Fluid operated device

A fluid operated device comprising:

• a cylinder member, at least two mutually opposed piston members movable axially therein, a common working chamber within said cylinder member defined by opposing ends of said piston members and the inner wall of said cylinder member, said cylinder member being provided with inlet means and outlet means communicating with said working chamber for admission of working fluid to said chamber and for removal of spent working fluid from said chamber, respectively;
• a shaft member extending through said piston members and said cylinder member concentrically with said members, first coupling means coupling the piston members to one of the other mentioned members such that axial reciprocation of the piston members causes rotation of the piston members relative to said one of the other mentioned members;
• second coupling means coupling the piston members to the other one of the other mentioned members to prevent relative rotation of the piston members and said other one of the other mechanical members while permitting axial reciprocation of the piston members;
• and valve means in said working chamber operatively coaxially coupled to said shaft member for rotation with said shaft member relative to the cylinder member, said valve means comprising a substantially cylindrical ring member having an aperture therein which, on rotation of said valve means, selectively communicates with said inlet means and said outlet means in said cylindrical member to control movement of working fluid into and out of said working chamber through said inlet and outlet means.