Whitworth Quick Return Shaper Drive Mechanism

Whitworth Quick Return Shaper Drive Mechanism

Whitworth Quick Return Shaper Drive Mechanism - Crank BC revolves at a uniform speed. During cutting stroke the point C travels from Y to X through Z. The ram is returned at high speed as the crank rotates from X to Y through T. Then:

Time for cutting stroke / Time for return stroke =360 - θ/θ

Whitworth quick return mechanism

Since θ is smaller than 360 - θ, the time for cutting is more than the idle (stroke) time and thus the name quick return motion. The stroke length (in this mechanism) can be changed by varying the radius AE.

Since the change in stroke length alters the cutting speed, it necessitates a change of gear to get desired cutting   speed.