A device that stops engine if it’s speed exceeded the maximum. It is necessary for the engine to trip if the speed exceeds beyond the set speed as the inertia and the centrifugal forces created because of high speed of the engine will give large amount of stresses onto the moving parts which may cause the failure of the moving parts and bottom end bearing bolts. Hence to avoid these damages, it is necessary that as soon as the speed increases beyond the preset limit the fuel should be cut-off and the engine should be made to stop. This is achieved either mechanically or electrically depending upon the engine and the type of injection system fitted. Mostly it is at 10% above the normal running rpm. If the engine trips because of overspeed, the restarting of the engine is possible only after resetting the fuel lever to the start position and then starting the engine. This is provided so that continuous stopping and starting of engine is prevented in case if the engine trips and overspeeds.