This multi-block GIF sequence demonstrates the motion of a cam and lever system. The spring, anchored to a fixed point, holds the rolling cam follower, (red), against the cam as it rotates. In this example, the upward lever motion is supplied by the cam as it rotates through its' 'rise' segments, (there are actually two of them in this example). The downward motion is supplied by the spring as the cam rotates through its' 'fall' segment.

For edge profile or 'plate' cams such as the one shown, motion supplied by a cam rise is often refered to as being the 'positive' motion. Generally, positive motion is used to move away from any potentially interfering tool path such as nests on an indexed rotary dial or our in-line chassis. This precludes the chance of having a machine crash because of a broken spring.

The use of an air cylinder is often substituted for the spring to act as an 'air-spring'. Also, an air cylinder can be used as a 'lock-out' device. By actuating the air cylinder in the opposite direction, the cam lever is prevented from moving by holding the follower at the cam's major radius. This technique is often used, for example, at a rejection station where actuation is needed intermittantly.

Electric solenoids can also be used to lock-out motions. Although a spring is still required for the system, the solenoid is much faster than an air cylinder and therefore appropriate for high speed applications. Solenoids also require less maintenance.

If you would like to see more animations and information like this in the future, please write to me and let me know.
My email address is 'mike' (without the quotes but with the usual ampersand in front of our domain name). Thank you.


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Last modified July 20, 1996