Hydraulic control system for hydrostatic power transmission - uses two-level pressure limiting valve, and leakage oil circuit

摘要

The control system contains a hydraulic pump (1) of variable swept volume driven by a motor (2) with a hydraulic drive (3) linked by a high pressure circuit (4). A leakage oil pressure circuit (5) and control circuit (6) are also present. A pressure limiting valve (7) is present in the high pressure circuit. The valve contains a pre-control valve (9) and main control valve (8). Spring (16) holds off piston valve (15) until the pressure reaches a set level. A spring (18) holds off the valve (17) at a lower pressure so that the leakage circuit is activated first. A pilot valve (23) allows a gradual variation of the control to leakage system circuit cross section. The control circuit then operates by varying the swept volume of pump (1). USE/ADVANTAGE - Auxiliary machine drive, e.g. ventilator, compressor, generator, esp. hydrostatic servo drive in railed vehicle. Requires no hydraulic auxiliary energy to bring adjusting pump to zero delivery. Securely brings the rest if need be.