| 摘要 |
<p>The invention relates to a hydraulic motor assembly which includes a hydraulic servomotor operable in either direction with a control valve. When the motor is operated in a selected direction, as distinguished from the return direction, it is desired that external forces acting on linkage connected to the piston of the hydraulic motor do not alter the speed of the piston. The control valve has two operating positions and two sets of supply and return passages which facilitate operation of the servomotor in either direction. A brake valve between one of the servomotor ports and the control valve has a scanning port which scans or senses the downstream pressure of either of the control valve supply passages, depending on the control position of the control valve. When the servomotor is operated in the selected direction and an external force as referred to above is encountered, the brake valve operates in response to an increased pressure in the return line and a decreased pressure in the supply line, sensed through the scanning port thereof, to throttle the flow of return fluid in the return line to thereby dampen the tendency of the servomotor to accelerate responsive to the externally applied force. In addition to this function the brake valve is also arranged to allow the return line to be pressurized with supply fluid to effect movement of the servomotor in the return direction.</p> |
