PINION-AND-SCREW MECHANISM OF TWIN VISES

When piston 1 is moved to the right by the action of fluid delivered to the left end of its cylinder, gear rack 2, rigidly attached to the piston rod, turns pinions 3 which are attached to screws 4. Each screw 4 has two portions, one with right- and the other with left-hand thread, and the screws are constrained against axial movement. When the screws are rotated, V-block jaws 5 with internal righ…