RECIPROCATING ROTARY-LINEAR TRANSFORMATION

Crank and rod mechanism: parts: wheel, rod, crank, piston and steam engine.
The piston moves a rod forwards and backwards. This rod turns the first wheek and the second wheel turns because it is connected to the first wheel by another rod.

Crankshaft mechanism: we can connect multiple rods to one shaft, the rods are connected  to cranks and the cranks are connected to the crankshaft. A crankshaft mechanism can synchronise the movements of various parts.
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.

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.

WORM DRIVE

A worm drive reduces the speed of a rotary system very effectively. The worm drive has two parts: a worm shaft and a worm gear.
The shaft had two, three or even more grooves. Each groove interlocks with one tooth of the worm gear.
When the worm shaft makes a rotation, the worm gear moves forward one tooth for every groove of the shaft.

CHANGES IN DIRECTION AND ROTATION

With belts, we can change the direction of rotation and the axis of rotation quite easily.
We can use different types of gears when two axes are parallel, perpendicular or crossed.

BELT DRIVES AND GEAR TRAINS

A belt drive is a system of pulleys connected by belts.
Each belt connects a pair of pulleys, so they turn together.
A gear train is a system of interconnected gears.
To calculate the ratio transmission between the first wheel and the last of a belt drive, we must multiply the ratios of transmission  of the first pair of wheels and the second pair of wheels:
N4/N1= D1 x D3/ D2 x D4
N is the speed of rotation and D is the diameter of the wheel.
If  is a gear train, we make these calculations using the number of cogs or teeth (Z). Belt drive. Gear train.