A drive belt, in machinery, a pair of pulleys attached to usually parallel shafts and connected by an encircling flexible belt (band) that can serve to transmit and modify rotary motion from one shaft to the other.
Belts are looped over pulleys and may have a twist between the pulleys, and the shafts need not be parallel. Most drive belts consist of flat leather, rubber, or fabric belts running on cylindrical pulleys or of belts with a V-shaped cross-section running on grooved pulleys.
There are Seven different types of drive belt can be found and those are:
1. Open Drive Belt
The open drive belt is used with shafts arranged parallel and rotating in the same direction. In that case, the driver pulls the belt from one side and delivers it to the other side.
Thus, the tension in the lower side belt will be higher than the upper side belt. The lower side belt is known as the tight side belt while the upper side belt is known as the slack side belt.
2. Closed Or Crossed Drive Belt
Cross or twisted drive belts are used with rotating shafts in parallel and opposite directions. In this case, the driver pulls the belt from one side and delivers it to the other side.
3. Fast And Loose Cone Pulley
This type of drive belts is used when the driven or machine shaft is to be started or stopped whenever desired without interfering with the driving shaft. A pulley which is keyed to the machine shaft is called a fast pulley and run at the same speed as that of the machine shaft.
A loose pulley runs freely over the machine shaft and is incapable of transmitting any power. When the driven shaft is required to be stopped, the belt is pushed on to the loose pulley by means of a sliding bar having belt forks.
4. Stepped Cone Pulley Drive
A step or cone pulley drive is used to change the speed of the driven shaft, while the main or driving shaft moves at a constant speed. This is accomplished by shifting the belt from one part of the steps to another.
A step cone pulley is an integral casting consisting of three or different numbers of different sizes of pulleys adjacent to each other, as shown in fig. A set of driven cone pulleys is placed upside down on the drive shaft. An endless belt will be wrapped around a pair of pulleys.
5. Jockey Pulley Drive.
In an open drive belt arrangement, if the center distance is small, or if the driven pulley is too small, the arc of the belt’s contact with the driven pulley will be very small, which reduces the tension in the belt, or if the belt requires Stress cannot be achieved by other methods, a sluggish pulley, called a jockey pulley, is placed on the slack side of the belt as shown in fig.
6. Quarter Turn Drive Belt
Quarter turn drive belts are also known as right-angle drive belts. It is used with shafts arranged at right angles and rotating in a certain direction. To prevent the belt from leaving the pulley, the width of the face of the pulley must be greater than or equal to 1.4 b, where b is the width of the belt. If the pulley cannot be arranged or when reversible speed is desired, a quarter-turn drive belt with a guide pulley may be used.
7. Compound Drive Belt
A compound drive belt is used when power is passed from one shaft to another through multiple shafts.
This article comes from engineering edit released