Question

A cam should be designed only using uniform rise and fall within the second half of cam profile, the first half is dwell period, without any dwell period in between the rise and fall periods and rise and fall periods should be same. The maximum rise in follower is 55 mm. How much the follower will rise when the follower is 240 degrees from its initial position of a cam?

(a) 18.3

(b) 0

(c) 27.5

(d) 36.6

I had been asked this question at a job interview.

This interesting question is from Cam topic in section Curves used in Engineering Practice of Engineering Drawing

Answer 1

Correct choice is (a) 18.3

The explanation: According to the given conditions there is only movement in follower from 180 degrees to 360 degrees of shaft rotation and between it, at the middle of rise-fall period the follower make maximum rise that is at 270 degrees. And this follows the linear function. 360- 180 = 180, 360- 270 = 90, 360-240= 120 degrees. For 90 degrees from 180 degree position it is 55 mm so for other 30 degrees it will be 55 x 1/3 = 18.3 mm when the follower is 240 degrees from its initial position of the cam.