3208 – Governor

Cross Section Of Fuel System
(1) Lever. (2) Governor housing. (3) Load stop pin. (4) Cover. (5) Sleeve control shafts (two). (6) Inside fuel passage. (7) Fuel injection pump housing. (8) Drive gear for fuel transfer pump. (9) Lever (governor shaft). (10) Dashpot governor piston. (11) Dashpot governor spring. (12) Governor springs. (13) Spring seat. (14) Overfueling spring. (15) Thrust collar. (16) Load stop lever. (17) Carrier and governor weights. (18) Sleeve levers. (19) Camshaft. (20) Fuel transfer pump. (E.) Orifice for dashpot.

Fuel System Components
(5) Sleeve control shafts. (7) Fuel injection pump housing. (18) Sleeve levers. (21) Sleeves.

Lever (1) for the governor is connected by linkage and governor springs (12) to the sleeve control shafts (5). Any movement of lever (9) will cause a change in the position of sleeve control shafts (5).

When lever (1) is moved to give more fuel to the engine, lever (9) will put governor springs (12) in compression and move thrust collar (15) forward. As thrust collar (15) moves forward, the connecting linkage will cause sleeve control shafts (5) to turn. With this movement of the sleeve control shafts, sleeve levers (18) will lift sleeves (21) to make an increase in the amount of fuel sent to the engine cylinders.

When starting the engine, the force of overfueling spring (14) is enough to push thrust collar (15) to the full fuel position. This lets the engine have the maximum amount of fuel for injection when starting. At approximately 400 rpm, carrier and governor weights (17) create enough force to push overfueling spring (14) together. Thrust collar (15) and spring seat (13) come into contact. From this time on, the governor works to control the speed of the engine. Fuel systems equipped with fuel limiting Fuel Air Ratio Controls (FARC), will have the maximum amount of starting fuel limited by the FARC setting value.

Governor Parts
(10) Dashpot governor piston. (11) Dashpot governor spring. (13) Spring seat. (14) Overfueling spring. (15) Thrust collar.

When governor springs (12) are put in compression, the spring seat at the front of the governor springs will make contact with load stop lever (16). Rotation of the load stop lever moves load stop pin (3) up until the load stop pin comes in contact with the stop bar or stop screw. This stops the movement of thrust collar (15), the connecting levers, and sleeve control shafts (5). At this position, the maximum amount of fuel per stroke is being injected by each fuel injection pump.

The carrier for governor weights is fastened on the rear of camshaft (19) by bolts. When engine rpm goes up, fuel injection pump camshaft (19) turns faster.

Any change of camshaft rpm will change the rpm and position of governor weights. Any change of governor weight position will cause thrust collar (15) to move. As carrier and governor weights (17) turn faster, thrust collar (15) is pushed toward governor springs (12). When the force of governor springs (12) is balanced by the centrifugal force of the governor weights, sleeves (21) of the fuel injection pumps are held at a controlled position to send a specific amount of fuel to the engine cylinders.

The parts of the dashpot work together to make the rpm of the engine steady. The dashpot works as dashpot governor piston (10) moves in the cylinder which is filled with fuel. The movement of dashpot governor piston (10) in the cylinder either pulls fuel into the cylinder or pushes it out.

In either direction the flow of fuel is through orifice (E). The restriction to the flow of fuel by orifice (E) gives the dashpot its damping function.

When the load on the engine decreases, the engine starts to run faster and governor weights put force against governor springs (12). This added force puts more compression on governor springs (12) and starts to put dashpot governor spring (11) in compression. Dashpot governor spring (11) is in compression because the fuel in the cylinder behind dashpot governor piston (10) can only go out through orifice (E). The rate of flow through orifice (E) controls how fast dashpot governor piston (10) moves. As the fuel is pushed out of the cylinder by dashpot governor piston (10), the compression of dashpot governor spring (11) becomes gradually less.

When governor springs (12) and dashpot governor spring (11) are both in compression, their forces work together against the force of governor weights. This gives the effect of having a governor spring with a high spring rate. A governor spring with a high spring rate improves engine speed stability.

When the load on the engine increases, the engine starts to run slower. Governor weights puts less force against governor springs (12). Governor spring (12) starts to push spring seat (13) is connected to dashpot governor piston (10) by dashpot governor spring (11). When spring seat (13) starts to move, the action puts governor spring (11) in tension. As dashpot governor piston (10) starts to move, a vacuum is made inside the cylinder. The vacuum will pull fuel into the cylinder through orifice (E). The rate of fuel flow through orifice (E) again controls how fast dashpot governor piston (10) moves. During this condition, dashpot governor spring (11) is pulling against governor springs (12). This makes the movement of spring seat (13) and governor springs (12) more gradual. This again gives the effect of a governor spring with a high spring rate.

When the governor control lever is turned toward the Fuel-Off position with the engine running, there is a reduction of force on governor springs (12). The movement of the linkage in the governor will cause fuel control shafts (5) to move sleeves (21) down, and less fuel will be injected in the engine cylinders.

To stop the engine, turn the ignition switch to the “OFF” position. This will cause the shutoff solenoid to move linkage in the fuel injection pump housingto the shutoff position. Movement of the linkage will cause sleeve levers (18) to move sleeves (21) down; all fuel in the plunger and barrel chamber is returned to the gallery. With no fuel going to the engine cylinders, the engine will stop.

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