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Eccentric Cam

From DT Online

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Drescription

Cams with complex profiles can be complicated to manufacture, particularly with the type of equipment available in the school workshop. However, if all that is required is to produce a single up and down motion for every revolution on the cam, a circular cam rotating about a point offset from its centre (i.e. eccentric), will often suffice.


Features and Applications

An Eccentric Cam would normally provide the follower with Simple Harmonic Motion - (this can be defined as the projection of a point on the diameter of a circle as it precesses around it with constant angular velocity).


Note: They can be modelled, in wooden mechanical toys for example, by drilling a Ply or MDF disc off-centre and gluing it on to a rotating Dowel.


Note that the cam follower need not just move up and down in a reciprocating motion, but it can be a lever as shown, which will produce oscillating motion.


Animations
Eccentric Driven Pump - the red arrows indicate the rotation direction of the eccentric shaft and the

fluid moving direction. The front half of the case is removed.

DT Online Buyers' Guide
  • The use of Cams can most easily be explored using Contruction Kits such as those listed below.

Click top left to enlarge

Engino Engino Fischertechnik 536622 - Mechanic & Static 2 Engino Mechanisms Set Engino Gears Set
Engino "STEM Mechanics" Cams and Cranks Set Engino "STEM Mechanics" Levers and Linkages Set Fischertechnik 536622 - Mechanic & Static 2 Engino Mechanisms Set Engino Gears Set