Fluid-actuated vises

Claim 1

In a fluid-actuated vise, the combination of a horizontally elongated hollow base having an upper surface provided with a longitudinally extending groove and with a longitudinal slot in the bottom of said groove, a fixed jaw projecting upwardly from one end of said base, an elongated inverted boxlike movable jaw slidable on said upper surface of the base toward and away from saId fixed jaw, an elongated fluid actuator completely housed in said movable jaw and slidably engaging said groove in the upper surface of the base, said fluid actuator including a screwthreaded lug projecting downwardly through said slot into said base, a screw shaft rotatable in the base and engaging said lug whereby said fluid actuator and said movable jaw may be prepositioned on the base relative to the fixed jaw, said fluid actuator comprising a pneumatic cylinder and a hydraulic cylinder disposed in tandem, a pneumatic piston and a hydraulic piston slidable in the respective cylinders, a plunger connected to the pneumatic piston and projectable into the hydraulic cylinder for sliding the hydraulic piston with a multiplication of force, a piston rod connected to the hydraulic piston and operatively engaging an end wall of said movable jaw, and means for admitting compressed air into said pneumatic cylinder, the length of said fluid actuator being lesser than the length of said movable jaw whereby the movable jaw may be slid on said base by the fluid actuator while the latter remains relatively stationary on the base, said piston rod projecting outwardly from said hydraulic cylinder and having a downwardly inclined end surface, said end wall of said movable jaw having an upwardly inclined inner surface engaged by the downwardly inclined end surface of said piston rod, whereby to urge the movable jaw downwardly against the upper surface of said base.