To provide a spool change-over valve excellent in operability of an actuator and high in reliability.
This spool change-over valve constituted of a housing 1 furnished with a plurality of oil chambers including a pump line 4, a cylinder port 6 and a tank line 3 and a spool 2 supported liquid-tightly and free to slide in this housing 1 and to change supply of oil to a plurality of the oil chambers is provided with an auxiliary oil chamber 33 between the cylinder port 6 and the tank line 3, provided with cutout parts 5-1, 5-2 on an outline part of a large diametrical part 2D of this spool and provided with cutout parts 5-3, 5-4 on an outline part of a large diametrical part 2H and it is devised to discharge pressure oil to the tank line 3 while gradually lowering pressure through the cutout parts 5-3, 5-4, the auxiliary oil chamber 33 and the cutout parts 5-1, 5-2 at the time when the pressure oil of the cylinder port 6 is discharged to the tank line 3.
ARAYA TAKASHI
KOBAYASHI MASAYUKI
