US Patent 7997190 Dual force ram drive for a screw press

Precise motion of the ram of a fastener press is controlled by high torque and low torque motors for high speed/low force and high force pressing of the ram by the ram, respectively. The high torque motor means drive passes through a bidirectional overrunning clutch. The clutch is controlled by the relative motion of the two separate motor drive speeds of which are regulated by a controller. The clutching motion is therefore controlled only by the relative speed of its drive versus driven components. This provides an extremely smooth and responsive transition between high speed/low force and low speed/high force operation of the ram so that the pressing cycle can be as fast and efficient as possible.