IN PREVIOUS POST OF GOVERNOR “SENSITIVITY AND STABILITY” WE CAME TO KNOW WHAT IS SENSITIVITY OF GOVERNOR. HUNTING OF GOVERNOR IS CAUSED DUE TO OVER SENSITIVE GOVERNOR.
WHEN THE LOAD ON AN ENGINE CHANGES THE GOVERNOR TENDS TO OVER-CONTROL AND UNDER-CONTROL. THIS OVER-CONTROL AND UNDER-CONTROL CAUSES A FLUCTUATION IN ROTATIONAL SPEED WHICH IS REFERRED TO AS HUNTING. FOR EXAMPLE :- IF LOAD IS REMOVED FROM AN ENGINE THE SPEED INCREASES SOME AMOUNT ABOVE NORMAL. THE GOVERNOR THEN COMES INTO OPERATION AND REDUCES THE FUEL SUPPLIED BY THE FUEL PUMP. DUE TO FRICTION, TIME LAG ETC. THE GOVERNOR CAUSES THE FUEL REDUCTION TO BE IN EXCESS OF THAT REQUIRED AND THE FALL IN SPEED IS TOO MUCH. THIS CAUSES THE GOVERNOR TO INCREASE THE FUEL AGAIN AND THE ENGINE SPEED GOES SLIGHTLY ABOVE THE NORMAL. THIS SWING IN SPEEDS ABOVE AND BELOW THE MEAN OPERATING SPEED FOR THAT LOAD CONTINUES UNTIL EQUILIBRIUM IS REACHED AND HUNTING CEASES.