PTD Injectors.

Principles of Gasoline And Disesel Fuel Systems
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(b) The governor controls the flow of the fuel from the gear pump,

as well as the maximum and idle speeds. The mechanical governor is actuated

by a system of springs and weights and has two functions: First, the

governor maintains sufficient fuel for idling with the throttle control in

idle position; second, it will restrict fuel to the injectors above maximum

rated rpm. The idle springs (in the governor spring pack) position the

governor plunger so the idle fuel port is opened enough to permit passage of

fuel to maintain engine idle speed.

During operation between idle and maximum speeds, fuel flows through the

governor to the injector in accordance with the engine requirements, as

controlled by the throttle and limited by the size of the idle spring

plunger counterbore on the PTG fuel pumps. When the engine reaches governed

speed, the governor weights move the governor plunger, and fuel flow to the

injectors is restricted. At the same time, another passage opens and dumps

the fuel back into the main pump body. In this manner, engine speed is

controlled and limited by the governor, regardless of throttle position.

Fuel leaving the pump flows through the shutdown valve, inlet supply lines,

and into the injectors.

control engine speed above idle, as required by varying operating conditions

of speed and load. In the PTG pump, fuel flows through the governor to the

throttle shaft. At idle speed, fuel flows through the idle port in the

governor barrel, past the throttle shaft. To operate above idle speed, fuel

flows through the main governor barrel port to the throttling hole in the

shaft.

(d) The fuel shutdown valve is located on top of the fuel pump.

It shuts off fuel to the injectors. With the master switch on, the solenoid

opens the valve. With the switch off, the spring loaded valve returns to

the OFF position. In case of an electrical failure, rotation of the manual

knob clockwise will permit fuel to flow through the valve. The knob is

located on the front valve.

(3) PTD Injectors. A PTD injector is provided at each engine

cylinder to spray the fuel into the combustion chambers. PTD injectors are

of the unit