ROTARY-LINEAR TRANSFORMATION

Wheel: wheels are essential parts of bicycles. They let us more easily because they reduce our contact with the ground and decrease friction.
With each rotation, a wheel moves forward a distance that is equal to its circumference (2πr)
Rack and pinion mechanism: The rack is a bar with many teeth and the pinion is a gear with teeth that interlock with the rack. It transforms rotary motion into linear motion.
But and bolt mechanism: It has two parts: a bolt with spiral groove and a but that turns around it.
Winch and crank mechanism: A winch is a cylinder that rotate around a horizontal axis. We attach a rope to the winch and to a load. The increase in force is proportional to the ratio between the radius of the crank and the radius of the winch:
Fxd= Rxr.