Variable stroke cylinder

Claim 1

In a variable stroke cylinder, a cylinder member, a pair of piston members spaced a predetermined distance from each other so as to define a space therebetween, said piston members being mounted for simultaneous axial movement in said cylinder member during normal operation thereof, means for selectively moving at least one of said piston members relative to the other said piston member for adjustably varying the stroke of said piston members by moving said piston members relative to each other to vary said predetermined distance between said members, the improvement which enables rapid and extensive stroke adjustment therein and which comprises in combination therewith: vent means communicating with said space between said piston members for venting said space when said predetermined distance between the piston members is varied to vary the stroke of the cylinder to maintain the pressure in said space substantially constant during said stroke adjustment, wherein said vent means comprises a bleed orifice in one of said piston members communicating between the face of said piston member adjacent said space and the opposite face of said piston member.