Reciprocating rotary-linear transformation

Crank and rod mechanisms 

This mechanisms was important for the first steam engines. Today we find cranks and rods in internal combustion engines, as well as windsceen 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. We use crankshaft for combustion motors that use pistons. We also use them for sewing machines.

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 or it can turn a switch on and off. In some mechanisms, a spring pushes the follower back to its original position. We can find camshaftsin toys, automatic tools and combustion motors. There are often eccentric cams in sewing machines and other devices that transform rotary motion to linear motion.

Rotary-linear transformation

Wheel

Wheels are essential parts of bicycles. They let us move more easily because they reduce our contact with the ground and decrease friction. However, if there isn't enought friction, the wheels can slide out of control.  

Rack and pinion mechanisms
A rack and pinion mechanisms 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 mechanisms is reversible, the pinion also rotates when the rack moves..






Nut and bolt mechanism
A nut and bolt mechanisms transforms rotary motion  into linear motion. It has two parts: a bolt or a shaft with a spiral groove and a nut that turns around it. We can use a nut and bolt mechanism to lift loads because it funtions as a reducing system.








Whinch and crank mechanism 
A whinch is a cylinder that rotates around a horizontal axis. We attacha rope to the tothe winch and to a load. Then we turn the crank to rotate the winch. We use winches for lifting loads. We find them in cronstruction cranes and in the mechanism that raises window blinds in our homes.

Worm drive

A worm drive reduces the speed of a rotary system very effectively. A worm drive has two parts: a worm shaft and a worm gear. The saft has two, three or even more grooves.Each groove interlocks with one tooth of the worm gear.

                                     

Idler gear

In a simple two-gear system, the gears turn in opposite directions. If we want the gears to turn in the same direction, we put an idler gear between them. This gear changes the direction of rotation, but it doesn't change the ratio of tramsmission.

Rotary transmission

Rotary transmission systems put two rotating elements into contact. These mechanisms have two purposes:

• Transferring rotary force from an input location to another location.
• Changing the rotary speed by using rotating elements of different sizes.

We can perform these functions with various mechanisms, such as the following:

Pulleys and compound pulley systems

In a system of pulley, the equilibrium between the forces depends on the path that the rope follows.

Pulleys

 A pulley is a wheel that rotates around an axis and has a groove. We can divide pulleys into two basic types:

Compound pulley systems

Is a combination of fixed and movable pulleys. It ia also called a block and tackle system. We can combine the pulleys in various ways: