Hydrostatic motor with fluid circulation in housing

摘要

The hydraulic motor has a cylinder drum rotating inside a housing and fitted with pistons. The motor has high- and low-pressure connections (4,5) and separate lubricating control valves (18,19). The lubricating valves open at pressures lower than the normal pressures of the high-pressure and low-pressure feeds to ensure sufficient cooling and lubrication of the motor when on standby and at low torque. Each lubricating valve has a spring-loaded valve element which is pushed against the spring return by the external hydraulic pressure to close the valve. When the external hydraulic pressure drops below a set level the valve opens. The two lubricating valves operate at different switching pressures, corresponding to the two levels of pressure feed. No pressure balance valve is required between the hydraulic feeds. At higher motor torque there is sufficient fluid leakage to ensure cooling and lubrication.