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What is Centrifugal Governor |Construction and Working

What is Governor :

A Governor, or speed limiter, is a device used to measure and regulate the speed of a machine, such as an engine. A classic example is the centrifugal governor, also known as the watt. [1-3] Centrifugal governors were used to regulate the distance and pressure between millstones in windmills since the 17th century. Early steam engines employed a purely reciprocating motion, and were used for pumping water an application that could tolerate variations in the working speed. It was not until the Scottish engineer James Watt introduced the rotative
steam engine, for driving factory machinery, that a constant operating speed became necessary. Between the years 1775 and 1800, Watt, in partnership with industrialist Matthew Bolton, produced some 500 rotative beam engines. At the heart of these engines was Watts self-designed “conical pendulum” governor: a set of revolving steel balls attached to a vertical spindle by link arms, where the controlling force consists of the weight of the balls.

Centrifugal governor

A flyweight mechanism driven by the engine is linked to the throttle and works against a spring in a fashion similar to that of the pneumatic governor, resulting in essentially identical operation. A centrifugal governor is more complex to design and produce than a pneumatic governor. However, the centrifugal design is more sensitive to speed changes and hence is better suited to engines that experience large fluctuations in loading.

Centrifugal Governor is shown above in the figure which maintains the mean speed of the engine when there is variations in the load. It basically works on the principle of balancing of the centrifugal force on the flyballs by equal and opposite radial forces.

Constructional Details:

Spindle axis is driven by bevelled gears of engine shaft which rotates the flyball and it is connected to the sleeves with the help of links. Sleeves can slides up and down along with flyball along the spindle axis. To limit the motion of sleeves up and down two stops are there. Throttle valve is connected to the sleeves through bell crank lever which can controls opening and closing of the valve.

Working:

When the load on engine increases, its speed decreases. The flyball’s speed and speed of governor’s spindle which is geared with engine shaft also decreases and consequently throttle valve opens, increases the supply of fluid and hence engine speed increases and vice-versa when load decreases on engine, its speed increases and hence throttle valve closes to decrease the supply of fluid and hence speed decreases.