PURPOSE: To correct the floor position of a cage easily by driving a sub-pump every time the cage stops and feeding delivery oil into a hydraulic jack or lowering the pressure in the hydraulic jack by a switching valve according to the stop position of the cage.
CONSTITUTION: A hydraulic jack 6 is connected from a suction filter 3 in an oil tank 1 through a sub-pump 1, a duct 9, a check valve 4 and a duct 10. Every time a cage stops, the sub-pump 1 is operated to detect (12) the displacement of a cage 5 by a rope 18 and a pulley 19 and input it into a control device 16. When the cage 5 stops lower than the specified position, a switching valve 7 between the duct 9 and the oil tank 11 is operated by the output signal 15 of the control device 16 so as to feed oil pressure into the jack 6 through the check valve 4, thus moving the cage up. When the cage 5 is displaced higher, a switching valve 8 between the duct 10 and the oil tank 11 is controlled (14) to return oil into the tank 11. The stop position of the cage 5 is thereby corrected to the normal level without time delay.
HAGITANI TOMOFUMI
TAKEDA KAZUTOSHI
ARAHORI NOBORU
MASUDA KATSUTARO
NAKAMURA ICHIRO
