Abstract: An electroresponsive device is energized to actuate an internal combustion engine throttle for switching the engine from idle to a higher speed. The engine drives a hydraulic pump that supplies fluid through a control valve, then a cylinder lock, for driving hydraulic work cylinders. A first switch responds to a low pressure level being exceeded, due to fluid being directed by the control valve to an actuator, to increase engine speed, thereby making the pump pressure higher. A second switch responds to the higher pressure to continue the increased engine speed. When the control valve is restored to neutral position, the hydraulic fluid bypasses through the control valve directly to a sump and the second switch responds to the lower pressure by allowing the engine to go idle speed. A time delay device is provided for disabling the first switch during the time that pressure is dropping from the higher level to below the lower level.