+1 vote
in Machine Kinematics by (38.0k points)
A crank and slotted lever mechanism used in a shaper has a centre distance of 300 mm between the centre of oscillation of the slotted lever and the centre of rotation of the crank. The radius of the crank is 120 mm. Find the ratio of the time of cutting to the time of return stroke.

(a) 1.62

(b) 1.72

(c) 1.82

(d) 1.92

I got this question during an online exam.

Question is from Single Slider Crank Chain and its Inversions in portion Simple Mechanisms of Machine Kinematics

1 Answer

0 votes
by (106k points)
The correct answer is (b) 1.72

Best explanation: Given : AC = 300 mm ; CB = 120 mm

sin∠CAB = sin (90°−α/ 2)

CB/AC = 120/300 = 0.4

∠CAB = 90°−α/ 2

or α / 2 = 90° – 23.6° = 66.4°

α = 2 × 66.4 = 132.8°

We know that

Time of cutting stroke/ Time of return stroke = 1.72.

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