Basic speed control mechanism with speed governor in a diesel engine system.

Speed Governor is an electromechanical device in diesel engine. Its function is to maintain & control the speed of the engine by controlling the amount of fuel to engine. The core concept in power generation is that, the speed of engine or turbine must be constant or +-x of it. A fluctuation in speed would cause fluctuation in voltage and frequency.

Governor maintain the speed of running engine by controlling the amount of fuel supply to engine. If the speed is low or high other than nominal value, then it increase or decrease the amount of fuel to engine. The signal governor receives from a certain control system.

Governor working principle:

During normal operation the engine speed is controlled by a governor (1) which regulates the injected fuel quantity to correspond with the load and engine speed.

The regulation movement is transferred to the control shaft (10) through a adjustable link rod (2).The movement from the control shaft, to the injection pump fuel racks (15), is transferred through the regulating lever (6) and the spring (7).

When one of fuel rack is jammed:

The torsion spring (5) enables the control shaft and, consequently, the other fuel racks to be moved to a stop position, even if one of the fuel racks has jammed. In the same way the torsion spring (7) enables the regulating shaft to be moved towards fuel-on position, even if an injection pump has jammed in a no-fuel position. This feature can be of importance in an emergency situation.

Engine stop control with governor.

The engine can be stopped by means of the stop lever (16). When the stop lever is moved to stop position, the lever (17) actuates the lever (9) forcing the regulating shaft to stop position.

1.Governor 2.Adjustable link rod 3.Lever for governor 4.Screw 5.Spring ,6.Lever for injection pump 7.Spring 8.Bearing housing 9.Lever 10.Control shaft 11.Load limiter 12.Lever for control shaft 13.Adjustable link rod 14.Adjusting screw 15.Fuel rack 16.Stop lever 17.Lever for stop lever 18.Dog

Electro-pneumatic tripping device for Engine:

The engine is provided with an Electro-pneumatic device with tripping speed about 15 % above the nominal speed. The electro-pneumatic device moves every fuel rack to a no-fuel position by means of a
pneumatic cylinder on every injection pump. The cylinder actuates direct on the fuel rack. The electro-pneumatic device can also be tripped manually

diesel engine
Typical diesel engine


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