Technical Drawing - Exam Papers - Ordinary - 2006 - Engineering

Question 3

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A radial plate cam has a minimum radius of 40mm and a camshaft diameter of 22mm.
The cam rotates in a clockwise direction and imparts the following motion to an inline knife-edge follower:
0° to 180° Rise 60mm with uniform acceleration and retardation;
180° to 210° Dwell;
210° to 300° Fall 40mm with simple harmonic motion;
300° to 360° Fall 20mm with uniform velocity.
Draw the profile of the cam.
Include the displacement diagram as part of the solution.

Shown is a link mechanism. A and C are fixed points. Crank AB rotates in an anti-clockwise direction. Link BDEF is pin jointed at B and D. Link CD oscillates about point C.
(i) Using a line diagram to represent the mechanism, plot the locus of point F for one revolution of the crank AB.
(ii) Draw the profile of a simple machine guard about the mechanism with a minimum clearance of 15mm.

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