GOVERNORS AND ENGINE CONTROLS
10A1. Function and types of governors.
The purpose of a governor is to control the
speed of an engine. If an engine is loaded beyond its rated capacity, it will slow down or
may even stop. Governors act through the
fuel injection system to control the amount
of fuel delivered to the cylinders. The quantity
of fuel delivered, in turn, governs the power
The two types of governors, each of which
serves a distinctly different purpose, are the
overspeed governor and the regulating governor.
The overspeed type is used on most marine engines where the speed of the engine is variable.
By necessity, the marine engine requires a flexibility in speed due to the maneuvering of the
ship. This type of governor is installed as a
safety measure and comes into action when the
engine approaches dangerous overspeed. This
condition could occur before the operator had
time to bring the engine under control by other
means. The overspeed trip functions only if the
regulating governor fails. This governor controls
all abnormal speed surges.
Overspeed governors are of the centrifugal
type; that is, the action of the governor depends
upon the centrifugal force created as the governor weights revolve. Centrifugal force is the
force that tends to move a body away from the
axis about which it is revolved. This force is
transmitted to the fuel injection system by
means of levers connected to the governor collar and a linkage system. In some types of overspeed governors the action merely cuts off the
fuel until the engine has slowed to a point of
safety and then allows the resumption of normal
operation. The other type trips a fuel cutout
mechanism and effects a complete stopping of
the engine. The F-M engines employ an F-M
design overspeed governor and the GM engines
use Woodward overspeed governors.
For this discussion governors will be classified as either hydraulic or mechanical. The mechanical type embodies the principle of centrifugal
force similar to the overspeed type, while
the hydraulic type employs a centrifugally actuated pilot valve to regulate the flow of a hydraulic medium under pressure. The mechanical
governor is more applicable to the small engine
field not requiring extremely close regulation
while the hydraulic type finds favor with the
larger installations demanding very close regulation. The regulating governor is much more
sensitive to slight speed fluctuations than is the
overspeed governor. Its duty is to control the
speed within very narrow limits when an engine
is operating under varying loads. It takes the
place of the operator's manual control of the
throttle. When the load on the engine increases,
and before the engine's speed has appreciably
dropped, it permits an increase of fuel to the
cylinders, thus maintaining the engine speed at
the set rate. To perform this function, the governor must be sensitive to the slightest variation
in speed. The Woodward hydraulic governor of
the regulating type is widely used in the United
States Navy and will be described in detail.
10A2. Submarine shipboard control installations. Each main and auxiliary submarine
engine installation includes a regulating and an
overspeed governor. Both of these governors
perform their function by actuating the fuel injection pump controls in some manner. The engines may be stopped at the throttleman's station at the engine or pneumatically by remote
control from the control cubicle.
Engine speeds are held uniform by regulating governors whose power mechanism transmits movement to the fuel control shift on the
engine. These main engine governors may be
controlled at the engine or in the control cubicle.
A control cabinet mounted on the main control
cubicle instrument panel in the maneuvering
room permits remote control of the governors
through a Selsyn installation.
The engines are prohibited from exceeding
a given maximum allowable speed by the
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overspeed governors which are either of hydraulic
or centrifugal type and driven off one of the
engine camshafts. The means by which these
overspeed trips fulfill their purpose are different for the GM and F-M engines and will be
explained later in this chapter.
B. REGULATING GOVERNORS|
10B1. Description and operation. The type
of regulating governor used on all submarine
main engines is the Woodward SI hydraulic
type governor. On F-M engines, it is driven from
the lower crankshaft, and on GM engines, from
one of the camshafts. The purpose of the governor is to regulate the amount of fuel supplied
to the cylinders so that a predetermined engine
speed will be maintained despite variations in
load. Figure 10-2 is a schematic diagram of the
governor. The principal parts of the governor
are a gear pump and accumulators which serve
to keep a constant oil pressure on the system at
all times; a pilot valve plunger, pilot valve bushing, and flyweights which control the amount of
oil going to the power assembly; a speed adjusting spring whose tension governs the speed
Figure 10-1. Woodward regulating governor installed.
setting of the governor; the power element, consisting of the power spring, power piston, and
power cylinder; and the compensating assembly
which consists of the actuating compensating
plunger, the receiving compensating plunger,
the compensating spring, and two compensation
needle valves. The pilot valve plunger is constructed with a land which serves to open or
close the port in the pilot valve bushing leading
to the power cylinder.
In this governor the flyweights are linked
hydraulically to the fuel control cylinder. The
downward pressure of the power spring is balanced by the hydraulic lock on the lower side
of the power piston. The amount of oil below
the power piston is regulated by the pilot valve
plunger controlled by the flyweights.
When the engine is running at the speed
set on the governor, the land on the pilot valve
plunger covers the regulating port in the bushing. The plunger is held in this position by the
flyweights. However, if the engine load decreases, the engine speeds up and the additional
centrifugal force moves the flyweights outward,
raising the pilot valve plunger. This opens the
regulating port of the bushing, and trapped oil
from the power cylinder is then allowed to flow
through the pilot valve cylinder into a drainage
passage to the oil sump. As the trapped oil
drains to the oil sump, the power spring forces
the piston down, actuating the linkage to the
fuel system controls, and the supply of fuel to
the engine is diminished. As the engine speed
returns to the set rate, the flyweights resume
their original position and the, pilot valve
plunger again covers the regulating port.
If the load increases, the engine slows
down, and the flyweights move inward. This
lowers the pilot valve plunger, allowing pressure
oil to flow through the pilot valve chamber to
the power cylinder. This oil supplied by a pump
is under a pressure sufficient to overcome the
pressure of the power spring. The power piston
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Figure 10-2. Schematic diagram of Woodward regulating governor.
moves upward, actuating the linkage to increase
the amount of fuel injected into the engine cylinders. Once again, as the speed returns to the
set rate, the flyweights resume their central position. The gear pump that supplies the high-pressure oil is driven from the governor drive
shaft and takes suction from the governor oil
sump. A spring-loaded accumulator maintains
a constant pressure of oil and allows excess oil
to return to the sump.
To prevent overcorrection in the regulating governor a compensating mechanism is used.
This acts on the pilot valve bushing so as to
anticipate the pilot valve movement and close
the regulating port slightly before the centrifugal
flyballs would normally direct the pilot
valve to cover the port. A compensating plunger
on the power piston shaft moves in a cylinder
that is also filled with oil. When the engine
speed increases and the power piston moves
downward, the actuating compensating plunger
is also carried down, drawing oil into its cylinder. This creates a suction above the receiving
compensating plunger which is part of the pilot
valve bushing. The bushing moves upward,
closing the port to the power piston. Thus the
power piston is stopped, allowing no time for
overcorrection. As the flyweights and pilot valve
return to their central position, oil flowing
through a needle valve allows the compensating
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Figure 10-3. Governor cross section-normal speed, steady load.
Figure 10-4. Governor cross section-increased speed, decreased load.
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spring to return to its central position. To keep
the port closed, the bushing and plunger must
return to normal position at exactly the same
speed. Therefore, the needle valve must be adjusted so that the oil passes through at the required rate for the particular engine.
When the engine speed drops below the set
rate, the actuating compensating plunger moves
upward with the power piston. This increases
the pressure above the actuating compensating
plunger and consequently above the receiving
compensating piston which therefore moves
down, carrying with it the pilot valve bushing.
As before, the lower bushing port is closed. The
excess oil in the compensating system is now
forced out through the needle valve as the compensating spring returns the bushing to its central position.
The governing speed of the engine is set
by changing the tension of the speed adjusting
spring. The pressure of this spring determines
the engine speed necessary for the flyweights to
maintain their central position. Oil allowed to
leak past the various plungers for lubricating
purposes is drained into the governing oil sump.
In actual operation, the events described
above occur almost simultaneously.
Figures 10-3 through 10-9 show actual
cross sections of the governor for various engine
loads and engine speeds. Figures 10-3 through
10-6 illustrate the actual governor operation
cycle for a decrease in the engine load. Figure
10-3 shows the governor operating with the
engine at normal speed under a steady load.
The flyballs, pilot valve plunger, and pilot valve
bushing are in normal positions. The regulating
port in the bushing is covered by the land on
the plunger. Thus the power piston is held stationary by the trapped oil.
Figure 10-4 shows the governor acting in
response to a load decrease and a consequent increase in speed. As the speed increases, the fly
balls move outward, raising the pilot valve
plunger so that its land uncovers the lower or
regulating port in the pilot valve bushing. This
releases the trapped oil from the power cylinder
and permits it to flow through the regulating
port to the sump. The power spring is thus allowed to move the power piston downward and
consequently reduce the fuel supply to the engine, thereby decreasing the engine speed.
The downward motion of the power piston
reduces the fuel supply and thereby reduces the
engine speed as described above. However, to
prevent this reduction from being carried too
far, the actuating compensating piston moves
down with the power piston as shown in Figure
10-5. This creates an oil suction on the receiving compensating piston which draws up the
pilot valve bushing, compressing the compensating spring. Movement of the power piston
and pilot valve bushing continues until the
lower or regulating port in the bushing is covered by the land on the pilot valve plunger. As
soon as the regulating port is covered, the power
piston is stopped at a position corresponding to
the decreased fuel needed to run the engine at
the reduced load.
As the speed decreases to normal, the flyballs return to their normal position, thus lowering the pilot valve plunger to its normal position as shown in Figure 10-6. To keep the
regulating port closed while the plunger is being
returned to normal position, the bushing must
move downward at the same rate as the plunger.
This is done by the compensating spring. The
flow of oil through the needle valve determines
the rate at which the compensating spring is
able to move the bushing. Thus, it can be seen
that accurate governing is dependent on a
proper adjustment of the needle valve since any
opening in the regulating port during this phase
of the cycle would permit the power piston to
move, thereby causing an undesirable change
in the fuel supply.
At the completion of the cycle, the flyballs,
pilot valve plunger, and pilot valve bushing
have returned to normal position. The power
piston is stationary, held by trapped oil, in a
position corresponding to the decreased fuel
needed to run the engine at normal speed under
a decreased load.
Figure 10-7 shows the governor acting in
response to an increase in load with a resulting
decrease in engine speed. As the speed decreases,
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Figure 10-5. Governor cross section-normal speed, decreased load.
Figure 10-6. Governor cross section-normal speed, new load.
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the flyballs move inward, lowering the pilot
valve plunger and uncovering the regulating
port in the pilot valve bushing. Thus, pressure
oil from the pump and the accumulators is admitted to the power cylinder, causing the power
piston to move up and increase the flow of fuel.
As the power piston moves up (Figure
10-8), the actuating compensating piston also
moves up, causing oil pressure on the receiving
compensating piston and thereby forcing the
pilot valve bushing down, compressing the compensating spring. Movement of the power piston
and the pilot valve bushing continues until the
regulating port in the bushing is covered by the
land on the pilot valve plunger. As soon as
the regulating port is covered, the power piston
is stopped (oil being trapped under the piston)
at a position corresponding to the increased
fuel needed to run the engine at normal speed
under an increased load.
As the speed increases to normal, the flyballs return to their normal position, raising the
pilot valve plunger back to its normal position
(Figure 10-9). The pilot valve bushing is returned to its normal position by the compensating spring at the same time and rate as the pilot
valve plunger. This keeps the regulating port
covered by the land on the plunger, thus keeping the power piston stationary. The flow of oil
through the needle valve determines the rate at
which the bushing is returned to normal. At
the completion of the cycle, the flyballs, pilot
valve plunger, and pilot valve bushing are in
their normal position. The power piston is stationary at a position corresponding to the increased fuel needed to run the engine at normal
speed under the increased load.
10B2. Regulating governor sub-assemblies.
The governor consists of five principal subassemblies as follows:
a. Drive adapter. The drive adapter assembly serves as a mounting base for the governor. The upper flange of the casting is bored
out at the center to form a bearing surface for
the hub of the pump drive gear and for the
upper end of the drive shaft.
The drive shaft assembly is flexible in
order to keep from the governor, as far as possible, the inherent vibrations of the camshaft
from which the governor is driven. This shaft is
so constructed that the power required to drive
the governor is transmitted from the serrated
drive sleeve through the drive pin to the lowest
section of the plug, and from the lower section
through leaf springs to the upper section of the
drive shaft. The governor drive is made positive,
even if the springs should break, by the construction of the two sections of the shaft. Each
section is cut with a projection on the end. In
the event of leaf spring failure, these projections
will make contact and continue to drive the
b. Power case assembly. This assembly includes the governor oil pump, oil pump check
valves, oil pressure accumulators, and compensating needle valves.
The oil pump drive gear turns the rotating
sleeve to which it is attached. The pump idler
gear is carried on a stud and rotates in a bored
recess in the power case. These two gears and
their housing constitute the governor oil pump.
On opposite sides of the central bore in the
power case, and parallel to it, are two long oil
passages leading from the bottom of the power
case to the top of the accumulator bores. Check
valve seats are arranged at the top and bottom
of each chamber. Both check valves have openings leading from the space between the valves
to the oil pump. In this way the pump is arranged for rotation in either direction, pulling
oil through the lower check valve on one side
and forcing it through the upper check valve on
the opposite side.
There are two oil pressure accumulators.
Their function is to regulate the operating oil
pressure and insure a continuous supply of oil
in the event that the requirements of the power
cylinder should temporarily exceed the capacity
of the oil pump. There is no adjustment for oil
pressure, as this pressure is determined by the
size of the springs in the accumulators.
The two compensating needle valves control the size of the openings in the two small
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Figure 10-7. Governor cross section-decreased speed, increased load.
Figure 10-8. Governor cross section-normal speed, increased load.
Figure 10-9. Governor cross section-normal speed, new load.
Figure 10-10. Governor-sections through adapter, power, case, power cylinder and rotating sleeve assembly.
Figure 10-11. Governor-section through speed control column.
Figure 10-12. Governor-section through accumulator cylinder.
tapered ports in the passage that connects the
area above the actuating compensating plunger
in the Servo motor and the space above the
receiving compensating plunger in the pilot
valve bushing of the rotating sleeve assembly.
These ports open the compensating oil passage
to the oil sump tank. Only one needle valve and
one port are necessary for operation, but two are
provided so that adjustment can be made on the
one that is more accessible.
c. Power cylinder assembly. The power
cylinder assembly consists of the cylinder,
power piston, piston rod, power spring, and the
actuating compensating plunger. The power
piston is single acting. Any oil pressure acting
on the lower side forces the piston up against
the power spring, thereby increasing the fuel
flow. If no oil pressure is present, the power
spring acting on the upper side forces the piston
down to decrease the fuel flow.
The area underneath the power piston is
connected to the pilot valve regulating ports.
An oil drain is provided in the space above
the power piston to permit any oil that may leak
by the piston to drain into the governor case oil
sump. No piston rings are used in the closely
fitting piston. A shallow, helical groove permits
equal oil pressure on all sides of the piston, thus
preventing wear and binding.
An adjustable load limit stop screw is provided in the power cylinder. This screw prevents
the power piston from traveling beyond the predetermined load limit. The screw can be adjusted by removing the cap nut on top of the
power cylinder, loosening the lock nut, and
turning the screw up or down with a screwdriver.
d. Speed control column. The basic speed
control column assembly includes the speeder
plug screw, speed adjusting spring, rack shaft,
rack shaft gear, and the speed adjustment knob
with gear train. The gear train consists of the
dial shaft gear, dial shaft pinion, and the pinion
shaft gear and pinion. Movement of the gear
train changes the compression of the speed adjusting spring. The amount of compression determines the speed at which the flyballs will be
vertical. Hence, the compression determines the
engine speed. The speeder plug screw allows the
adjustment of the governor speed setting to
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match the actual speed of the engine.
e. Rotating sleeve assembly. The principal
parts of the rotating sleeve assembly (Figure
10-13) are: the pump drive gear, pilot valve
bushing, pilot valve plunger, ballhead, and flyballs. The central bore in the power case forms
a bearing for the entire rotating sleeve. The
port grooves in the sleeve align with the ports
in the power case (Figure 10-10). Since these
grooves extend completely around the diameter
of the rotating sleeve, the results are the same
as if the sleeve were stationary and the ports
were permanently in line with those in the case.
From top to bottom the ports are as follows:
accumulator pressure to pilot valve, regulating
pressure to power cylinder, drain from the
lower end of the pilot plunger, compensating
pressure from the power piston to the receiving
compensating plunger on the pilot valve bushing, and drain from the lower side of the receiving
In the 1/2-inch and 1-inch diameter bores
in the rotating sleeve are the pilot valve bushing and receiving compensating plunger, the
compensating spring retainer, two compensating
spring collars, compensating spring, and adjusting nut.
The nut is threaded on the stem at the
lower end of the pilot valve bushing just tightly
enough so that the compensating spring is
slightly compressed between the collars, and so
that the dimension between the outer faces of
the spring collars exactly equals the depth of
the 1-inch hole in the spring retainer. With the
nut in this position, the face of the lower spring
collar will be flush with the lower end of the
compensating spring retainer and the upper end
of the pump drive gear, and there will be no
movement of the pilot valve bushing without
compression of the spring.
Figure 10-13. Governor-rotating sleeve assembly.
Figure 10-14. Governor-speed control mechanism.
The pilot valve plunger land slightly overlaps, the regulating ports in the valve bushing.
Therefore any slight movement of the valve
will produce a corresponding power piston
The ball bearing clamped between the
spring collar and the upper shoulder serves as a
support for the ballarm fingers. Mounted on
ball bearings, the flyballs are free to move at
the slightest change in speed, and their motion
is transmitted to the pilot valve through the
horizontal fingers on the ballarms.
10B3. Adjustments. a. Speed adjustment. The
speed setting of the governor is changed by increasing or decreasing the compression of the
speed adjusting spring which opposes the centrifugal force of the flyballs. Increasing the
spring compression will make it more difficult
for the flyballs to move outward; consequently
a higher flyball (and engine) speed must be
attained to move the flyballs outward and thereby reduce the fuel supply.
Conversely, decreasing the compression of
the speed adjusting spring will permit the flyballs to move outward when they, and the engine, are running at a lower speed. Thus, decreasing the spring compression decreases the
speed at which the engine will run.
Speed adjustments may be made manually
at the governor, or electrically from the governor control cabinet in the maneuvering room
1. Manual adjustment. The manual adjustment is made by means of the speed control
knob located on the front of the regulating governor. This knob is connected through a gear
train to the rack shaft which in turn is- geared to
a rack on the speed adjusting plug. The knob
also actuates a pointer that travels over a dial
graduated to show engine speeds corresponding to deflection of the speed adjusting spring.
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2. Electrical adjustment. For electrical control, a Selsyn receiving motor is also geared to
the rack shaft. This receiving motor operates in
parallel with a Selsyn transmitter generator in
the governor control cabinet mounted on the
main control cubicle instrument panel in the
maneuvering room. When the speed setting is
changed at the transmitter generator, the receiving motor in the governor moves to establish the
same setting in the governor.
b. Compensating needle valve adjustment.
This adjustment is made with the engine running from 200 rpm to 300 rpm as set by the
speed adjustment knob or by remote control.
Either of the two needle valves may be
used for adjustment. The one not used must be
turned in against its seat. When performing the
adjustment, the more accessible valve is opened
a full turn or more and the engine is allowed
to surge for approximately 30 seconds to eliminate trapped air. Then the valve is closed until
surging is just eliminated.
The needle valve will usually be open
about one-fourth of a turn for best performance.
However, the adjustment depends on the characteristics of the engine. The needle valve
should be kept open as far as possible to prevent sluggishness. Once the valve has been adjusted correctly for the engine, it should not be
necessary to change the adjustment except for
a permanent temperature change affecting the
viscosity of the oil.
10B4. General maintenance and internal
adjustments. a. Oil changes. The governor
oil must be clean and free of foreign particles.
Under favorable conditions the oil may be used
for approximately 6 months without changing.
If adjustment of the compensating needle valve
does not result in proper operation, dirty oil
may be the cause of the trouble.
To change the oil, remove the governor
from the engine as follows:
1. Disconnect all electrical connections to
the governor. Tag the wires and connecting
points to make certain connections will be properly replaced.
2. Remove the clevis pin from governor
link and power piston tail rod connection.
3. Remove the nuts that hold the governor
to the governor and tachometer drive housing.
4. Lift the governor straight up, being careful not to damage the splined shaft.
With the governor removed from the engine, remove the cover, turn the governor upside
down, drain and flush thoroughly with clean
light-grade fuel oil or an approved solvent solution to remove any foreign matter. Drain thoroughly, flush and refill with clean lubricating
oil. Follow the above procedure whenever the
governor is removed from the engine for any
If it is not possible to shut down long
enough to remove the governor from the engine, drain the oil from the governor by removing one of the plugs in the lower part of the
power case. Fill with fuel oil and run for approximately 30 seconds with the needle valve
open. Then drain and refill with clean lubricating oil.
b. Oil seals. When it becomes necessary to
add oil to the governor too frequently, the oil
seals should be replaced. To replace the drive
shaft oil seal, remove the lockwire and capscrews that secure the drive shaft assembly to
the base, then pull the assembly out of the base.
Remove the snap ring and press the drive shaft
out of the bearing. Remove the bearing retainer
and press out the oil seal. Carefully press the
new seal into the retainer and reassemble the
unit. Make sure the lip of the new seal faces
To replace the piston rod oil seal, remove
the power cylinder from the governor. Drive out
the tapered pin and press the piston rod out of
the rod end. Remove the cylinder head, pry out
the oil seal and press a new seal into position
making certain that the oil seal lip faces upward.
Reassemble the unit being careful not to
damage the lip of the new seal.
c. Ballarms and bearings. Erratic governor performance may indicate the need for replacement of ballarms, ballarm bearings, or pilot
valve plunger bushing.
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If the toes of the ballarms are worn too.
badly to be refinished, new ballarms should be
installed. Set the flyballs at the same position on
the new ballarms as on the old ones. Ballarm
bearings should be replaced if worn excessively.
If the ballarm pins do not fit tightly in the inner
race of the ballarm bearings, they should be
interchanged with the ballarm stop pins.
If the pilot valve plunger bearing is
grooved, it should be either turned over or replaced. Extreme care must be used in disassembling the pilot valve plunger assembly, to
avoid damaging the ground finish. After disassembly and reassembly of the pilot valve
plunger assembly, the pilot valve adjustment
should be checked.
d. Pilot valve adjustment. The pilot valve
adjustments should be checked after doing any
work on flyballs, pilot valve plunger, or pilot
The regulating port should be completely
Figure 10-15. Governor-measurement
uncovered for both inner and outer positions of
Movement of the regulating land on the
plunger can be observed through the regulating
port in the bushing while holding the plunger
assembly against the toes of the ballarms and
moving the ballarms through their full travel.
The amount of port opening for inner and outer
positions of the flyballs should be the same and
correct within .005 inch. Openings need not be
completely uncovered at each extreme. If the
regulating port is not fully uncovered at each
end of ballarm travel, the position of the
plunger in relation to the ballarms can be
changed by varying the washer thickness under
the bearing on the plunger. Removing one layer
from the laminated washer will raise the
plunger a distance of 0.002 inch.
e. Pump drive gear end clearance. Pump
drive gear end clearance is determined by the
thickness of the laminated washers under the
Figure 10-16. Governor adjustment of
compensating spring length.
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rotating sleeve retainer. To obtain proper end
clearance of the pump drive gear, remove one
lamination at a time from the washer under
each end of the retainer until the rotating sleeve
assembly turns hard, then replace one lamination under each end. The clearance should be
from 0.001 to 0.003 inch. Insufficient end clearance will cause wear and possible seizure. Excessive clearance will reduce pump capacity.
After the laminated washers have been
completely removed, due to repeated adjustment, the retainer should be replaced. To replace the retainer, remove the rotating sleeve assembly from the power case and press the sleeve
out of the ballhead. Reassemble the unit using
a new retainer and new laminated washers. Adjust pump gear end clearance as before.
f. Compensating spring adjustment. Compensating spring adjustment should not be made
without first making the compensating needle
valve adjustment and changing the oil. Then, if
operation is still not satisfactory, remove the
tapered screws and pull out the drive gear and
pilot valve bushing assembly. Back off the adjusting nut and change the precompression on
the compensating spring.
This precompression may vary from 0.010
to 0.078 inch depending upon engine characteristics and load. To eliminate a slow engine hunt,
remove shims to reduce precompression. To
eliminate a surge, add shims to increase precompression.
Adjust compensating spring length and reassemble with the rotating sleeve and the drive
gear. Check for end play. None is allowed.
g. Speed limit adjustment. Speed limit adjustment must be made only after it has been
determined that the engine linkage is in proper
adjustment. If the desired maximum or minimum engine speed cannot be obtained by turning the speed adjusting knob, the limits can be
changed by turning the speed adjusting plug
screw. If the limits cannot be changed sufficiently by adjusting this screw, or if the adjusting plug is not equipped with such a screw, the
adjustment can be made by changing the position of the stop pins with respect to the speed
With the engine shut down, remove the
dial plate, dial shaft nut, speed adjusting knob,
and dial disk. While doing this, place a finger
against the inside end of the dial shaft to prevent its being forced through the bushing by the
dial shaft spring. Replace the knob and nut. Pull
the gear forward, unmeshing it from the pinion.
Start the engine and turn the speed adjusting knob to the desired maximum (or minimum) speed. Remesh the gear in position where
its maximum (or minimum) stop pin is against
the pin in the dial panel. Stop the engine, remove the nut and knob, and reassemble all
Note whether the engine speed, as shown
by the tachometer, corresponds to that shown
on the governor dial. If not, recheck the speed
10B5. Governor control cabinets. The purpose of the control cabinet is to permit adjustment of the speeds of any engine or any
Figure 10-17. Governor control cabinet.
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Figure 10-18. F-M governor drive.
combination of two or more engines from the
maneuvering room. There are two type of cabinets. The common type (Figure 10-17) is a
single unit that can control all four engines. The
split type found on some late fleet type submarines is composed of two units, each of which
normally controls two engines, but one unit may,
through a switching arrangement, control a
maximum of three or a minimum of one engine.
The control cabinets also mount electrical
The common type control cabinet contains
four Selsyn transmitter generators, one for each
main engine. Each of these transmitters is connected by three wires to a Selsyn receiving
motor in the regulating governors on the engines.
When a transmitter generator rotor is turned by
means of a knob on the control cabinet, the
phase relationship between the transmitter generator and its receiving motor is disturbed. This
causes the receiving motor, which is geared to
the rackshaft, to change the governor speed setting to that set on the knob on the control cabinet.
The speed setting of any of the four governors can be changed independently through a
unit control knob for each governor. For independent operation the cams on the knobs must
be in the latched position.
Any or all of the four unit control knobs
can be operated simultaneously and identically
by the master control knob at the center of the
control panel. To permit simultaneous operation, it is necessary to unlatch the cams on the
desired unit control knobs first. Next set the
speed of the engines together by means of the
unit control knobs as indicated by the tachometers, then relatch the cams. This meshes the
gears that link each unit control knob to the
master control knob.
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In the split type installation, two control
cabinets are installed to control the four main
engines. Normally one is used for control of the
two port engines and the other for control of
the two starboard engines.
By means of switches, it is possible to surrender control of one engine over to the other
control cabinet. Any one cabinet may control a
maximum of three engines or a minimum of one.
Each control cabinet contains two direct
current position motors, one for each of the engines on the same side of the ship as the control
cabinet, and one master position motor which
may be electrically interconnected with the
other control cabinet, or mechanically with the
position motors of its own pair of engines.
C. GOVERNOR DRIVES AND OVERSPEED GOVERNORS|
10C1. Governor drives. a. F-M flexible
drive. The governor and the fresh and salt water
circulating pumps, as well as the lubricating and
fuel oil pumps, are driven from the lower crankshaft through a flexible gear drive. The governor
drive (Figure 10-18) transmits power from the
coupling at the top of the flexible pump drive to
rotate the regulating governor. The coupling
shaft is designed to float between the pump
drive and the second intermediate drive shaft,
in order to absorb vibration that might pass
through the gear train from the lower crankshaft.
The ball bearings and gears of the governor drive are lubricated with oil thrown off
from the timing chain in the control end compartment.
b. GM governor and tachometer drive. On
the GM governor and tachometer drive (Figure
10-19), the governor is driven through bevel
Figure 10-19. Governor and tachometer drive, GM.
Figure 10-20. GM hydraulic Type overspeed governor.
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gears mounted in a housing on the camshaft
drive housing. The drive shaft is driven from
the camshaft gear through a flexible radial leaf
spring type coupling. This shaft drives a bevel
gear, through serrations in the shaft, which in
turn drives a mating gear, the hub of which
is serrated to fit the governor drive shaft. The
drive gear is housed in a carrier which also
includes a worm gear for the tachometer drive.
The entire assembly is enclosed in a bracket
housing bolted to the camshaft drive housing
and is lubricated with oil flowing through the
center of the camshaft. The generator bearing
scavenging pump, if used, is also driven through
In the event of spring failure in the flexible
coupling, a dowel pin in the driving member will
come into contact with the side of a wide groove
in the driven member and thus continue to
Figure 10-21. GM overspeed shutdown Servo motor.
10C2. Overspeed governors. a. Function.
Overspeed governors are provided to shut off
fuel to the engine in the event of regulating
governor failure, jammed linkage, or any other
cause that may prevent reduction of the fuel
flow by normal methods.
b. GM hydraulic type overspeed governor.
The hydraulic type overspeed governor is similar to the regulating governor. It also employs
the centrifugal force of a pair of flyballs acting
against the pressure of a spring raising and
lowering a plunger (Figure 10-20). The plunger
regulates the ports of a gear pump which can,
under certain conditions of engine speed, provide oil under pressure to a small Servo motor
at each injector rocker arm, causing the Servo
motors to stop the function of the injectors.
The overspeed governor is driven from the
camshaft of the engine. The drive shaft of, the
governor drives the gear pump and the flyballs.
At normal engine speeds the flyballs are not
acted upon by sufficient centrifugal force to
raise the plunger, therefore, the drain bypass
ports in the valve bushing remain open. Oil
discharged from the pump then flows through
a passage in the side of the case into the space
surrounding the plunger and through the valve
ports into the sump space. The oil level is held
at the top of the drain tube by metering the
engine lubricating oil that flows into the case. An
oil passage between the drive shaft housing and
the sump space in the case prevents pressure
from being built up by oil leaking from the
pump into the housing. Such pressure would
blow out the oil seal below the ball bearing.
When the engine reaches its maximum allowable overspeed of 107 percent of normal full
speed, the flyballs move outward from the normal center of rotation, raising the plunger
against the force of the trip spring to close the
drain bypass ports. Pressure built up by the
pump forces the oil through a tube to the top
pipe in the multiple manifold assembly on each
cylinder bank. The oil flows from the manifold,
through tubing, to a passage in the cylinder head
and under the piston of a Servo motor attached
to each cylinder head. The Servo motor actuates
a lever that holds down the injector rocker arm.
This action holds the cam roller on the injector
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Figure 10-22. F-M overspeed governor and emergency stop mechanism.
rocker arm clear of the injector cam on the camshaft and prevents the injector from operating.
The overspeed governor is equipped with a
latch on top of the governor case. This latch
holds the valve plunger in position to keep the
ports covered and therefore to keep the fuel
injectors locked. The latch must be reset manually by the operator before the engine can
again be started. This is accomplished by releasing the latch and by pushing the valve plunger
into the open position.
A relief valve in the governor casing allows
the pump discharge pressure to be relieved if it
exceeds a given set value.
c. F-M mechanical type overspeed governor. The mechanical type overspeed governor
consists essentially of a single weight and a
spring. The spring is adjusted with shims to prevent the weight from moving until the maximum
safe engine speed is reached. When this occurs,
centrifugal forces overcomes spring pressure,
and the weight moves outward, forcing the
overspeed governor lever and its rod downward.
This motion trips the overspeed governor latch
and permits the plunger spring to force the
plunger rod against the fuel cutout lever. This
lever then moves the fuel control arm to the
no fuel position, stopping the engine.
10C3. F-M manual emergency stop and reset lever. The injection of fuel can be stopped
by means of the emergency stop push button
which extends through the control end cover
near the reset lever. The button acts through
linkage and the emergency stop shaft cam to
depress the latch roller (Figure 10-22) and
thus trip the overspeed governor latch. The result is the same as that obtained by moving the
control shaft lever to the STOP position, thus
causing the fuel cutout cam on the control shaft
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Figure 10-23. F-M control shaft and control mechanism.
to move the injection pump control rod to the
no fuel position.
When the engine has been stopped, either
by the emergency stop or the overspeed governor, it cannot be started again until the over
speed stop plunger has been returned to its
normal spring-load position. This is accomplished by moving the reset lever in the direction indicated on the name plate.
10C4. Remote control engine stop. a. Fairbanks-Morse. The engine can be stopped
pneumatically from the maneuvering room. Operation of the remote control lever at that
station permits compressed air to enter a cylinder at the emergency stop mechanism on the
engine. The air moves the stop plunger, thereby
performing the same function as though the
plunger had been moved manually by means of
the emergency stop push button.
b. General Motors. In this installation an
air cylinder operated from the maneuvering
room operates the hand control lever on the
engine. The air cylinder piston is connected to
the hand control lever shaft through a slotted
link and a lever. The compressed air power
stroke moves the lever to the STOP position.
A spring returns the air cylinder piston to the
idling position when the air is shut off and the
line vented. The slotted link allows the hand
control lever to be moved through the full
length of quadrant travel once the air has been
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Copyright (C) 2004-2005 Maritime Park Association
All Rights Reserved
Version 1.11, 27 July 05