V – BELT DRIVE
Done & Presented By
. J.A. Ashwin John (31006114009)
. P. Rangaraj (31006114033)
. Varun Bengani (31006114046)
. A. Vijayasarathy (31006114048)
. Project Guide: Mr. N. Senthilnathan, B.E., M.E., MBA
. Presented at- MNM Jain Engineering College,
Belts are the cheapest utility for power transmission between shafts that may not be parallel. Power transmission is achieved by specially designed belts and pulleys. The demands on a belt drive transmission system are large and this has led to many variations on the theme. They run smoothly and with little noise, and cushion motor and bearings against load changes, albeit with less strength than gears or chains. However, improvements in belt engineering allow use of belts in systems that only formerly allowed chains or gears.
V belts (also known as V-belt or wedge rope) solved the slippage and alignment problem. It is now the basic belt for power transmission. They provide the best combination of traction, speed of movement, load of the bearings, and long service life.
Drive commences by the power source applying a torque to the shaft of the small drive pulley, causing it to rotate at a steady speed n1. The tension in the 'tight' upper straight strand will then exceed while the tension in the 'slack' lower strand will become less than. This tension difference applies a torque to the drive load pulley, equilibrating the load torque, while the pulley rotates at uniform speed n2, thus transmitting the power to the load pulley shaft.
A Belt is a looped strip of flexible material, used to mechanically link two or more rotating shafts. They may be used as a source of motion, to efficiently transmit power, or to track relative movement. Belts are looped over pulleys. In a two pulley system, the belt can either drive the pulleys in the same direction, or the belt may be crossed, so that the direction of the shafts is opposite. As a source of motion, a conveyor belt is one application where the belt is adapted to continually carry a load between two points.
Belts normally transmit power on the tension side of the loop. However, designs for continuously variable transmissions exist that use belts that are a series of solid metal blocks, linked together as in a chain, transmitting power on the compression side of the loop.
The open belt drive has parallel shafts rotating in the same direction, whereas the cross-belt drive also bears parallel shafts but rotate in opposite direction. The former is far more common, and the latter not appropriate for timing and standard V-belts, because the pulleys contact both the both inner and outer belt surfaces. Nonparallel shafts can be connected if the belt's center line is aligned with the center plane of the pulley. Industrial belts are usually reinforced rubber but sometimes leather types, non-leather non-reinforced belts, can only be used in light applications.
The great majority of mechanical power transmission applications involve rotating shafts, since rotation is continuous and the shafts / mountings are cheap relative to other means of power transmission. Matching a prime- mover to a load thus involves transformation of power between shafts - usually from a high speed / low torque drive shaft, through a speed reducer of ratio R ≥ 1, to a low speed / high torque load shaft.
As has been noted, speed reducers are employed almost invariably to amplify torque rather than to reduce speed. The two most common speed reduction mechanisms in industry are belts (usually...