Thursday, September 25, 2008

Mechinacal toy

EXAMPLE USE OF A CAM

Below is a typical use of a cam. A simple toy based on a cartoon character (Ed the Handyman) is controlled by a cam and follower. As the cam rotates in an anticlockwise direction, the follower falls (diagram 2) and so does the arm of the toy. As the cam continues to rotate the arm begins to rise as seen in diagram 4. The cam shown is a pear shaped cam (named after its shape).



CAM PROFILES


Cams can be shaped in any number of ways and this is determined by the way the follower is to move. The shape of the cam is called the PROFILE. Examples of various cam profiles can be seen below.

Pear shaped cams are used on the shafts of cars. The follower remains motionless for about half of the cycle of the cam and during the second half it rises and falls.




Circular cams or eccentric cams produce a smooth motion. These cams are used in steam engines.




Heart shaped cams allow the follower to rise and fall with ‘uniform’ velocity.




What type of movement do you think this cam profile will give ? Drop cam


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