What is mechanical governor? Explain its working.

A Governor is a mechanical device used to govern the speed of machines like engines. From small engines to tractors to standby power systems even your automobiles are enabled with governors to regulate their speed. It allows the engine to run at the speed you select, without any effect of changing the load.

With the continuous change of load, the configuration of governor varies that helps to control the supply of fuel required by the engine. In simple words, Mechanical Governor is a speed control device, with suspended masses that respond to the changing speed with the help of inertia.

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There are basically two types of governors namely Centrifugal Governor an Inertia Governor. Inertia Governors are more sensitive than Centrifugal Governor but on the other hand, it’s very difficult in Inertia Governor to balance the revolving parts. Due to this reason Centrifugal Governors are used more than Inertia Governors.

Mechanical Governor (Centrifugal Governor)-

This Speed- sensing device uses gears and flyweights to detect the changing load and adjusts the throttle accordingly. The mechanical governor works on balancing the centrifugal force of the flyweights and in return balances the equal and opposite radial force acting on these rotating balls which are termed as controlling force.

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Suppose you are operating an engine at a light load applied to it. In this situation, the carburettor delivers small amount if air-fuel mixture to the combustion chamber. Now as the crankshaft spins, the centrifugal force created opens the flyweight. As they operate the pressure is applied on the governor cup and crank which are directly linked to the throttle valve. This action of the flyweights pulls the throttle to the closed position.

Now in other situation as the load on the crankshaft are increased leads to the slow spinning of the flyweights. This decreases the centrifugal force on the flyweights and leads to less pull of the throttle valve to the closed position and the supply of the working fluid increases.

How Mechanical Governor works-

The Mechanical Governor basically consists of two balls of equal mass, attached to the arms. The rotating ball is also termed as governor balls and fly balls.  These balls are well attached to the arms and tend to revolve with the spindle.

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The upper end of these arms is well attached to the spindle, which allows the ball in their up and down movement while revolving on the vertical axis. From below the arms are linked to the sleeve which is also keyed to the spindle and is allowed to revolve with the spindle. The sleeve is also allowed to slide up and down while revolving.

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With the increase of speed, the balls and the sleeve rises up and tends to fall down with the decrease in speed. The up and down movement of the sleeve is controlled by stopper on the spindle.  The sleeve is connected to the throttle valve with a bell crank lever. The supply of the air-fuel mixture increases when it falls and decreases with the rise of the sleeve.