JPS5682654A - Brake valve - Google Patents

Abstract

PURPOSE: To enable optional control of the transient characteristic of sucking and discharging pressure at the time of start and stoppage of a hydraulic motor by providing a variable throttle valve in the bent pipe line of a relief valve.

CONSTITUTION: A balance piston type relief valve 27 is provided between the sucking and discharging ports of the hydraulic motor controlled by a hydraulic source 1 through the intermediary of a shifting valve 2 and a counter balance valve 3. In the bent pipe lines 71 and 72 of the relief valve 27 the variable throttle valve 50 is further provided. In the spool 52 of the variable throttle valve 50 are provided oil ducts 61 and 62, while in the end part thereof are provided orifices 59 and 60 communicating with pilot chambers 55 and 56. When, for instance, the pressure of the pipe line 25 rises at the start of the motor, a seat 29 is moved against a spring 31 and comes into the communication with the oil chamber 39, while the spool 52 moves to the right under the pressure of the pilot chamber 55 and releases the pressure to the pipe line 26 through the oil duct 62. Thus, the optional transient characteristic is obtained according to the shape of the oil duct 62.

COPYRIGHT: (C)1981,JPO&Japio