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CAM TOY MECHANISMS - COMMON FAULTS

V. Ryan © 2006

 

CAM mechanisms work well if they are made accurately. However, any inaccuracy in making the device can lead to the mechanism ‘jamming’ when the profile rotates. Also, inaccurate making can lead to the movement of the follower being less than smooth when the profile rotates.

     

The diagrams show a typical CAM, mechanical toy. The follower has jammed as the profile rotates in a clockwise direction.
There are two possible reasons/faults that lead to this problem;

1. The slides are too far apart, allowing the follower to jam as the profile rotates.
2. The shape of the follower means that the movement of the mechanism is likely to jam or at best, move roughly rather than smoothly.

     

The two faults can be corrected quite easily by altering;

1. The shape of the follower. A ‘flat’ follower is used. This means that the movement of the profile and follower is more likely to be smooth and efficient.

2. The slides have been moved close together so that the follower is forced to move vertically, without ‘jamming’.

   

 

   

Another way of ensuring the smooth movement of the CAM mechanism is to ‘offset’ the position of the profile. The profile can be moved to the right or left. If moved to the left, the profile will rotate smoothly in an anticlockwise direction. Alternatively, if moved to the right the profile will rotate smoothly in a clockwise direction.

QUESTIONS:
1. Draw diagrams that represent alternative types of followers that, if used, could lead to the smooth movement of the follower, profile and image.
2. Are there any other potential problems with the way the mechanical toy is designed? If so, how would you correct them?

     
 
     
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