Pneumatically operated hydraulic pump

摘要

A pneumatically operated hydraulic pump includes a cylinder housing accommodating a main piston to subdivide the housing interior in two working chambers. The main piston is connected to a hydraulic piston for joint reciprocation so that the hydraulic piston can carry out a suction stroke when the main piston moves to one end position and a pressure stroke when the main piston moves to the other end position. Arranged laterally to the cylinder housing is a control mechanism for regulating a flow of working fluid alternately to the working chambers. The control mechanism includes a plastic valve casing for accommodating a control piston having opposite end faces of different size to define different effective areas and thereby realize reciprocation of the control piston by the working fluid. A slide shoe is guided in the valve casing for conjoint movement with the control piston. A displacement of the main piston into the two end positions actuates respective pilot valves which regulate the reciprocation of the control piston and the slide shoe to thereby move the main piston between the end positions which discharging working fluid via the deflection zone in the slide shoe to the atmosphere.