RECIPROCATING ROTARY-LINEAR TRANSFORMATION

Some mechanisms work in the opposite way, transforming rotary motion into reciprocating linear motion.

Crank and rod mechanism

 

The piston moves a rod forwards and backwards. This rod turns the first Wheel. The second Wheel  turns because it is connected to the first Wheel by another rod.

Crankshaft mechannism

We can connect multiple rods to one shaft. The rods are connected to cranks, and the cranks are connected to the crankshaft.

 https://www.youtube.com/watch?v=ZJuZ92zvgfk, this is an animation of crankshaft mechanism.

A crankshaft mechanism can synchronise the movements of various parts.

Cam mechanisms

A cam is an irregulary shaped device that rotates on a shaft. When the cam rotates, it pushes a special bar called a follower. The follower can move other parts ori t cab turn a switch on and off. In some mechanisms, a spring pushes the follower back to its original position.

 

We can put multiple cams on one shaft, called a camshaft. We can use a camshaft to synchronise the movements of various parts, such as the valves of an internal combustion motor. A clockwork music box also has a camshaft mechanism.

There is a metal roller with many tiiny bumps. When the roller turns, the bumps at like cams, moving a series of metal teeth that play musical notes.