Diesel Engine Automatic Timer (Injection Timing Control)


As in the case of gasoline engine ignition timing, diesel engine injection timing must be advanced (or retarded) in accordance with the engine speed in order to obtain optimum performance. Advancing or retarding is controlled by the automatic timer in response to the engine speed.

Construction and operation

Fuel injection timing is controlled by changing the position of the roller, which touches the face cam. When the injection pump is not rotating, the roller is in the maximum retarding position. When the injection pump starts rotating and speed is increased, the timer piston moves to the left pushing the timer spring, as the fuel pressure inside the pump housing also increases. The slide pin connected to the piston converts the piston movement into the rotational movement of the roller ring. When the roller ring rotates in the opposite direction of the drive shaft, the injection timing advances. When the roller ring rotates in the same direction, the injection timing retards.

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