Change-over valves

Claim 1

In a fluid path selector assembly, the combination of: a. a fluid flow selector valve comprising: a valve body defining a valve chamber with a main port for communication to the supply of a fluid circuit and a pair of oppositely disposed subsidiary ports; valve means mounted in said chamber for movement thereacross to close off selectively one or the other of said subsidiary ports and communicate the unclosed subsidiary port with said main port; a pair of subsidiary chambers defined in said valve body into each of which one of said subsidiary ports opens; and a piston means fast for linear movement with said valve means and mounted in a cylinder defined within said valve body; b. a pair of fluid handling devices each having an inlet and an outlet, said devices being in communication via their respective inlets one with one of said subsidiary chambers and the other with the other subsidiary chamber by which said fluid handling devices mAy selectively be supplies with fluid from said main port in dependence upon which of said subsidiary ports is communicated by said valve means with said main port; and c. a four-way flow control valve having a body defining a first port in communication with said main port; a second port in communication with said cylinder to one side of said piston means, a third port in communication with said cylinder to the other side of said piston means; and a fourth port communicating to discharge; and a change-over valve selectively movable within said control valve body for communicating said first port selectively with either of said second and third ports and, concomitantly, said fourth port selectively with the unconnected third or second port, by which fluid from said main port is selectively directable to one side or the other side of said piston means to urge said piston means along said cylinder, thereby to effect discharge of inoperable fluid therefrom to waste and valve operating motion of said valve means within said valve chamber.