US Patent 8002155 Slide valve device for automatic surface pressure application

A slide valve device for automatic surface pressure application including a slide valve having a three-layer structure, in which the movable bodies of the seal case is slidable on a support surface of a spring holder. The slide case and the seal case are coupled with each other by means of a coupling device or a coupling stopper, and the cases are slid together by means of an actuator so as to apply and release a surface pressure.