Belt Tensioner
A belt tensioner is exactly that – a device that maintains the tension in a belt. The belts are attached to pulleys and looped around other devices in order to keep them running. The principle is the same as that of a bicycle chain, which transfers motion from the pedals to the wheels of the bike. The belts transfer power to the steering system, water pumps, air pump, air conditioner and alternator from the drive pulley of the engine.
Belt tensioners are mostly used in automotive engines, in particular cars, which have several different types of belts. Commonly used in cars are the V belts, Timing belts and the Serpentine belts.
V belts are used for the car’s accessories; they are named that because of their appearance, having narrowed outside surfaces and becoming thicker as they taper down. In older cars, multiple V belts were used to drive multiple accessories.
Timing belts connect a car engine’s camshaft to its crankshaft. It is toothed to fit around the sprockets of both the devices and maintains their timing. In some cars the water pumps, oil pumps and balance shaft may also be driven by a Timing belt. Timing belts are important because the cur will not run of they do not work properly.
Serpentine belts are found in most modern cars available in the market today. They are thick and have a wide surface area, and are used to drive almost all of a car’s accessories; the alternator, power steering pump, water pump, air conditioner compressor, and air pump. They are more efficient than multiple belts, and a single serpentine belt is much easier to maintain and replace than several V belts. Also, the disadvantage of multiple belts is that if one of the devices break down, it may take some time for the driver to notice. With a single serpentine belt connecting all the peripheral devices, of one of them break down the whole car will shut down.
The belt tensioner has several functions. Its primary purpose is to keep the belts tight so that they can drive the devices. The tensioner takes away the need to tighten the belts manually. Since the tensioner maintains the proper tension, the accessories attached to the belt last longer. Another function of the belt is to prevent belt slip, which can make the accessories perform poorly and also reduce the service life of the car.
Serpentine belts come with automatic belt tensioners which adjusts the tension in the belt to the correct amount. The tensioner has a spring which exerts the correct amount of force. The tensioner is also designed to compensate for wear and tear, so that no matter how worn the tensioner is, it still exerts the same amount of force. The tensioner also has a plastic or steel pulley, with bearings which must be properly lubricated at all times. Steel pulleys are preferred because of their many advantages over plastic pulleys. The metal deflects dirt and resists abrasion, and their bearings retain their shape despite being pressed into a steel pulley. Since the belt is exposed to a lot of heat, a steel tensioner performs better because metal dissipates heat better than plastic. Plastic pulleys catch dirt and grit, abrading the belt. They retain heat and their bearings are prone to distortion even in the molding stage.
Belt tensioners, like all the other parts of a car, do not last forever. They need to be properly maintained and replaced when needed. In cars that have serpentine belt, it is recommended that the tensioner is replaced when the belt is replaced, for better performance.
