• Author / Uploaded
• Ajibade Taofik

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Problem No.1 1993 Technical Drawing Ordinary Level, Paper 2(a) Engineering Applications, Question 3(a) A radial plate cam rotates at 20 revolutions per minute and operates an inline knife edge follower. The nearest approach of the follower to the cam centre is 35 mm. Draw the profile on the cam which will impart the following motion to the follower: Rise 48 mm with uniform velocity

: 0 to 1 second

Dwell

: 1 to 1.5 seconds

Return to initial position with uniform acceleration and retardation: 1.5 to 3 seconds

Motion type Rise 48 mm with uniform velocity Dwell Return to initial position with uniform acceleration and retardation

Duration of motion

Angular displacement

0 to 1 second 1 to 1.5 seconds

0° to 120° 120°to 180°

1.5 to 3 seconds

180°to 360°

Problem No.2 If a cam when rolling in an anti-clockwise direction imparts the following motion on the follower: 0° to 90° 90° to 130° 130° to 310° 310° to 360°

Rise with Simple Harmonic Motion for 60mm Remain at this Displacement (Dwell) Fall with Uniform Acceleration and Retardation through 60mm Remain at this Displacement (Dwell)

Construct the profile of the cam. The minimum cam radius is 40mm.

Solution 2

The diagram opposite shows an image of what the cam from the problem above may look like in 3D.