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10
GOVERNORS AND ENGINE CONTROLS
 
A. GENERAL
 
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 developed.

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.
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.
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 10-3. Governor cross section-normal speed, steady load.
 
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Figure 10-4. Governor cross section-increased speed, decreased 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 10-5. Governor cross section-normal speed, decreased load.
 
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Figure 10-6. Governor cross section-normal speed, new 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 governor.

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 10-7. Governor cross section-decreased speed, increased load.
 
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Figure 10-8. Governor cross section-normal speed, increased load.
Figure 10-8. Governor cross section-normal speed, increased load.
 
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Figure 10-9. Governor cross section-normal speed, new load.
Figure 10-9. Governor cross section-normal speed, new load.
 
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Figure 10-10. Governor-sections through adapter, power, case, power cylinder and rotating sleeve assembly.
Figure 10-10. Governor-sections through adapter, power, case, power cylinder and rotating sleeve assembly.
 
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Figure 10-11. Governor-section through speed control column.
Figure 10-11. Governor-section through speed control column.
 
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Figure 10-12. Governor-section through accumulator cylinder.
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

  compensating plunger.

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 10-13. Governor-rotating sleeve assembly.
 
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Figure 10-14. Governor-speed control mechanism.
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 movement.

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 as follows:

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 reason.

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 upward.

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 valve bushing.

The regulating port should be completely

Figure 10-15. Governor-measurement
of precompression.
Figure 10-15. Governor-measurement of precompression.

  uncovered for both inner and outer positions of the ballarms.

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.
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 adjusting plug.

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 parts.

Note whether the engine speed, as shown by the tachometer, corresponds to that shown on the governor dial. If not, recheck the speed limit adjustment.

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.
Figure 10-17. Governor control cabinet.

 
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Figure 10-18. F-M governor drive.
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 tachometer indicators.

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 10-19. Governor and tachometer drive, GM.
 
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Figure 10-20. GM hydraulic Type overspeed governor.
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 this assembly.

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 transmit power.

Figure 10-21. GM overspeed shutdown Servo motor.
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.
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.
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 discharged.

 
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