A presentation on the whitworth quick return mechanism, that covers the historical development of the mechanism, its applications, mathematical analysis, Solidworks and AdamsView Simulation images
2. INTRODUCTIONThe Whitworth quick return mechanism converts rotary motion into reciprocating motion, but
unlike the crank and slider, the forward reciprocating motion is slower rate than the return
stroke. This is why it is called quick return mechanism.
This mechanism is made of a driving crank and of a driven slider crank. In the considered
configuration, the fixed pivot of the driven crank is located on the outside of the circle on which
the end of the driving crank moves. This leads to an alternated motion of the slider crank.
The angular speed of the driven crank is variable. The duration of the motion for its part
corresponding to the blue arc is shorter than the one related to the red arc. This is why this
device is named quick return mechanism, which was used in crank shapers, with the slow part or
the stroke being used for the working time of the tool and the quick part for the non-productive
time.
Whitworth quick return mechanism was developed by the British manufacturer Sir Joseph Whitworth around 1840.He was a machine tool builder and he sensed that speed of cutting tool on the shaping machines in his factory were not quick enough. So he adopted an inversion of the slider crank mechanism and fixed the crank. In the resultant mechanism backward stroke was faster than the forward stroke hence this mechanism speeded up the return of the cutting tool to the beginning of the cutting stroke thus saving time.