PURPOSE: To allow a piston to take a target position at a high speed so as to prevent hunching, by connecting cylinder oil chambers to each other via an orifice, with one cylinder oil chamber connected to a pressure supply source and the other to a valve device.
CONSTITUTION: The sleeve 34 of a valve device 30 is coupled with a piston 12, and a port P1 is connected via an oil passage L1 to an oil pressure supply source 5, while an oil passage L5, which is provided with an orifice 9, is branched from said L1 so as to be connected to a port F, and further connected, to a port E, via an oil passage L6 further branched therefrom, while a port P2 is connected via an oil passage L7 to the oil pressure supply source 5, and a port T is connected via the oil passage L2 to a tank 6. The aforesaid constitution allows the motion in one direction to be constantly of two speeds, without generating any overshooting even under a heavy load of inertia, while the motion in the other direction, being free from hunching during a return motion, permits a quick positioning to a target position, even in case of overshooting.
HAYASHI KIYOSHI
KIHARA KAZUYUKI
ANDO TAKESHI
NAKAO HIROTOSHI
