# What simple machine is a cam/eccentric?

Now I know that levers, wheels, screws, inclined planes, wedges, and pulleys (which I believe are actually levers in disguise), are the classical simple machines from way back when. Although I can classify things into these categories, I'm having trouble determining which of them a cam/eccentric fall into. They could be wheels, or they could be inclined planes...? If anybody hase some insight, clearing this up for me would really help!

Thanks,
PenguinCo.

Simon Bridge
Homework Helper
Why does it matter?
Some machines are comprised of combinations of simple machines - it is pointless to try to put everything into a simplistic taxonomy.

Note: a pulley may be used to obtain mechanical advantage - in which case it is a special case of a lever: a round lever. However, it can also be used as a pulley to change the direction of action of the tension in a cord. You can also use a rod and pivot to do this. When so used, the rod is a special case of a pulley.
In other words, a machine is properly classified by its function, not it's geometry. At least in terms of physics or engineering.

Baluncore
A cam/eccentric is just a circular wedge.

jack action
Gold Member
From Wikipedia:
Although they continue to be of great importance in mechanics and applied science, modern mechanics has moved beyond the view of the simple machines as the ultimate building blocks of which all machines are composed, which arose in the Renaissance as a neoclassical amplification of ancient Greek texts on technology. The great variety and sophistication of modern machine linkages, which arose during the Industrial Revolution, is inadequately described by these six simple categories. As a result, various post-Renaissance authors have compiled expanded lists of "simple machines", often using terms like basic machines,[8] compound machines,[5] or machine elements to distinguish them from the classical simple machines above. By the late 1800s, Franz Reuleaux[10] had identified hundreds of machine elements, calling them simple machines.

[...]

Classification of machines

[...]

However, a more successful strategy was identified by Franz Reuleaux, who collected and studied over 800 elementary machines. He realized that a lever, pulley, and wheel and axle are in essence the same device: a body rotating about a hinge. Similarly, an inclined plane, wedge, and screw are a block sliding on a flat surface.[28]

This realization shows that it is the joints, or the connections that provide movement, that are the primary elements of a machine. Starting with four types of joints, the revolute joint, sliding joint, cam joint and gear joint, and related connections such as cables and belts, it is possible to understand a machine as an assembly of solid parts that connect these joints.