TRANSFORMATION OF MOTION

The linear motion can be undirectional or reciprocating.

- Rotary-linear transformation.
· Wheel.
If the wheels isn't enough friction, the wheels can slide out of control.
A wheel moves forward a distance that is equal to its circumference.

· Rack and pinion mechanism.
A rack and pinion mechanism has two parts.The rack is a bar with many teeth and the pinion is a gear with teeth that interlock with the rack. When the pinion rotates, the rack moves in a linear direction. If the mechanism is reversible, the pinion also rotates when the rack moves.
The mechanism transforms rotery motion into linear motion.

· Nut and bolt mechanism.
A nut and bolt mechanism transforms rotary motion into linear motion. It has two parts: a bolt or shaft with a spiral groove and a nut that turns around it.

· Winch and crank mechanism.
A winch is a cylinder that rotates around a horizontal axis. Then we turn the crank to rotate the winch.
The increase in force is proportional to the ratio between the radius of the crank and the radius of the winch

- Reciprocating rotary-linear transformation.
For example, the pedal mechanism of a bycicle transforms the reciprocating movements of our legs into continuous rotary motion.

· Crank and rod mechanism.
The piston moves a rod forwards and backwards. We find cranks and roda in internal combustion engines, as well as windscreen wiper mechanisms.

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

· Cam mechanism.
A cam is an irregularly 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 or it can turn a switch on and off. We can put multiple cams on one shaft, called a camshaft.
Some cams are circular, but with an axis of rotation that is off-centre. These are called eccentric cams because they rotate in an irregular or eccentric way.