Spool-sleeve type change-over valve

Claim 1

A spool-sleeve type change-over valve comprising: a cylindrical casing provided with a fluid intake port, a pair of output ports located one on each side of said intake port, and a pair of discharge ports located respectively on the outer sides of said output ports; a sleeve fixedly fitted in said casing and internally defining a cylindrical valve chamber, said sleeve being provided with rows of circumferentially aligned apertures including intake apertures, output apertures and discharge apertures respectively in open communication with said intake, output and discharge ports in said casing; a spool slidably received in said sleeve and having a center land slidable across said intake apertures to connect said intake port with either one of said output ports and a pair of discharge control lands slidable across said discharge apertures to communicate the disconnected output port with the corresponding discharge port; and operators provided at the opposite ends of said casing to shift said spool between two change-over positions thereof; each of said intake apertures having an axial width less than the axial width of said discharge apertures, the axial width of said intake apertures being within the range of widths which will permit cylinders connected to said output ports to attain the same response velocity that is attained when the intake and discharge apertures all have equal axial widths.