Patent ID: 7926513

Claim:
A spool valve comprising: a valve housing having a shaft bore, an output port, and a drain port communicated with an exterior; a spool that is slidably supported within the shaft bore in a longitudinal direction, the spool having a first diameter portion and a second diameter portion; an output chamber defined between the valve housing and the spool, wherein the output chamber is communicated with the output port; a feed back chamber defined between the valve housing and the spool; a feed back port defined within the spool for providing communication between the output chamber and the feed back chamber; and radial damper means having: a radial damper chamber defined by a diameter difference between the first diameter portion and the second diameter portion; and a radial chamber restrictor providing restricted communication between the radial damper chamber and an adjacent chamber disposed adjacent to the radial damper chamber in the longitudinal direction, wherein the adjacent chamber serves as a spring chamber, in which a spring is provided for biasing the spool in the longitudinal direction; and the spring chamber is communicated with the drain port.