Cams
A Shaped part on a pivot point that converts reciprocating motion to rotary motion. has two main parts:
- a A wheel attached to a crankshaft. - attached to a The rotating shaft a crank is joined to., which rotates
- a A bar that follows a cam around its circumference. - touches the cam and follows the shape, moving up and down
Cams can be produced in any shape, but the most common shapes are:
Circular
Circular cams use an off-centre pivot to cause the follower to move up and down. The follower will rise and fall by a reasonably large amount. These can be seen in pistons, for example on steam engines.
Pear
Pear cams are called this as they have the shape of a pear. It remains stationary for half a turn then gently rises and falls. These are used to make carousel horses rise and fall.
Snail or drop
Snail or drop cams have the appearance of a snail shell. It causes the follower to remain stationary for half a turn before gently rising and suddenly falling. They can only work by rotating in one direction. Used on production lines to make regular holes or cuts in an item as it rotates and drops at regular intervals.
Roller
Roller followers have a roller such as a ball bearing attached to the bottom of the following. These are accurate, low on friction and can withstand load, but are more costly to produce.
