Hydraulic power booster apparatus

摘要

A hydraulic actuated pressure booster unit includes a differential power piston and an integral control valve controlling the pumping direction and action. The control valve has a reciprocally mounted tubular spool member in a cylinder valve body. The spool member has a control passageway and a plurality of spaced spools, one of which mates with the power piston passage to form a first valve for transfer of oil to the pumping chamber and from a transfer chamber to an exhaust passageway. A pair of spaced spools slide in stepped control chamber forming a control bore and exhaust bore connected by the spool passageway to the pumping chamber via the first valve. A sequence valve connects the exhaust bore to the exhaust through a directional control valve. The sequence valve is controlled by the output working pressure. A pilot valve controls the load connection to the one end of the cylinder and a high pressure relief valve limits the total pressure created within the working system. The valves and operating sections are axially mounted in longitudinal spacing within a tubular housing having fluid passages formed by recesses in the sidewalls and sealed by an outer shell.