| 摘要 |
<p>The device has hydraulic lines (12,14) connected to hydraulic fluid inlet and hydraulic fluid return line for lifting/lowering hydraulic load. A drain control valve (26) is opened/closed to control flow of hydraulic fluid from load. A pilot valve (30) controls pilot pressure in control input (28) of drain control valve for opening pilot valve. A pressure-measuring device measures pressure in line (14) during lowering of load. A control device (42) controls pilot valve based on measured pressure such that preset pressure prevails in line (14) for opening drain control valve.</p> |
