Usage:
General Information
The 1140, 1145, 1150, and 1160 are direct injection, 4 stroke cycle, 90° V8, diesel engines. All use the same basic head and block [4.5 in. (114.30 mm) bore] but vary rpm, stroke and fuel systems to produce four different horsepower ratings. The oil pan and flywheel configurations depend upon engine application. The cylinders are numbered from the front with the odd numbers, 1, 3, 5 and 7 located in the right bank (as viewed from the flywheel). The firing order is 1, 2, 7, 3, 4, 5, 6, 8. The dry weight of the engines, with accessories, is approximately 1200 lbs. (544.3 kg).
A plunger and barrel type fuel injection pump located in the vee, meters and pumps fuel under high pressure to the injection nozzles. The injection pumps are two sizes. The 1160 Engine uses 9.0 mm pumps, while the others use 8.5 mm pumps. A timing advance unit advances the fuel injection timing as speed increases.
Earlier engines utilize the max-min type of governor, mounted on the rear of the fuel injection pump housing. The max-min governor controls the fuel rack automatically at or above the full load rpm and below approximately 900 rpm. Between these speeds, the fuel rack is controlled directly by the accelerator linkage. Later engines have a hydraulic governor that maintains full range control of the fuel rack.
The engines are of the overhead valve design and have one intake and one exhaust valve per cylinder. The camshaft, geared and timed to the crankshaft, actuates rocker arms and valves through mechanical lifters and push rods. There is a single rocker arm shaft for each head. The shaft is mounted in an aluminum support which spaces the rocker arms. The entire guide, shaft and arm assembly can be removed and installed as a unit.
The lubrication system contains an eccentric six lobe oil pump. The pump is housed in the timing gear cover.
The cooling system contains a belt driven centrifugal pump. Two thermostats on the inlet side of the water pump regulate engine coolant temperature.
The crankshaft pulley and vibration damper are integral units on the 1150 and 1160 Engines. The 1140 and 1145 Engine do not use the vibration dampers.
Fuel System
The fuel system consists of the transfer pump, fuel filter, shutoff solenoid, injection pumps, timing advance unit, governor, injection lines, nozzles and excess fuel return lines.
The diaphragm type fuel transfer pump mounts on the fuel injection pump housing and is driven by a lobe on the injection pump camshaft. The pump draws fuel from the vehicle supply tank and delivers it to a spin on throw away type filter. The filter is a combination primary-secondary element.
Filtered fuel flows through a fuel shutoff solenoid, mounted on the fuel injection pump housing, into a fuel manifold. The solenoid operates electrically and stops fuel flow when the vehicle ignition system is off.
Fuel in the manifold flows through the barrel assembly inlet port into the area above the injection pump plunger. During injection, the camshaft forces the plunger upward in the barrel. The end of the plunger closes the inlet port and forces the fuel out through high pressure injection lines to the nozzles.
The injection nozzles are located under the valve cover and are held in place by clamps. The nozzle tip projects from the head into the cylinder bore. Atomized fuel is sprayed in a cone shaped pattern through four .0128 in. (0.325 mm) orifices into the cylinder.
During injection, a small amount of fuel leaks past the valve guide in the nozzle body to lubricate its moving parts. Any excess leakage flows from the nozzle to a fuel return manifold under the valve cover of each cylinder head. External lines connect the manifolds and return the fuel to the tank.
Governor Operation
9L7800 Governor
The hydraulic governor maintains speed at the rpm selected.
When the engine is operating, the balance between the centrifugal force of revolving weights (3) and the force of the governor spring assembly (2) controls the movement of valve (4). Valve (4) directs pressure oil to either side of rack-positioning piston (8). Depending upon the position of valve (4), the rack is moved to increase or decrease the amount of fuel to the engine to compensate for load variation.
Pressurized lubrication oil, directed through passages in the fuel injection pump housing, enters a passage in governor cylinder (5). The oil encircles a sleeve (9) within the cylinder (5). This oil is then directed through a passage in piston (8) where it contacts valve (4).
GOVERNOR
1. Low idle screw. 2. Governor spring assembly. 3. Weights. 4. Valve. 5. Cylinder. 6. High idle spring. 7. Low idle spring. 8. Piston. 9. Sleeve.
When engine load increases, revolving weights (3) slow down. Weights (3) move toward each other and allow governor spring assembly (2) to move valve (4) forward. As valve (4) moves, a small passage in piston (8) opens to pressure oil. Oil flows through this passage and fills the chamber behind piston (8). The pressure forces piston (8) and rack forward, increasing the amount of fuel to the engine. Engine rpm increases until revolving weights (3) rotate fast enough to balance the force of governor spring assembly (2).
When engine load decreases, revolving weights (3) speed up and the toes on weights (3) move valve (4) rearward, allowing oil behind piston (8) to flow through a drain passage opened at the rear of the piston. At the same time, pressure oil between sleeve (9) and piston (8) forces piston (8) and rack rearward. This decreases the amount of fuel to the engine and the engine slows down. When the force of revolving weights (3) is in balance with the force of governor spring assembly (2), engine rpm will be the same as before.
At engine shut down, low idle spring (7) returns piston (8) and valve (4) to the fuel on position. This moves the rack to fuel on position. Piston (10) moves forward covering oil supply hole (12) compressing spring (11) and forces the oil in the chamber in front of piston (10) to drain through bleed orifice (13). This permits approximately the same rack travel as the earlier governors that do not use piston (10) and spring (11) and assures full fuel delivery at engine start-up.
After the engine starts and governor weights (3) begin to control engine speed, spring (11) moves piston (10) to the rear and opens oil passage (12). Oil under pressure enters through oil passage (12) and prevents the forward movement of piston (10). This will limit the travel of the fuel rack to slightly more than is necessary for full load operation.
PISTON IN START-UP POSITION
10. Piston. 11. Spring. 12. Oil passage. 13. Bleed orifice.
PISTON IN RUN POSITION
10. Piston. 11. Spring. 12. Oil passage. 13. Bleed orifice.
Governor spring assembly (2) allows for governor regulation between low idle and full load operation. High idle spring (6) allows for governor regulation when operating at full load.
9L9540 Governor
The hydraulic governor maintains speed at the rpm selected.
When the engine is operating, the balance between the centrifugal force of revolving weights (2) and the force of governor spring assembly (1) controls the movement of valve (3). Valve (3) directs pressure oil to either side of rack-positioning piston (7). Depending upon the position of valve (3), the rack is moved to increase or decrease the amount of fuel to the engine to compensate for load variation.
Pressurized lubrication oil, directed through passages in the fuel injection pump housing, enters a passage in governor cylinder (4). The oil encircles sleeve (8) within cylinder (4). This oil is then directed through a passage in piston (7) where it contacts valve (3).
GOVERNOR
1. Governor spring assembly. 2. Weights. 3. Valve. 4. Cylinder. 5. High idle spring. 6. Low idle spring. 7. Piston. 8. Sleeve.
When engine load increases, revolving weights (2) slow down. Weights (2) move toward each other and allow governor spring assembly (1) to move valve (3) forward. As valve (3) moves, a small passage in piston (7) opens to pressure oil. Oil flows through this passage and fills the chamber behind piston (7). The pressure forces piston (7) and rack forward, increasing the amount of fuel to the engine. Engine rpm increases until revolving weights (2) rotate fast enough to balance the force of governor spring assembly (1).
When engine load decreases, revolving weights (2) speed up and the toes on weights (2) move valve (3) rearward, allowing oil behind piston (7) to flow through a drain passage opened at the rear of the piston. At the same time, pressure oil between sleeve (8) and piston (7) forces piston (7) and rack rearward. This decreases the amount of fuel to the engine and the engine slows down. When the force of revolving weights (2) is in balance with the force of governor spring assembly (1) engine rpm will be the same as before.
At engine shut down, low idle spring (6) returns the piston (7) and valve (3) to the full load position. This moves the rack to full travel position, and assures full fuel flow through the fuel injection pump at engine start-up.
Governor spring assembly (1) allows for governor regulation between low idle and full load operation. High idle spring (5) allows for governor regulation when operating at full load.
Max-Min Governor
The "max-min" type governor mounts on the rear of the fuel injection pump housing. The governor controls the fuel rack automatically at or above rated speed and below approximately 900 rpm. In the range between, the fuel rack is controlled directly by the accelerator linkage.
There are two types of linkage movement within the governor. One type is actuated by external linkage from accelerator movement. The second type is actuated by spring or roller forces within the governor. The rollers sense load changes at or above rated speed and the fuel rack moves accordingly.
Both types of movement utilize the same linkage components within the governor, but in different manners. Linkage from the accelerator fastens to one end of a pivoting link. The other end of the link fastens to linkage connected to the fuel rack. The link is pinned at its center to a yoke and pivots on this point.
Accelerator movement pivots the link around its center point and moves the fuel rack. The maximum amount of rack travel generated by accelerator movement is controlled by limiting the pivot arc of the link. A "power screw", located under the governor rear cover, provides an adjustable stop at one end of the link thereby stopping rack travel at the other.
When the engine is stopped, the rollers are in toward the spindle shaft. The high idle spring forces the collar forward to the housing stop. The low idle spring, contained within the collar, continues to push the yoke forward along the shaft. The yoke and pivot point move to its maximum position toward the pump housing.
When the accelerator is depressed to start the engine, the link pivots on its center point. The combination of the pivoting and the forward position of the pivot point provides the maximum amount of fuel necessary to start the engine. A collar on the fuel rack contacts the pump housing and provides a stop that limits rack travel and excess fuel.
After starting, the rollers begin to force the yoke back against the low idle spring. At approximately 900 rpm, the low idle spring is compressed and the yoke is against the sliding collar. From 900 rpm up to rated speed, roller force is not great enough to move the yoke or fuel rack. Rack movement throughout this range is controlled by the accelerator through the pivoting link. At rated speed, roller force becomes great enough to move the collar and yoke against high idle spring. At high idle, the forces on the sliding yoke are balanced and it is stationary on the spindle shaft.
When the load on the engine increases, engine speed decreases resulting in less centrifugal force generated by the rollers. Spring force moves against the smaller force and pushes the sliding yoke forward along the spindle shaft.
As the yoke slides forward, the link pivots about the end opposite the rack. Link travel at the rack end moves the rack to match the load.
The high and low idle springs push against the yoke through a sliding collar. The collar slides along the shaft and pilots in a bore in the governor housing. The forward movement of the collar and yoke is restricted by a flange on the collar which contacts the governor housing.
A washer and a coned disc torque spring are located around the collar between the flange and the housing. At rated load and speed, the collar is positioned so the torque spring and washer are just touching the housing. Any additional load on the engine causes the high idle spring to move the collar and compress the torque spring against the washer and housing. The extra movement of the collar and yoke provides additional fuel which generates a torque rise to prevent stalling the engine. The governor on the 5.0 in. (127.0 mm) stroke engine does not use a torque spring. Its natural lugging ability provides sufficient torque rise.
As the load on the engine decreases, engine speed and roller force increases. The rollers move away from the spindle shaft thereby forcing the collar and yoke to the rear against the springs. Engine speed stabilizes when roller and spring forces balance and yoke movement stops. If all the load is removed, engine speed stabilizes at high idle. The high idle speed is determined by the force of the high idle spring. The spring force is controlled by the adjusting screw located under the rear cover.
Injection Nozzle Operation
The nozzle is an inward opening, differential hydraulically operated, hole type nozzle.
The nozzle body incorporates the inlet fitting, tip and valve guide. The inward opening valve is spring-loaded. Spring preload is adjusted through the pressure adjusting screw; valve lift is controlled by the adjustable lift screw. Both adjusting screws are secured by the locknut. A nylon compression seal under the inlet fitting "banjo" prevents cylinder compression leakage. The carbon dam at the lower end of the body prevents carbon accumulation in the cylinder head bore.
Fuel, under pressure from the injection pump, flows through the inlet, around the valve, filling the nozzle body. When the pressure acting on the differential area overcomes the spring force, the nozzle valve lifts off its seat. Fuel under high pressure sprays through four .0128 in. (0.325 mm) orifices into the cylinder. When delivery to the nozzle ends and pressure drops to the predetermined closing pressure, the spring returns the valve to its seat.
Positive sealing is maintained by line contact of the interference angle between valve and tip seat.
During injection, a small quantity of fuel leaks through a controlled clearance at the valve guide, lubricating all moving parts. This fuel flows through a bleed boot at the top of the nozzle body and returns to the fuel tank.
9L7883 Nozzles
The nozzle is an inward opening, differential hydraulically operated, hole type nozzle.
The nozzle body incorporates the inlet fitting, tip and valve guide. The inward opening valve is spring-loaded. Spring preload is adjusted by shims under the pressure screw; valve lift is controlled by the adjustable lift screw. The adjustable lift screw is secured by a locknut. A nylon compression seal under the inlet fitting "banjo" prevents cylinder compression leakage. The carbon dam at the lower end of the body prevents carbon accumulation in the cylinder head bore.
FUEL INJECTION NOZZLE
1. Lift adjusting screw. 2. Locknut. 3. Pressure screw. 4. Spring. 5. Spring seat. 6. Valve guide. 7. Fuel inlet. 8. Compression seal. 9. Valve. 10. Orifices (four). 11. Shims. 12. Nozzle body. 13. Carbon dam. 14. Nozzle tip.
Fuel, under pressure from the injection pump, flows through the inlet, around the valve, filling the nozzle body. When the pressure acting on the differential area overcomes the spring force, the nozzle valve lifts off its seat. Fuel under high pressure sprays through four .0128 in. (0.325 mm) orifices into the cylinder. When delivery to the nozzle ends and pressure drops to the predetermined closing pressure, the spring returns the valve to its seat.
Positive sealing is maintained by line contact of the interference angle between valve and tip seat.
During injection, a small quantity of fuel leaks through a controlled clearance at the valve guide, lubricating all moving parts. This fuel flows through a leak off boot at the top of the nozzle body and returns to the fuel tank.
Fuel Injection Pump Operation
Engines Equipped With Hydraulic Governor
The injection pump plungers are moved up into the barrels by the cam lobes. The plungers always make a full stroke. The lifters are held against the cam lobes by spring force applied to the plungers.
Injection begins when the top of the plunger passes and closes the inlet port. The point of injection relates to crankshaft position and is controlled by the lifter assembly thickness. A thicker lifter assembly advances the point of injection and a thinner lifter assembly retards it.
The amount of fuel pumped per stroke is varied by turning the plunger in the barrel. Governor action moves the rack which turns the pump gear segment on the bottom of the plunger.
Engines Equipped With "Max-Min" Governor
The injection pump plungers are moved up into the barrels by the cam lobes. The plungers always make a full stroke. The lifters are held against the cam lobes by spring force applied to the plungers.
Injection begins when the top of the plunger passes and closes the inlet port. The point of injection relates to crankshaft position and is controlled by the timing washer thickness. A thicker washer advances the point of injection and a thinner washer retards it.
The amount of fuel pumped per stroke is varied by turning the plunger in the barrel. Accelerator or governor action moves the rack which turns the pump gear segment on the bottom of the plunger.
Automatic Timing Advance Unit Operation
Fuel Injection Pump Camshaft Mounted
The automatic timing advance unit is geardriven and mounts on the front of the injection pump camshaft. The drive gear connects to the camshaft through spring loaded sliding weights and a carrier. Two guides, secured to the carrier, fit into two angular slots in the weights. As centrifugal force moves the weights outward against spring pressure, the movement of the slots causes the guides to change the angular relationship between the gear and carrier. This relationship is maintained through the carrier and shaft to the pump camshaft, thereby changing injection timing.
The unit functions from approximately low idle up through rated speed. The amount of timing advance is marked on the unit. It is seat at the factory and is not adjustable.
Engine Camshaft Mounted
The automatic timing advance unit mounts on the front of the engine camshaft.
The unit functions from approximately low idle up through rated speed. The amount of timing advance is marked on the unit. It is set at the factory and is not adjustable.
Air Induction And Exhaust System
The air induction and exhaust system consists of the air cleaner, air intake pipe, positive crankcase ventilator, inlet manifolds and exhaust manifolds.
The air inlet system is located on top of the engine. The intake pipe provides for either a dry type or oil bath air cleaner. The pipe directs air to each cylinder head. The pipe cannot be turned end-for-end because the air cleaner mounting flange sets at a slight angle toward the front of the engine.
The inlet manifolds are integrally cast in the cylinder heads. The manifolding, porting and combustion chamber design generates the air turbulence necessary for complete combustion.
The exhaust system is located on each side of the engine. The exhaust manifolds mount along the outside of the cylinder heads and are not interchangeable.
A positive crankcase ventilator mounts on top of the rocker arm cover. The valve vents crankcase fumes back to the engine through the intake pipe. The rocker arm cover on which the valve mounts is interchangeable between banks. However, the ventilator return pipe fitting must be interchanged with a plug in the intake pipe.
Cylinder Head And Valves
CYLINDER HEAD AND VALVES
1. Push rod. 2. Cam follower. 3. Guide support. 4. Rocker arm shaft. 5. Rocker arm. 6. Exhaust valve. 7. Valve seat insert. 8. Intake valve. 9. Inner valve spring. 10. Outer valve spring.
The cylinder heads are interchangeable among the 4.1 in. (104.14 mm), 4.5 in. (114.30 mm), and 5.0 in. (127.00 mm) stroke engines. In addition, the heads can be used on either the right or left bank by installing a core plug in the unused water outlet in the end of the head. The air inlet manifold is cast into the head.
The camshaft actuates the valve mechanism. A drive gear is secured to the end of the camshaft and driven at one half engine speed by the crankshaft gear. Five bearings in the cylinder block support the camshaft. A thrust pin, which locates in a groove in the camshaft adjacent to the rear support bearing, positions the shaft and absorbs any thrust.
Solid type cam followers are located in the cylinder block and follow the cam lobe profile. The push rods transmit the lifting motion to the rocker arms.
The rocker arms mount on the rocker arm shaft. There is a single rocker shaft for each head. The shaft mounts in a support guide which spaces the rocker arms. The entire guide, shaft and rocker arm assemblies can be removed and replaced as a unit. The valve lash must be checked and adjusted, if necessary, after installing the unit.
Each cylinder has one intake and one exhaust valve. The exhaust valve uses a replaceable valve seat insert which is pressed into the cylinder head. The intake valve seat is machined in the head. The air inlet port design above the intake valve seat gives the proper swirl to the incoming air. The valve guide bores are cast integrally and machined in the cylinder head. There are two springs, an inner and outer, per valve. The springs are interchangeable between the intake and exhaust valves.
Lubrication System
The lubrication system consists of the oil pump, cooler, filters, internal passages and the oil pan. The pan can be turned end-for-end to provide either a front or rear sump. The dipstick placement and suction tube length correspond with sump location. A longer suction tube and support is required when the pan is positioned for a rear sump.
Oil moves through the screen and suction tube to the inlet passage in the oil pump cover. The oil pump cover bolts to the back of the engine front cover. The inlet passage directs oil to the pump.
The oil pump is a six lobe, rotor type. The crankshaft gear drives the outer rotor which rotates in a bearing in the front cover. The inner rotor mounts on a stub shaft in the front cover and is driven by the outer rotor.
A bypass valve in the pump cover senses pump outlet pressure. The valve opens at approximately 72 psi (5.1 kg/cm2) and bypasses oil back to the inlet side of the pump.
Oil from the pump flows through a passage in the front cover to the cylinder block and on to the oil cooler base. The base mounts on the left side of the block. A valve in the base bypasses oil around the cooler when the oil is cold or the oil cooler restriction is higher than the rest of the system. A 14 to 22 psi (0.89 to 1.55 kg/cm2) pressure differential opens the valve.
Oil from the cooler flows to two spin on, throw away filters mounted on the oil cooler base. Each filter contains a bypass valve. If the filters become clogged, oil is bypassed around them. An 18 to 20 psi (1.27 to 1.41 kg/cm2) pressure differential opens the valves.
There are three pressure taps in the oil cooler base. Two taps, located on the outlet side of the cooler and filters, are for the oil pressure gauge and a low pressure alarm. One, located on the bypass spring retainer, provides supply oil for an auxiliary filter.
A drilled passage in the block directs oil from the filters to the oil manifold. The oil manifold is in the vee above the camshaft mounting and extends the length of the block. Oil flows from the manifold to the camshaft bearings. There are grooves in the cylinder block bore around the camshaft bearings. The camshaft journals are lubricated from these grooves through a hole in the bearing. The remaining oil flows around the groove and down through a drilled passage to a hole and a groove in the upper half of the main bearings. Oil from the hole and groove lubricates the main bearing journals.
Oil flows into the crankshaft through holes in the main bearing journals. Drilled passages connect each main bearing journal with the adjacent connecting rod journals. The piston pins are splash lubricated.
The rocker arms receive oil from the oil manifold. Drilled passages in the block align with a passage in each of the cylinder heads. The passage to the left cylinder head intersects the oil manifold near the front of the engine. The passage to the right cylinder head intersects near the rear of the engine.
The passage in each cylinder head aligns with a cavity in the underside of the rocker arm support bracket mounting boss. The cavity is in the front on the left bank and in the rear boss on the right bank. Oil flows to the cavity and up through the boss around the bracket mounting bolts, to the center of the rocker arm shaft. Oil flows along the center of the shaft to the rocker arm bearings. A drilled hole in the rocker arm conveys oil from the the bearings toward the ends of the valve stem and push rod sockets. Passages in the head and block drain this oil back to the sump. A second hole in the rocker arm provides pressure oil for the ends of the push rods. Oil drains down along the push rods to lubricate the lifters and camshaft lobes before returning to the sump.
An external line supplies oil to either the vacuum pump or air compressor. The line taps off a passage toward the rear and the vee side of the right cylinder head. An external line drains this oil to the front cover and back to the sump.
The fuel injection pump camshaft bearings are lubricated through a passage from the oil manifold. A hole in the camshaft rear bearing opens into a groove on the inside diameter of the bearing. Oil from the groove flows through a drilled hole in the camshaft rear journal and into the center of the camshaft. Holes from the center of the camshaft intersect the front and intermediate bearing journals and lubricate the bearing surfaces. Oil accumulates in the housing until it reaches the level of an opening in the front face of the pump housing. Oil spills out through the opening to splash lubricate the gears in the front cover.
The "max-min" governor spindle shaft fits into the end of the injection pump camshaft. Oil flows from the camshaft to and along the center of the spindle shaft. A cross drilled hole in the shaft lubricates the governor components. An opening in the rear face of the fuel pump housing maintains the desired oil level in the governor housing. Oil drains through the opening into the injection pump housing and into the cylinder block.
Oil from the engine lubricating system lubricates the hydraulic governor weight bearing. The various other parts are splash lubricated. The oil from the hydraulic governor drains into the fuel injection pump housing.
Cooling System
The centrifugal type water pump mounts on the front cover and is belt driven by the crankshaft pulley. The pump has two outlets. Coolant from the outlet on the right side of the pump flows through a passage in the front cover to the left bank of the engine, and coolant from the outlet on the left flows to the right bank.
The coolant circulates through the block to the cylinder heads. Coolant flows from the heads through connecting sleeves to the return manifold in the front cover. Orifices in the sleeves control the flow from the heads.
Part of the coolant to the left bank is diverted from the block to the oil cooler. External lines direct coolant from the block to the cooler and back to the return manifold in the front cover.
An internal passage in the front cover directs the coolant from the return manifold to the water pump inlet. If the thermostats are closed the coolant flows to the pump and is recirculated through the engine. If they are open, coolant flows from the return manifold to the radiator and from there to the pump.
The radiator is constructed with a top tank above the core and an expansion tank either above or separate from the top tank. A vent tube connects the radiator top tank and the expansion tank. The expansion tank has a shunt line which connects to the water pump inlet. This shunt system maintains a positive, static head of coolant at the pump inlet to prevent cavitation under all operating conditions. When filling the cooling system, coolant from the expansion tank flows through the shunt line to the water pump inlet and fills the engine block from the bottom. By filling the system from the bottom, air in the system is forced out through the top tank, through the vent tube into the expansion tank.
The two thermostats are located at the inlet to the water pump. The inlet-regulated cooling system maintains positive coolant temperature control with decreased engine warm up time.
When the thermostats are closed, coolant is circulated through the block and heads and back to the water pump by way of an internal passage in the front cover. When the thermostats are open, the bypass flow is restricted and the engine coolant flows through the radiator and returns through the inlet elbow to the water pump. Without the thermostats installed, the coolant will continually bypass the radiator, and overheating will result.
Electrical System
Starting Motor
The starting motor is a device used to rotate the flywheel of an engine fast enough to start the engine. A solenoid is used with the starting motor. The action of the solenoid engages the pinion with the ring gear on the engine flywheel when the solenoid is energized. The pinion always engages before the electric contacts in the solenoid close the circuit between the battery and the starting motor.
STARTING MOTOR
1. Field. 2. Solenoid. 3. Clutch. 4. Pinion. 5. Commutator. 6. Brush Assembly. 7. Armature.
An overruning clutch prevents the starting motor from being overspeeded. Releasing the starter switch disengages the pinion from the ring gear of the flywheel. The starting motor is grounded to the engine.
Starter Solenoid
A solenoid is a magnetic switch that utilizes low current to close a high current circuit. The solenoid has an electromagnet with a movable core. There are contacts on the end of the core. The contacts are held open by a spring that pushes the core away from the magnetic center of the coil. Low current will energize the coil and form a magnetic field. The magnetic field draws the core to the center of the coil and the contacts close.
SCHEMATIC OF A SOLENOID
1. Coil. 2. Switch terminal. 3. Battery terminal. 4. Contacts. 5. Spring. 6. Core. 7. Component terminal.