A Belt is used to transmit the crankshaft power to other accessories that depend on engine power.
A Belt is required to transfer some of the engine power to other dependent accessories without slipping.
A belt as mentioned is used to transmit the power by traveling over the pulleys. It is made up of flexible material and uses crankshaft power to make other accessories operate.
Belts usually comes in following types: Flat belts which is used when high power at high speed is necessary, Round belts which are used when low torque is required, V belts are used when traction, speed of movement, load of the bearings, and long service life is required and it also avoid the misalignment and slippage difficulty, Multi-groove (Serpentine Belts) belts have very thinner edge which reduces the friction and thus the energy wasted. Film belts are generally used for low-power (10 hp or 7 kW), high-speed uses and gives high efficiency (up to 98%) and long life. Timing belts have no slippage and run at constant speed. They are often used to transfer direct motion.
A Belt is one of the oldest and still used power transmission techniques in automobiles. Being flexible in nature, a belt can transmit the power easily from the crankshaft to the accessories that depend on the engine power. Made up flexible material usually rubber, the belt is a closed loop that rotates around the crankshaft and other accessories like alternator, fuel pump etc. along with it. Transmission belts used in automobiles can transmit the power easily even if the shafts are not aligned axially and have transmission efficiency of 90-95% depending on the type of belt used. Usually a V-type belt is used in most of the vehicle makes as its side faces have ability to generate better friction due to wedging action. Although belts are simple and inexpensive with an ability to run smoothly with little noise, they possess less strength and efficiency compared to chains and gears which are considered as positive drives. In addition the belt is subjected to different tensions on both the sides in case of open belt drive which causes the belt to develop creep and give rise to slipping. For a belt it is also important that the friction should not be generated in excess amount as it may affect the belt tension and contact angle giving rise to rapid wear.