The Diesel-electric switching locomotive has a Diesel engine which drives an electrical generator to supply electricity to four traction motors. The motors are geared to the axles to move the locomotive. Various controls and auxiliary equipment are provided as described further in this manual.
Switching locomotives built by the Electro-Motive Division of General Motors Corporation are built in two sizes or types:
The production of switching locomotives was suspended between April 1, 1943, and January 1, 1945, by government orders which directed Electro-Motive to concentrate on Diesel freight locomotives. During the interim, changes and improvements were made. in the design of the engine and other parts of the locomotive. Where these changes affect the handling or operation of the locomotive, they will be covered in this manual. For this purpose, locomotives built between February, 1939, and April, 1943, are designated as " earlier locomotives, " and those built after January, 1945, as "later locomotives."
Locomotives built prior to February, 1939, were equipped with Model 201A Diesel Engines and are not specifically covered in this manual. The construction and operation of these locomotives are similar in many respects and this, manual maybe used for general instruction.
The engines in all switchers are two-cycle, solid injection type, with cylinders 8-1" bore by lo" stroke, 2 arranged in banks at 45-degree angle. The engines in earlier locomotives were designated 6-567 (600 HP) and 12-567 (1000 HP). On switchers built in 1945 and later, the respective engines are 6-567A and 12-567A. The engines are basically the same in operation except for such differences noted later in the manual.
Diagrams of the engines are shown in Figure 6. Note that the front of the engine is toward the front of the locomotive. The front end of the engine is also called the "accessory end," since the water pumps, lubricating oil Pumps., governor, etc., are located at that end. The diagram can be used to identify the various cylinders by number in making work reports.
The engine is started by using the main generator as a starting motor. Current from storage batteries is utilized, causing the main generator to rotate the Diesel engine.
See Charts I and II for schematic illustration of the fuel oil system of the 600 HP and 1000 HP locomotives, late model. Differences in the fuel oil systems of other locomotives are pointed out below.
Fuel oil is drawn from the storage tank under the locomotive and passes through a suction filter to the motor driven fuel pump. The suction filters on the earlier locomotives are Purolator type, having a handle which should be turned periodically to clean the filter. Later locomotive have wastex or screen filters which require no attention by the enginemen. The fuel pumps are. located. at the left-hand side of the engine compartment, near the front end of the engine. An emergency fuel cuts off is provided in the line between the tank and the suction fuel filter, as described under "Locomotive Protective. Devices."
The fuel pump delivers the fuel to the first discharge fuel filter. On earlier locomotives, the Nugent filter is used. It consists of two filter elements with a handle by which the flow may be directed through either element. Later locomotives have Ful-flo filters with no control handle. After passing through the Nugent or Ful-flo filters, the fuel enters a second discharge filter. This filter contains two sintered bronze elements with a control handle. The sintered bronze filter is used on all models except some early 600 HP locomotives on which "finger strainers" were used.
Normally, the control handles of the filters need not be changed except under circumstances outlined in Section 4 when difficulty is encountered.
After leaving the sintered bronze filter, the fuel passes through manifolds along each cylinder bank. Branches go to the injectors in each cylinder head where small sintered bronze filters provide final protection for the injectors. Excess fuel, not used by the injector, returns to the fuel tank through a fuel return manifold and a relief valve set at 5 lbs. pressure. A relief valve is provided, set at 60 lbs, which bypasses the fuel back to the tank if either or both of the discharge filters become clogged.
Two pressure gauges connected to the fuel lines are used to check the condition of the filters as described in Section 4. A third pressure gauge is connected to the return flow pipe from the injectors. This gauge is located in the cab and indicates whether the engine is getting sufficient fuel. Two direct reading sight level gauges are located at each side of the fuel tank. The upper gauge located in the fuel tank filler casting indicates the fuel level from a full tank down to approximately 4" below the full mark on the gauge, and is used while filling the fuel tank to prevent overflowing. The lower gauge indicates fuel level approximately 4" or less above the bottom of the tank. When this glass is full, 150 or more gallons of fuel remain in tank.
NOTE: Keep open flames away when refueling.
See Charts M and IV for the schematic diagrams of the flow of lubricating oil in the 600 HP and 1000 HP switchers. The illustrations cover later type locomotives using 567A engines with wet sump operation.
Oil is drawn from the oil pan of the engine by the scavenging pump and forced through the oil cooler and lube oil filters to the oil tank strainer chamber. The oil then passes through the suction strainers and goes to the pressure pump, which consists of two pumps in one housing. One section forces oil to the main bearings, gear train, blowers, etc. The second section supplies oil under pressure to cool the pistons. Gauges are provided in the cab which show the pressures of lubricating and piston cooling oil - see Section 2.
The foregoing description covers "wet sump" engines. Some of the earlier locomotives have engines of the dry sump type where the oil reservoir is a separate oil tank rather than the engine oil pan. The oil level gauge or "dipstick" is found on the oil pan of the wet sump engine, while the dry sump engines have the dipstick in the oil tank. A number of these engines have been converted to wet sump operation.
In case of failure of the lubricating oil system, the engine will shut down to idle speed as described under "Locomotive Protective Devices."
Charts III and IV also contain schematic diagrams of the engine cooling systems of the late model 600 HP and 1000 HP locomotives.
Water from the water tank is pumped through the engine cooling water passages in the engine to the radiators at the front of the locomotive, where it is cooled and returned to the water tank.
Two cooling fans are located directly behind the shutters. The fans are Vee belt-driven through sheaves and jackshafts and their speed is proportional to the speed of the engine.
The temperature of the water leaving the engine is shown by a temperature puge in the cab. Earlier locomotives have two gauges, one being connected to the outlet of each cylinder bank, while later models have but one puge in the cab.
The temperature of the engine cooling water is controlled by radiator shutters. On the early Switchers these are operated by a lever in the cab. Automatically controlled shutters are furnished on the latest Switchers. See Section 3 for normal operating temperatures.
The cab heaters are part of the engine cooling water system as water from engine banks passes through them. For operation of cab heater controls, see Section 2.
The cooling system of the engine is filled either through the filler pipe located on the roof of the locomotive above the water tank, or through the side filler pipe located underneath the locomotive frame, to the left front of the fuel tank. This filler pipe can be identified by a cone-shaped fitting on the end of the pipe. When filling the system, the engine is stopped, the "G" valve opened and water added until it runs out the "'G" valve drain. See Section 4, "Low Water Level."
In colder weather, during a layover, the engine cooling system may be heated by steam from an outside source. A connection is provided for such steam supply. If heating is not available and the locomotive must be drained, refer to Charts III and IV which show the drain valves. Also see "Freezing Weather Precautions," Section 3.
For schematic wiring diagrams of the electrical systems of the late model 600 HP and 1000 HP locomotives see Chart VI. To assist in tracing the circuits described below, a table of electrical symbols is given in Chart V.
The Diesel engine drives the main generator which produces direct current electricity for operation of the traction motors. The voltage of the main generator is nominally 600 volts, but varies with the conditions of operation of the locomotive. The Diesel engine also drives an auxiliary generator, through belts, which produces low voltage current (approximately 74 volts) for various purposes such as charging the storage battery, operating the control circuits, lighting, etc.
The current from the main generator flows to four traction motors, two mounted on each truck. The motors are connected in series for low speed and heavy traction operations or in series-parallel for higher speed operation. In series, the current passes through each motor in turn before returning to the main generator, as illustrated in Fig. 7.
In series-parallel, the current from the main generator divides and follows two paths. Each branch consists of two traction motors in series. The current paths then reunite and return to the main generator. The diagram in Fig. 8 shows the current flow when the motors are connected in series-parallel. On 600 HP switchers, (before Serial #4582), the motors are operated in series, at all times, and no provision is made for series-parallel hookup. On 1000 HP locomotives, the traction motors are cooled by blowers, one for each truck. The blowers are belt-driven and turn at approximately three times the speed of the Diesel engine. The blower supplying the two motors of the rear truck is located under the right side of the cab floor. The. 600 Hp locomotives have no traction motor blowers, but some early traction motors had. an impeller type fan attached to the motor shaft.
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| Traction Motor Connections Series Operation Fig.7 | Traction Motor Connections Series-Parallel Operation Fig.8 |
On 1000 HP locomotives, the electrical equipment (contactors, fuses, instruments, etc.) is divided between two cabinets. The high voltage cabinet is located in the forward part of the cab and contains the equipment shown in Fig. 9. The low voltage cabinet, Figs. 10 and 11, serves as the fireman's seat box.
In 600 HP locomotives, both low and high voltage equipment are contained in a single electrical cabinet at the forward end of the cab. Fig. 12 shows the arrangement of this cabinet. In this manual, references are made to certain equipment being located in the low voltage cabinet. On 600 HP locomotives, the items will be found in the electrical cabinet.
| * 1. | VT Relay | 
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|---|---|---|
| 2. | Battery Field Contactor | |
| 3. | Generator Shunt Field Contactor | |
| 4. | Reverser Current Relay | |
| 5. | Main Battery Switch | |
| 6. | Wheel Slip Relay | |
| 7. | VI Voltage Relay | |
| 8. | Ground Protection Relay | |
| *9. | Motor Cutout Switchers | |
| 10. | Ground Relay Cutoff Switch | |
| 11. | Power Contactor, P1-S-P2 | |
| 12. | Battery Charging Contactor | |
| 13. | Engine Starting Contactor | |
| 14. | Voltage Regulator | |
| 15. | Reverser | |
| *16. | Current Limit Relay | |
| 17. | Generator Shunt Field Resistor | |
| 18. | Battery Charging Resistor | |
| 19. | Battery Field Resistor | |
| 20. | Voltage Relay Resistor | |
| 21. | Wheel Slip Resistor |
* 1000 HP Only
| 1. | Battery Charging Ammeter Shunt | 
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|---|---|---|
| 2. | Generator Shunt Field Discharge Resistor | |
| 3. | Generator Shunt Field Contactor Resistor | |
| 4. | Battery Field Discharge Resistor | |
| 5. | Power Contactors, P2-S-P1 | |
| 6. | Reverser |
The change-over from series hookup to series-parallel, or vice versa, is called "transition." It is accomplished by opening and closing of "power contactors" designated "P1", "P2", and "S"- in Figs. 7 and 8 above and so marked in the high voltage cabinet, Fig. 9. It will be noted that, In series arrangement, "P1" and "P2" are open while "S" is closed. In series-parallel, "P1" and "P2" are closed and "S" is open. The operation and control of the power contactors will be covered later.
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| 1 | Voltage Regulator | 
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| 2 | Battery Charging Ammeter | |
| 3 | Resistors | |
| 4 | Rear of Distribution Panel |
| 1 | Main Battery Switch | 
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| 2 | Reverse Current Relay | |
| 3 | Battery Charging Contactor | |
| 4 | Starting Fuse | |
| 5 | Auxiliary Generator Output Fuse | |
| 6 | Battery Field Fuse | |
| 7 | Positive Fuse | |
| 8 | Auxiliary Generator Field Fuse |
NOTE: Power Contactors (P1, S, P2) Not illustrated. | 
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Reversing of the traction motors for forward and back-up operations is accomplished by changing the direction of the current flow through the field windings of the traction motors. The flow through the armature (revolving portion) of the motor remains the same. The reversal of the field current flow is made by a switch called the reverser, controlled by movement of the. engineer's reverse lever. Operation of the reverser will be covered later.
Electricity for the locomotive control, lighting, etc., comes from either of two sources, the storage battery or the auxiliary generator. The storage battery supplies current for lighting while the engine is stopped. The battery also supplies the current necessary for starting, the engine, as described under Engine Starting Circuits. With the engine running, the auxiliary generator keeps the battery charged and supplies the low voltage current demands. Should the auxiliary generator supply fail for any reason, the storage battery will supply demands of the low voltage system and allow operation of the locomotive to continue for a limited time.
The storage battery consists of 32 cells and is connected to, the low voltage system by the Main Battery Switch located in the low voltage cabinet under the fireman's seat, Fig. 11, on the 1000 HP locomotives or in the electrical cabinet, Fig. 12, on 600 HP locomotives. This switch is kept closed at all times when the locomotive is in operation.
The auxiliary generator is belt-driven from the main generator. The supply from this source is regulated and controlled by the equipment listed below, also contained in the low voltage cabinet of 1000 HP locomotives or the electrical cabinet of 600 HP locomotives, Figs. 10 11 and 12.
Regulates the auxiliary generator output voltage, keeping it approximately constant.
Causes the battery charging contactor to open when the output voltage of the auxiliary generator falls to a point just below the battery voltage, preventing a reverse flow of current from the battery to the auxiliary generator.
An electrically operated switch which, when closed, connects the auxiliary generator to the low voltage system. When the auxiliary generator voltage drops for any reason (such as stopping the engine), the battery charging contactor opens, due to the function of the reverse current relay. The battery charging contactor and reverse current relay are necessary to prevent a current from the battery from flowing back through the auxiliary generator when the engine is stopped. This would result in very high current being circulated through the auxiliary generator as well as discharging the battery.
Protects the auxiliary generator and its discharge circuit against excessive load. A blown auxiliary generator output fuse will cut out the auxiliary generator.
Protects the auxiliary generator field windings against excessive current. Blowing of this fuse will also prevent the auxiliary generator from functioning.
The ammeter shows whether the battery is charging or discharging. The ammeter should show zero or a slight "charge " at all times when the engine is running. The amperage will depend on a number of circumstances, and no definite figure can be stated.
On earlier 600 HP and 1000 HP switchers, a voltmeter shows the output voltage of the auxiliary generator.
When the "Engine Start" button is pressed, a circuit is completed which energizes the operating coils of the starting contactors (ST- and ST+), causing these contactors to close. With the starting contactors closed, current from the storage battery flows through the main battery switch to the armature and starting field windings of the main generator. This causes the main generator to act as a motor to crank the Diesel engine. A 400-ampere fuse is included in the starting circuit.
The control circuits of the locomotive perform the following functions:
The throttle must be opened at least 1/2 " from idle position or enough to close throttle switch in control stand, the reverse lever in forward or reverse, and the control and generator field push-button switches closed, to establish the circuit which closes the battery and shunt field contactors.
Opening the generator shunt field and generator battery field contactors causes the power output of the main generator to decrease. The time delay relay (VT) does not close instantly when the transition relay closes. It delays closing about one-fifth of a second, to allow time for the main generator current to decrease before transition takes place. Closing of the time delay relay establishes the circuit which energizes the magnet valve of the "PI" contactor, causing th e contactor to close. As this contactor moves to closed position, its mechanism opens an interlock which breaks the circuit energizing the magnet valve. of the "S" contactor, causing it to open. When "S" contactor opens, its mechanism closes an interlock which establishes a circuit to energize magnet valve of "P2" contactor, closing it. Completion of the sequence causes the shunt field and battery field contactors to close and the main generator to resume production of power.
The sequence for automatic transition on the 600 HP is the same as, for the 1000 HP locomotive except that no time delay relay (VT) is used. The transition relay completes the circuit to close the P1 contactor as soon as the Battery Field (BF) drops out.
For transition from series-parallel back to series, it is necessary to close the throttle to idle. When the throttle is returned to idle, the movement of the lever opens a switch in the control stand which breaks the circuits, de-energizing the "'P1" and "P2" contactor magnet valves. When these contactors open the movement of "P1" closes the circuit to close "S" contactor. Thus the power circuits are again in series arrangement. It is also possible to effect transition from series-parallel to series by pushing the selective transition switch to "IN-SERIES" position. This practice is not recommended.
The main generator contains five field windings - starting, differential, commutating, battery field, and shunt field. The first is used only when the main generator acts as a starting motor. The second and third are permanently connected and a matter of engineering design of the generator. The last two are of interest since they govern the power output of the main generator. The battery field of the main generator is excited by low, voltage current supplied by the battery or the auxiliary generator. The current passes through the battery field contactor (BF), covered under "Control Circuits," and the load regulator.
The load regulator is a device which loads the engine according to the throttle setting in the cab. It automatically maintains a constant horsepower output corresponding to each throttle position within effective limits.
For the purpose of load regulation the means of determining the horsepower output of the engine is based on the rate of fuel consumption. This is determined by the relationship between the speed setting on the governor and the position of the power piston controlling the opening of the injector racks. If the engine demands more fuel than a predetermined setting or balance point, the load regulator reduces the load on the engine by reducing the field excitation of the main generator, thereby reducing its power output.
If the engine requires less fuel than the predetermined setting, the load regulator increases the load on the engine by increasing field excitation of the main generator. In this manner, battery voltage, temperature causes in generator windings, or locomotive speeds do not cause overloading or underloading of the engine.
The load regulator has two components: first, the Pilot valve (attached to the governor on early models and incorporated in the governor on late models), and second, a self-contained unit which consists of an hydraulic rotary vane type motor attached to the commutator type rheostat. The shunt field is connected across the armature of the generator. When the armature turns and builds up voltage, current flows through the shunt field. The circuit is provided with a shunt field contactor (SH) which must be closed, as described under "Control Circuits," to establish the circuit and make the shunt field effective.
The fuel pump motor is operated by low voltage current supplied through the fuel pump switch and 15- ampere fuse in the control push-button box.
The purpose and operation of the wheel slip relay (WSR) are explained under "Wheel Slip Indicator " later in this Section. When the relay picks up on later locomotives. It closes a circuit which allows the shunt field contactor operating current to by-pass the contactor operating coil. This de-energizes the shunt field contactor (SH) operating coil and opens the contactor. When the shunt field contactor opens, it causes the battery field contactor (BP) to open. On earlier locomotives, the wheel slip relay is normally closed when the wheels SIIP, the relay opens and breaks the circuit which keeps the shunt field contactor closed. The contactor opens and, in turn, causes the battery field contactor to open.
Current for the lighting circuits of the locomotive is supplied through the various switches on the light push-button switch box. Each switch has a corresponding fuse. The operation of the headlight switch is explained in Section 3. Engine compartment lights and plug receptacles are also provided with a 15-ampere fuse in the former and 10-ampere fuse in the later. These fuses are located in the voltage cabinet. Blowing of the 15-ampere fuse will also prevent operation of the wheel slip indicator light.
This relay is connected in series with the main generator. It picks up when the main generator current reaches an overload figure. When "picked up,"' it causes the wheel slip light to burn steady and indicates that backward transition should be made from series-parallel to series. See "Wheel Slip Indicator" under "Locomotive Protective Devices."
Switches (MC01 and MC02) are, provided in the high voltage cabinet by which the power may be cut off on either truck as desired. This feature is provided to assist in retailing the locomotive after a derailment (see Section 4) or to enable the locomotive to proceed to the maintenance point in case of traction motor trouble in one truck. The locomotive must not be worked in yard or transfer service with one truck cut out.
A schematic diagram of the air system is given in Fig. 13. The side view of the air compressor is shown in Fig. 14.
The locomotive is equipped with a Gardner-Denver 3-cylinder, two-stage, type WXE air compressor, which is driven by the crankshaft of the Diesel engine through a flexible coupling. The compressor has its own oil pump and pressure lubricating system. Oil level in the crankcase can be checked out the bayonet type puge - located on the left side of the compressor. The oil level In the compressor crankcase can be accurately checked only when the engine is stopped. With hot oil, lubricating oil pressure should be from 12 to 15 pounds at 800 RPM and not less than 5 pounds at idle.
The compressor is equipped with an unloading device which to operated by a governor connected to the main reservoir. When main reservoir pressure reaches 130 pounds, the governor actuates the unloader which holds the intake valves open in the compressor preventing it from pumping air. When the main reservoir pressure to 120 pounds, the governor cuts off the air supply falls, to the unloader and the compressor resumes delivery of air.
The control air pressure is taken from the main air reservoir through a reducing valve, located in the cab under the right-hand cab window. The valve is adjusted to a pressure of 80 pounds, which is used to operate the reverser and main power contactors. The control air gauge is located on the right side of the high voltage cabinet, and should this gauge show main reservoir air pressure, it is an indication that the reducing valve is stuck open. There is no harm in operating the locomotive temporarily with the control air gauge showing main reservoir air pressure, but it should be reported to the maintenance point as soon as possible.
The ground protective relay is located in the high voltage cabinet. If a ground occurs in the high voltage system, the ground protective relay will trip and cause the shunt field contactor and battery field contactors to open. The locomotive will lose all power and come to a stop. In case of a ground in the low voltage circuits, the ground protective relay will trip when the engine is started. For action in case of a tripped ground protective relay, see Section 4.
If the engine runs overspeed, a trip operates to shut the engine down. The engine speed at which this will occur is approximately 100 to 110 RPM over the rated maximum speed of 800 RPM. Overspeed trip operation may be caused by sudden loss of electrical load, such s wheel slippage or ground protective relay (GR) tripping.
The overspeed trip resetting lever is located on the front end of the engine directly behind the engine governor. To reset the overspeed trip, the lever is pulled in a counterclockwise direction, as indicated by the arrow Painted on the engine.
While termed a "shutdown cylinder," this device does not stop the engine. It reduces and holds the engine speed to idle in the event of trouble in the lubricating oil system. Opening the locomotive throttle will not speed up the engine under these circumstances. It consists of a cylinder containing a spring loaded piston which is connected to the throttle linkage, as shown in Fig. 15,. Lubricating oil pressure acts on one side of this piston, moving it against the action of the spring.
On earlier locomotives, any failure of lubricating oil pressure allows the spring to force the piston back and so bring the engine to idle speed. An electrically operated magnet move or oil escape valve is also connected to the cylinder. If the piston cooling oil pressure. drops below a safe limit, a pressure operated switch opens the oil magnet valve allowing the oil to escape from the cylinder. The spring moves the piston and brings the engine to idle speed. On later locomotives, a similar escape valve is provided which is operated somewhat differently. If the main bearing oil pressure drops below a safe limit, a pressure operated switch (low oil pressure switch - LOP) closes the circuit which energizes the oil magnet valve, allowing the oil in the cylinder to escape. Should the vacuum in the suction pipe of the oil pump become excessive, due to clogged suction strainer screens a second switch (lube oil suction switch - LOS) will close and energize the same oil magnet valve. For locomotives built after January 1, 1948, see Lubricating Oil System, Section 1, Page 104.
This valve is located in the fuel suction line between the sump and the fuel pump. In the event of fire, the valve can be closed by pulling any one of three pull rings which are connected by cable to the fuel cutoff valve. One pull-ring is located in the cab on the side of the controller; the other two are located on each side of the locomotive near the fuel filler casting in a small red box with lift cover. The boxes are attached to the locomotive underframe.
If the fuel cutoff valve is closed, it must be reset to the "open" position by hand.
1. When wheel slipping occurs, wheel slip relay (WSR) in the electrical control cabinet will pick up. This will light the wheel slip indicator on the engineer's Instrument panel in the cab and will open the shunt field contactor (SH) and battery field contactor (BF) in the electrical control cabinet. The power output of the main generator will thus be reduced and the traction motor torque will drop, stopping the slipping. When the slipping stops, the wheel slip relay will drop out. This will cause the battery field contactor and shunt field contactor to close, restoring the power output of the main generator and the traction motor torque. Generally, wheel slipping intermittent, about once per second.
If one pair of wheels is locked, due to a broken pinion or axle gear, or the armature shaft is "frozen" in its bearings, the wheel slip indicator will light and stay on as long as current is being supplied to the motors and the other motor in the truck is turning.
The wheel slip indicator will operate during either series or series-parallel operation. 2. On 1000 HP locomotives only, the wheel slip light has a second function. When the current in the generator rises to the point where transition should be made back to series, the current limiting relay (CLR) will light the wheel slip light causing it to burn continuously. When the current limiting relay operates the wheel slip indicator light, the traction motors should be returned to series operation immediately.
The engines on locomotives delivered after Jan. 1, 1948, are equipped with a Woodward Governor which includes a pneumatic-hydraulie governor speed control, or an electro-hydraulic control on units equipped for multiple unit operation.
In case of low oil pressure or high vacuum on the suction side of the lube oil and piston cooling oil pumps, the engine governor will stop the engine.
When the governor safety control stops the engine, a push-button on the front of the governor housing moves out approximately 3/8" exposing a red band around the shaft of the button. On these locomotives, the engine shutdown lever is omitted and a "Stop" position included in the throttle. "Stop" obtained by pressing the button on the end of the throttle lever and moving the throttle past "Idled" to "Stop" position.
The push-button will not trip if the engine stops due to placing of throttle in emergency "Stop" position, operation of manual layshaft control lever, tripping of ground protective relay when throttle is in Run 5 or Run 6 or use of the "STOP" button for normal shutdown.
When the engine is stopped by governor control action, the push-button must be reset before the engine can be started. When the engine is started and run at idling speed, the governor will stop the engine again after approximately 40 seconds, if the condition still exists which caused the original shutdown. This time delay is provided to allow a check to determine the cause of the shutdown. However, if an attempt is made to run the engine above idling speed during the delay period, the governor will stop the engine at once should the oil pressure be low or the oil pump suction be high.