Section A
Q1.
(a) The crank of a crank and slotted lever quick return mechanism is driven at 120 rpm clockwise. The vertical distance between the centres of rotation of the crank and slotted lever is 50 cm. What should be the length of the crank if the quick return ratio is 1:2? Determine the angular velocity of the slotted lever, when the tool-post attains maximum velocity during cutting stroke.
(b) Square key of side d/4 and length l is used to transmit torque T from the shaft of diameter d to the hub of a pulley. Assuming the length of the key to be equal to the thickness of the pulley, find the average shear stress and crushing stress developed in the key.
(c) A tapering bar having d1 and d2 as diameters of end sections and another bar of uniform cross-section d are of same length l. Both are subjected to the same axial pull P. What should be the value of d in terms of d1 and d2 so that both the bars of same material will have same extension? Evaluate maximum stresses in both the bars.