| 摘要 |
PURPOSE:To absorb an impact at the time of down starting or the like by using an output contact of a pressure switch at the discharge side of a hydraulic pump for a down operation command contact of an induction motor and an operating command contact of a solenoid selector valve lying between the hydraulic pump and a hydraulic jack. CONSTITUTION:When a down operating command is generated, a variable throttle 24a of an auxiliary solenoid selector valve 24 installed in a bypass pipeline 23 is opened, and pressure oil at the side of a hydraulic jack 1 passes through this variable throttle 24a and gradually flows into a pipeline between a hydraulic pump 10 and a solenoid selector valve 13, whereby hydraulic pressure in a hydraulic circuit goes up. When this hydraulic pressure goes up to the setting value of a pressure switch 25, the output contact 25a is closed and an induction motor 11 and the solenoid selector valve 13 are excited, and the hydraulic circuit is opened, the pressure oil in the hydraulic jack 1 is exhausted dead load of a cage 5, rotating the hydraulic pump 10, and thereby a speed controller 17 controls a down speed of the cage 5 by dint of dynamic braking of the induction motor 11. Thus, an impact at the time of down starting is absorbed and, what is more, time until ordinary down travel starting can be shortened. |
