Control for hydrostatic piston pump - has unbalance between different piston ends counteracted by spring within sealed annulus supplied with control pressure

摘要

The control device consists of a piston (8) with a large and a small end, connected to the delivery pressure line. The resultant unbalanced force is counteracted by a spring (33) mounted in a sealed annulus (25) to which a controlled pressure is fed through valve (20). As the delivery pressure decreases, the control tends towards the natural position, allowing the pump speed to increase.