US Patent 7926513 Spool valve

A spool valve includes a valve housing, a spool and radial damper device. The valve housing has a shaft bore. The spool is slidably supported within the shaft bore in a longitudinal direction, and the spool has a first diameter portion and a second diameter portion. The radial damper device has a radial damper chamber and a radial chamber restrictor. The radial damper chamber is defined by a diameter difference between the first diameter portion and the second diameter portion. The radial chamber restrictor provides communication between the radial damper chamber and an adjacent chamber disposed adjacent to the radial damper chamber in the longitudinal direction.