Control Rod Stops

Fig. 11 Fixed Control Rod Stop:

The travel of the control rod is usually limited (full load delivery) by an adjustable stop. There are various types of control rod stops. A distinction is made between control rod stops installed on the injection pump and the governor.
With regard to pump installed control rod stops a distinction is made between fixed control rod stops and spring loaded stops. The fixed control rod stop Fig. 11, is adjustable by means of a screw and is locked with a lock nut. It can be adjusted to full load delivery or to starting fuel delivery. In engines requiring a larger quantity of fuel for starting than for full load operation the control rod or the linkage of the governor is provided with a further stop which can be made temporarily inoperative for starting, but which, during operation, limits the full load delivery.

Fig. 12 Spring Loaded Control Rod Stop:

The spring loaded control rod stop Fig. 12, is usually installed in minimum-maximum speed governors. It can be adjusted with the adjusting bushing which is secured against turning by means of the lock nut. At pump speeds of above 400 - 500 RPM, the control rod stop limits the fuel delivery. If the driver depresses the accelerator pedal fully with the engine stopped, the spring in the stop bushing will yield. The control rod travel becomes greater than at full load, which results in a greater fuel delivery. However, as soon as the engine is running, the governor takes effect and draws the control rod back into the idle position just before intermediate idle speed has been reached (speed regulation).