Whitworth Quick Return Mechanism
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As can be seen in the animation opposite, the red linking pin has to travel a much greater distance around the top of the crank circle than the bottom during a full right to left stroke cycle. Since the crank is rotating with constant angular velocity the result is a left to right return motion being much quicker than the right to left forward stroke.
It is also a type of Coulisse Mechanism in reference to the slotted crank (i.e. as in Portcullis from the French ‘porte coulissante’, or 'sliding door', and derived from the Old French ‘Coulisse’ referring to a timber member grooved to take a sliding panel)
Features and Applications
At the bottom of the slotted arm, the peg only has to move through a few degrees to sweep the arm from left to right, but it takes the remainder of the revolution, and consequently more time, to bring the arm back. This mechanism is most commonly seen as the drive for a Shaping Machine.
|Coulisse Mechanism||Combined Coulisse Mechanisms - combination of two Coulisse Mechanisms. The green rocker has working stroke slower than return one..||Shaper with Coulisse Mechanism - reciprocating motion having working stroke slower than return one.|