GOVERNOR & IT'S CLASSIFICATION

GOVERNOR

A device which is used to maintain the rotary speed of engines and other prime movers, is called governor.

Fig. Governor

The function of a governor is to maintain the speed of an engine within specified limits whenever there is a variation of load. In general, the speed of an engine varies in two ways - during each revolution and over a number of revolution. In the former case, it is due to variation in the output torque of the engine during a cycle and can be regulated by mounting a suitable flywheel on the shaft. In the latter case, it is due to variation of load on the engine and requires a governor to maintain the speed. The operation of a flywheel is continuous whereas that of governor is more or less intermittent. A flywheel may not be used if there is no undesirable cycle fluctuation of the energy output, but a governor is essential for all type of engines as it adjusts the supply according to the demand.

If the load on the shaft increases, the speed of the engine decreases unless the supply of fuel is increased by opening the throttle valve. On the other hand, if the load on the shaft decreases, the speed of engine increases unless the fuel supply is decreased by closing the valve sufficiently to slow the engine to it's original speed. The throttle valve is operated by the governor through a mechanism for the purpose.

Types of Governors
Governors can broadly be classified into two types-

1- Centrifugal governor

This is the more common type. Its action depends on the change of speed. It has a pair of masses, known as governor balls, which rotate with a spindle. The spindle is driven by an engine through bevel gears. The action of the governor depends upon the centrifugal effects produced by the masses of the two balls. With the increase in the speed, the balls tend to rotate at a greater radius from the axis. This causes the sleeve to slide up on the spindle and this movement of the sleeve is communicated to the throttle through a bell crank lever. This closes the throttle valve to the required extent. When the speed decreases, the balls rotates at a smaller radius and the valve is opened according to the requirement.

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Types of centrifugal governors are-

• Pendulum TypeWatt governor
• Gravity GovernorPorter Governor
• Proell Governor
• Spring LoadedHartnell Governor
• Wilson Governor
• Hartung Governor
• Pickering Governor.

2- Inertia governor

In this type the positions of the balls are affected by the forces setup by an angular acceleration or deceleration of the given spindle in addition to centrifugal forces on the balls. Using suitable linkages and springs, the change in the position of the balls is made to open or close the throttle valve.

Thus, whereas the balls are operated by the actual change of engine speed in the case of centrifugal governors, it is by the rate of change of speed in case of inertia governors. Therefore, the response of inertia governors is faster than that of centrifugal types.

Now the centrifugal governors are classified in the following given type-

Fig. Governor Classification

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