Belts and Pulleys of Cars:
A belt is a loop of flexible material used to link two or more rotating shafts, alternator and water body mechanically. It may be used as a source of motion, to transmit power efficiently. They are looped over pulleys and may have a twist between the pulleys, and the shafts which need not be parallel.
In a two pulley system, the belt can either drive the pulleys normally in one direction or the belt may be crossed, so that the direction of the driven shaft is reversed. A conveyor belt is one of the important part
where the belt is adapted to carry a load continuously between two points.

They are simple, inexpensive, and do not require axially aligned shafts. They help to protect machinery from overload and jam, and damp and isolate noise and vibration. Load fluctuations are shock-absorbed. They need no or less lubrication and very minimal maintenance. They have high efficiency about 90-98%, usually 95%, high tolerance for misalignment, and are of relatively low cost if the shafts are far apart. Different speeds can be attained by stepped or tapered pulleys.

The angular-velocity ratio may not be equal to that of the pulley diameters, due to slip and stretch. This problem has been largely solved by the use of toothed belts. Working temperatures of belts ranging from −31 °F to 185 °F. Adjustment of center distance of an idler pulley is crucial to compensate for wear and stretch.

What is Tensioner of a car?

A drive belt tensioner is a mechanical device that applies a force to create or maintain tension. The force may be applied parallel to, or perpendicular to, the tension it creates. The torque may be generated by a fixed displacement, as in the case of an eccentric bicycle bottom bracket, which can be adjusted as parts wear, or by stretching a spring, as in the case of a spring-loaded bicycle chain tensioner; by changing the volume of a gas, as in the case of a marine riser tensioner; by hydraulic pressure, as in the case of a hydraulic belt tensioner; or by gravity acting on a suspended mass, as in the case of a chair lift cable tensioner. In the power sector, the it is a machine for maintaining constant tension of the conductors during work of hanging the transmission network.

Belt tensionersare the device made to apply a specific tension to a belt

• The chain tension of a chainsaw can be adjusted with a chain tensioner.

• A marine riser tensioner is a device used on an offshore drilling vessel which provides constant
upward force on the drilling riser independent of the movement of the floating drill vessel.

• A guideline tensioner is a hydropneumatics device used on an offshore drilling rig that keeps a positive pulling force on the guidelines from the platform to a template..

• Overhead electrical wires may be placed in tension by springs or weights.

• Conveyor belts are also used.

• Chair lift and gondola lift cables are other devices.

• Certain wood trusses, such as the beam tensioner truss.

• Fencing made of wire, such as electric fences, barbed-wire fences, and chain-link fences often include tensioning devices to keep it taut.

• Belt sanders have a mechanism, to apply the proper tension to the sanding belt, which can be released to allow for changing belts.