It is also called Spring Loaded Governor. It is a special type of governor which has a spring attached between the balls of the governor. This spring is called Main Spring. The main spring is stretched and placed between the balls, this means that the main spring always exert a inward force to both the fly balls. It also has one more spring known as Auxiliary Spring. This auxiliary spring is connected to the sleeve through a pivoted lever.
Construction Of Wilson Hartnell Governor :-
In Willson Hartnell Governor, the fly balls are connected to each other
through a spring. This spring is called main string and is placed between the balls in a stretched position and exerts inward force to both the balls.Apart from this spring, this governor also has Auxiliary Spring.
This auxiliary spring is connected to sleeve via a lever. When the sleeve goes up , the other side of liver goes down and the auxiliary spring becomes stretched and pulls the other side of liver upward and the sleeve upward. This auxiliary spring helps to maintain the equilibrium speed of the governor.
These two balls are then connected to the rollers through Bell crank lever. This Bell Crank Lever is also known as Ring. The rollers are connected to the sleeve.The two fly balls and the spindle is connected to the engine shaft which rotates the spindle.
When the spindle rotates, the bell crank lever rotates with spindle and the fly balls connected to the crank lever also rotates , centrifugal force is experienced by the two balls which pulls the ball in outward direction away from each other but the main spring pulls the balls towards each other.
When the speed of rotation of spindle increases the radius of rotation of balls increases. Due to outward movement of balls the bell crank lever lifts up and hence the sleeve lifts up. So when the sleeve goes up the fuel supply decrease.
When the speed of rotation of spindle decreases the radius of rotation of balls decreases and the balls come closer to each other. Due to inward movement of the balls the bell crank lever goes down and hence the sleeve goes down.So when the sleeve goes down the fuel supply increases.