Load-holding and load-lowering brake valve

摘要

A load-holding and load-lowering brake valve for linear and non-linear hydraulic motors. The valve (1) consists of a counterholding valve (13), which is connected in parallel with a first non-return valve (15) in the line to the lifting side of the motor, and a restrictor valve (12) which is connected in parallel with a second non-return valve (14) in the line to the lowering side (4) of the motor. The first non-return valve (15) directs hydraulic fluid to the motor past the counterholding valve and forces fluid from the motor to pass the counterholding valve when the latter is open. The second non-return valve (14) allows fluid from the lowering side of the motor to pass it and forces all the fluid to the lowering side of the motor to pass the restrictor valve. During increased load, i.e. during increasing pressure in the line (9) from the lifting side of the motor, the restriction of the restrictor valve increases so that the lowering speed of the motor drops. The counterholding valve is opened by the pressure in the line (10) between the restrictor valve (12) and the lowering side (4) of the motor reaching a certain value. <IMAGE>