Question #133648

The Whitworth quick return motion mechanism has the driving crank AC=150 mm long.

The distance between fixed centres CD= 100 mm. The line of stroke of the ram passes

through the centre of rotation of the slotted lever whose free end is connected to the

ram by a connecting link. Find the ratio of time of cutting to time of return.

The distance between fixed centres CD= 100 mm. The line of stroke of the ram passes

through the centre of rotation of the slotted lever whose free end is connected to the

ram by a connecting link. Find the ratio of time of cutting to time of return.

Expert's answer

Quick return ratio = {Time of cutting/time of return}

= "\\frac{a}{b}"

= "360-\\frac{a}{a}"

AC_{2} =150 mm ,CD = 100mm

Cos "\\frac{b}{2}" = "\\frac{CD}{AC}"

= "\\frac{100}{150}"

"\\frac{b}{2}" = 48.2°

b = 96.4°

QRR = "\\frac{360-96.4}{96.4}"

=2.735

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