Abstract: A hydraulic brake slack adjuster disposed between a brake valve and an actuator of a brake mechanism has a first piston exposed to pressurized brake fluid from the valve and a second larger piston connected to the first piston for outputting brake fluid to the brake actuator with the fluid output to the actuator being greater than the volume of input fluid from the valve. This permits a smaller pump to be used while maintaining sufficient brake operation speed.

Abstract: A hydraulic power system having a plurality of variable displacement pumps for supplying pressurized fluid for manipulation of one or more implements includes control means operative to automatically adjust pump displacement to the output horsepower of a prime mover driving the pumps of a system. The control means includes an underspeed valve responsive to a deviation in the speed of the prime mover from any one of a wide range of selected speeds to transmit a fluid pressure signal to servo control means for adjusting the displacement of the pumps in proportion to engine output. The control means includes an infinitely variable orifice adjustable with throttle movement for adjusting the underspeed valve to respond to a deviation from a wide range of selected engine speeds.