaft travel. It must
also provide for approximately 30° output shaft travel between “NO LOAD” and
“FULL LOAD”.
Attach the fuel rack linkage to the governor output shaft. There must be no lost
motion or binding in this linkage. Adequate locking methods must be employed
on the linkage connections.
Be sure to allow sufficient overtravel at each end of the terminal shaft.
Failure to provide sufficient overtravel at maximum fuel position can
prevent the prime mover from giving maximum fuel when required.
Failure to provide sufficient overtravel at minimum fuel position can
prevent the governor from shutting down the prime mover and result
in possible damage to equipment and personal injury.

UG Dial Governor Manual 03040
6 Woodward
A linear linkage arrangement is used in applications where the governor output
shaft positioning is directly proportional to the torque output of the prime mover.
Thus, the governor output shaft travel will be directly proportional to the amount
of fuel delivered to the prime mover.
A linear linkage is a linkage arrangement which provides as much movement of
the governor output shaft per increment of valve movement at light loads as it
does at heavy loads.
In applications where a governor is controlling a butterfly valve, such as on a gas
engine, a linear linkage should not be used.
This is due to the inherent design of the butterfly valve which requires only a
small amount of valve travel (for example, 10°) to bring an engine from no load to
half load. By contrast, this design requires a much greater movement of valve
travel (for example, 30°) to bring the engine from half load to full load.
In order to improve governing control at light loads, a compensating linkage is
devised (“non-linear” linkage). This linkage provides greater movement of the
governor per increment of valve movement at light loads than it does at heavy
loads. Figure 2-1 illustrates the relationship between governor output shaft and
butterfly positions obtained with simple linkage of maximum non-linearity. When
installing this linkage, make sure that the two following conditions are obtained
when the linkage is in the no-load position:
1. The lever which is attached to the governor and the connecting link is in line
with the governor output shaft and the point of attachment of the connecting
link to the butterfly lever.
2. The butterfly lever must be at 90° with the connecting link.
See also Table 5-2 for a satisfactory relationship between governor output shaft
travel and butterfly valve travel in a non-linear system.
For more information on non-linear linkage, please refer to Woodward
Application Note 50516, Governor Linkage for Butterfly Throttle Valves.
Figure 2-1. Linkage Arrangement (for non-linear fuel systems)

Manual 03040 UG Dial Governor
Woodward 7
Oil Supply
Use an oil depending on operating temperature for the governor (see Table 2-1).
Primary concern is for the oil properties in the governor.
Fill the governor with approximately two quarts of oil to the mark on the oil sight
glass. After the engine is started and the governor is at operating temperature,
add oil if necessary. Oil must be visible in the glass under all operating
conditions.
Use the information given in Tables 2-1 and 2-2 as a guide in the selection of a
suitable lubricating/hydraulic oil. Oil grade selection is based on the operating
temperature range of the governor. Also, use this information to aid in
recognizing and correcting common problems associated with oils used in
governors.
For applications where the governor shares the oil supply with the engine, use
the oil recommended by the engine manufacturer.
Governor oil is both a lubricating oil and a hydraulic oil. It must have a viscosity
index that allows it to perform over the operating temperature range, and it must
have the proper blending of additives that cause it to remain stable and
predictable throughout this range.
Governor oil must be compatible with seal materials (particularly nitrile,
polyacrylic, and fluorocarbon). Many automotive and gas engine oils, industrial
lubricating oils, and other oils of mineral or synthetic origin meet these
requirements. Woodward governors are designed to give stable operation with
most oils with the viscosity, at the operating temperature, between 50 and 3000
SUS (Saybolt Universal Seconds). At the normal operating temperature, the
viscosity should be between 100 to 300 SUS. Poor actuator response or
instability may be an indication that the oil viscosity is outside this range.
Excessive component wear or seizure in a governor indicates the possibility of:
1. Insufficient lubrication caused by:
a. An oil that flows slowly when it is cold, especially during start-up.
b. No oil in the governor.
2. Contaminated oil caused by:
a. Dirty oil containers.
b. A governor exposed to heating up and cooling down cycles, which
creates condensation of water in the oil.
3. Oil not suitable for the operating conditions caused by:
a. Changes in ambient temperature.
b. An improper oil level which creates foamy, aerated oil.

UG Dial Governor Manual 03040
8 Woodward
Table 2-1. Oil Chart
Table 2-2. Viscosity Comparisons

Manual 03040 UG Dial Governor
Woodward 9
Operating a governor continuously beyond the high limit temperature of the oil
will result in oil oxidation. This is identified by varnish or sludge deposits on the
governor parts. To reduce oil oxidation, lower the actuator operating temperature
with a heat exchanger or other means, or change to an oil more oxidation-
resistant at the operating temperature.
A loss of stable governor control and possible prime mover
overspeed may result if the viscosity exceeds the 50 to 3000 SUS
range. An overspeeding and/or runaway prime mover can result in
extensive damage to the equipment, personal injury and/or loss of
life.
Specific oil viscosity recommendations are given on the oil chart (Table 2-1).
Select a readily available good brand of oil, either mineral or synthetic, and
continue using that same brand. Do NOT mix the different classes of oils. Oil that
meets the API (American Petroleum Institute) engine service classification in
either the “S” group or the “C” group, starting with “SA” or “CA” through “SF” and
“CD” is suitable for governor service. Oils meeting performance requirements of
the following specifications are also suitable: MIL-L-2104A, MIL-L-2104B, MIL-L-
2104C, MIL-L-46152, MIL-L-46152A, MIL-L-46152B, MIL-L-45199B.
Replace the governor oil if it is contaminated, also change it if it is suspected of
contributing to the governor instability. Drain the oil while it is still hot and
agitated; flush the governor with a clean solvent having some lubricating quality
(such as fuel oil or kerosene) before refilling with new oil. If drain time is
insufficient for the solvent to completely drain or evaporate, flush the governor
with the same oil it is being refilled with to avoid dilution and possible
contamination of the new oil. To avoid recontamination, the replacement oil
should be free of dirt, water, and other foreign material. Use clean containers to
store and transfer oil.
Observe the manufacturer’s instructions or restrictions regarding the
use of solvents. If no instructions are available, handle with care. Use
the cleaning solvent In a well ventilated area away from fires or
sparks.
Failure to follow the safety instructions above can result in
dangerous fires, extensive damage to equipment, personal injury
and/or loss of life.
Oil that has been carefully selected to match the operating conditions and is
compatible with governor components should give long service between oil
changes. For governors operating under ideal conditions (minimum exposure to
dust and water and within the temperature limits of the oil), oil changes can be
extended. If available, a regularly scheduled oil analysis is helpful in determining
the frequency of oil changes.
Any persistent or recurring oil problems should be referred to a qualified oil
specialist for solution.
The recommended continuous operating temperature of the oil is 60 to 93 °C
(140 to 200 °F). The ambient temperature limits are –29 to +93 °C (–20 to +200
°F). Measure the temperature of the governor on the outside lower part of the
case. The actual oil temperature will be slightly warmer, approximately 6 °C
(10 °F).

UG Dial Governor Manual 03040
10 Woodward
Chapter 3.
Principles of Operation
Introduction
Basic UG operation is similar for all types. The only difference is in the method of
setting the speed. Auxiliary devices provide different functions but do not alter the
basic operation of the governor.
Along with the text, a schematic diagram (Figure 3-1) is provided for visual
means of understanding the operation of the UG Dial governor. This schematic
shows a basic design and does not include any auxiliary equipment.
Component Description
Before getting into the operation of the UG, a brief description of the components
will facilitate understanding the operation.
Oil Pump
The purpose of the oil pump (14) is to provide oil pressure for the governor.
The pump gets its oil from the self-contained sump (15). The oil pump is a
positive displacement gear pump with four check valves (13) for either direction
of rotation. One pump gear is part of the rotating bushing, and the other is part of
the laminated drive. The rotating bushing is driven by the governor drive shaft
which is driven by the prime mover. As the bushing rotates, it rotates the
laminated drive. The oil pump gears can be driven either clockwise or
counterclockwise.
Oil flow is directed through the check valve system into the accumulator system
(11).
Accumulator
The purpose of the accumulator (11) is to store oil under pressure for the
operation of the UG governor. The accumulator (two cylinders) also acts as a
pressure relief valve if oil pressure increases above 827 kPa/120 psi (UG-5.7 and
UG-8) or 1034 kPa/150 psi (UG-10).
The accumulator (11) consists of two spring loaded pistons. Oil is pumped into
the cylinders and pressure is increased as the accumulator springs are
compressed. When the oil pressure exceeds 827 kPa/120 psi (UG-5.7 and
UG-8), or 1034 kPa/150 psi (UG-10), oil is released back to sump through a relief
port (12) in each cylinder.
Oil flows from the accumulator through passages to the top of the power piston
and to the pilot valve system.

Manual 03040 UG Dial Governor
Woodward 11
Power Piston
The purpose of the power piston (9) is to rotate the governor output shaft to the
increase or decrease fuel position.
The power piston is a differential type with oil pressure on both sides of the
piston. The top end of the power piston is connected to the governor output shaft
(6) through a power lever and link assembly.
The bottom of the power piston has a larger area than the top of the piston.
Therefore, less oil pressure is needed on the bottom than on the top to maintain
the piston stationary. If the oil pressure is the same on both the top and bottom of
the piston, the piston moves up to rotate the governor output shaft in the increase
fuel direction. The piston moves down only when oil under the piston is released
to sump.
Oil to and from the bottom of the power piston is regulated by the pilot valve
system.
Pilot Valve System
The purpose of the pilot valve plunger and bushing is to control the flow of oil to
or from the bottom of the power piston.
The pilot valve system includes the rotating bushing (38) and the pilot valve
plunger (39). The bushing (38) is rotated by the drive shaft (36) while the pilot
valve plunger is held stationary. Through this rotation, friction between the pilot
valve and bushing is reduced. The pilot valve plunger has a control land that
regulates oil flow through ports in the bushing.
When the pilot valve plunger (39) is lowered, high pressure oil flows under the
power piston (9), raising it. When the pilot valve plunger is raised, oil is released
to sump from under the power piston (9), lowering it. The higher pressure on top
of the power piston(9) forces the piston down. When the pilot valve plunger (39)
is in its centered position, the control land covers the control port as shown in the
schematic (Figure 3-1), and there is no movement of the power piston.
The movement of the pilot valve plunger (39) is controlled by the ballhead system
(23) and the dashpot compensation pistons (34) and (35).
Ballhead System
The purpose of the ballhead system (23) is to sense speed changes of the prime
mover as compared to the speed setting reference given by the speeder spring
(25) and to position the pilot valve plunger (39).
The ballhead system includes a ballhead (23), flyweights (24), a speeder spring
(25), a thrust bearing (30), a speeder plug (29),and a speed setting rod (21).
As the governor drive shaft (36) rotates, the gear on the laminated drive (32)
turns and rotates the ballhead gears (23). The flyweights (24) are attached to the
ballhead with pivot pins, and a thrust bearing (30) rides on the toes of the
flyweights (24). The speeder spring (25) is held in position against the thrust
bearing (30) by the speeder plug (29). The speeder plug (29) is used to set a
pressure on the speeder spring (25).

UG Dial Governor Manual 03040 12 Woodward Figure 3-1. UG Dial Governor Schematic Diagram

Manual 03040 UG Dial Governor
Woodward 13
As the ballhead (23) rotates, the flyweights (24) pivot outward due to the
centrifugal force. At the same time the speeder spring (25) forces the thrust
bearing (30) downward on the flyweight toes. This downward force opposes the
centrifugal force of the flyweights. Increasing the drive speed increases the
centrifugal force. Compressing the speeder spring (25) with the speeder plug
(29) increases the downward force applied to the flyweight toes, and in turn,
increases the governor speed setting. The prime mover must run faster to
generate a centrifugal force greater than the speeder spring force to balance the
system again.
Speeder spring force or speed setting (25) is controlled manually through the
synchronizer (speed setting) adjusting knob (5). It can also be controlled from a
remote area if the governor is equipped with a speed setting motor (1).
Compensation System
The purpose of the compensation system is to give stability to the governor and
obtain steady state speed control. Also, when correctly adjusted, the
compensation system effectively regulates the amount of fuel necessary to bring
the engine to the required output to adjust to a decrease or increase in load.
The compensation system creates a small temporary change of speed setting
with governor output shaft movement to produce a stabilizing speed droop
characteristic in the governor. The change of speed setting is followed by a slow
return of speed setting to its original value. Compensation is simply another word
for temporary speed droop characteristic.
The compensation system includes a large dashpot compensation piston (34), a
small dashpot compensation piston (35), a floating lever (31), a compensation
adjusting lever (22) with a pivotable fulcrum (18), and a needle valve (33). See
Figure 3-1.
The large dashpot compensation piston (34) is connected to the governor output
shaft (6) by a compensation adjusting lever (22). A pivotable fulcrum (18) rides
on the compensation adjusting lever (22). Changing the fulcrum’s (18) position
allows the compensation lever (22) to control the amount of stroke available for
the large dashpot compensation piston (34).
The small dashpot compensation piston (35) is connected through a floating
lever (31) to the pilot valve plunger (39) and the speeder rod (21).
Moving the large dashpot compensation piston (34) down forces oil under the
small dashpot compensation piston (35). As the small dashpot compensation
piston (35) is forced upward, it lifts the pilot valve plunger (39) to close off the
control port which stops the flow of oil to the bottom of the power piston (9).
The needle valve (33) is a variable orifice which controls the flow of oil between
both the large (34) and the small dashpot compensation (35) pistons, and the oil
sump.
Compensation must be properly adjusted to the particular engine
and load to provide stable operation (see Chapter 4, Compensation
Adjustments).

UG Dial Governor Manual 03040
14 Woodward
Load Limit Control
The purpose of the load limit control is to hydraulically and mechanically limit the
load that can be placed on the engine by restricting the travel of the governor
output shaft in the increase fuel direction, and consequently the amount of fuel
supplied to the engine.
The load limit control may also be used for shutting down the engine by turning it
to zero.
Do not manually force prime mover linkage to increase fuel without
first turning the load limit control knob to maximum position (10).
Failure to do so may cause damage and/or failure of governor
internal parts.
The load limit control consists of an indicator disc (7) geared to a load limit rack
(8). The control knob is also attached to the load limit cam (16).
Load is limited mechanically by positioning the load limit knob (cam 16). When
the load indicator reaches the preset point, the pilot valve plunger (39) is lifted,
stopping any further increase in fuel.
Turning the load limit control to zero to shut down the engine turns the cam (16)
forcing the load limit (shutdown) lever (20) and shutdown strap (17) down. As the
right end of the load limit (shutdown) lever (20) is forced downward, it pivots
about its fulcrum and lifts the pilot valve plunger (39), releasing oil from under the
power piston (9). Pressure oil acting on top of the power piston (9) forces it
downward, rotating the governor output shaft (6) to minimum fuel and causing
the prime mover to shut down.
Synchronizer
The synchronizer is the speed adjusting control, and is used to change engine
speed for a single unit. On engines paralleled with other units, it is used to
change engine load.
The upper knob (called “SYNCHRONIZER” on most models or “SPEED
SETTING KNOB” on later models) is the control knob.
The lower knob (“SYN. INDICATOR”) has no function of its own but has an
indicator disc which shows the number of revolutions of the synchronizer (speed
setting) control knob.
Speed Droop
Speed droop, or simply droop, is one method of creating stability in a governor.
Droop is also used to divide and balance load between units driving the same
shaft or paralleled in the electrical system.
Droop is the decrease in speed that occurs when the governor output shaft
moves from the minimum to the maximum fuel position in response to a load
increase, expressed as a percentage of rated speed.
If instead of a decrease in speed, an increase takes place, the governor shows a
negative droop. Negative droop will cause instability in a governor.