Adjusting device for adjusting piston of hydrostatic engine

摘要

A control unit (8) has two control pressure chambers (11,12), each connected to a control line (9,10), and a control piston (16) between the chambers. The piston is moved from a neutral position dependant upon the pressure differential between the chambers, to connect one chamber to a feed pressure line (15). The piston is moved into neutral by a spring. A hydraulic centering device (21) has a switching valve (23) connected to the control lines, and a centering valve (22) connected to the chambers. Switching piston (37) and centering piston (28) are moved into end positions, when the control pressure in the lines has dropped, but a differential remains in the chambers. The chamber with the higher pressure is relieved via the valves, and the adjusting piston pressure is returned to neutral.