The mechanism that transmits rotation using a belt mounted on two shafts (pulleys) and provides a flexible connection between them is called "belt transmission". These processes occur due to the occurrence of friction forces between the pulleys and the belt strip stretched between them. This type of power transmission is one of the oldest types of power traction.
According to the type of belt used, belt transmission can be carried out using a round, flat, toothed rectangular or wedge-shaped belt. The materials from which the belt can be made are quite diverse: leather, cotton, rubberized fabric, etc.
The principle of operation is as follows: there are two shafts and a drive belt stretched between them. The pulley from which the action is transmitted is called the drive shaft, and the one to which the thrust comes is called the driven. The part of the belt that goes to the drive pulley has a stronger degree of tension than that going to the driven pulley. Therefore, the gear ratio of a belt drive is the difference in the degree of tension of these two parts of one belt. Thanks to this indicator, it is possible to determine the thrust coefficient of the drive mechanism.
However, there are a number of peculiarities here. For example, the belt tension must be constantly maintained within the specified limits, since exceeding this value can lead to a break in the belt tape, and excessively low tension, on the contrary, will lead to belt sagging, slippage may occur. The main function that a belt drive performs is a flexible connection between two electric drive shafts without any rigid joints. At the same time, the same force should be transmitted at each moment of time.
If there is a sufficiently large distance between the pulleys, then the belt drive may be subject to significant elastic deformations. This entails stretching the belt and, as a result, its sagging. Therefore, in such situations, the belt can be made of several components, which (due to their small size) will experience less stretching.
The efficiency of a belt drive is determined as follows. It is necessary to divide the power received at the output by the power that came to the drive, and multiply the resulting number by 100%. Belt drive can also be characterized by the amount of losses, on which the power on the driven shaft of the drive directly depends.
Belt transmission has the following advantages: low cost, low noise pollution, smoothness, no lubrication, easy installation and others. Disadvantages - significant dimensions, the possibility of slippage, fragilityand low bearing capacity.
Belt drive performance is increased if slippage is eliminated. This parameter depends on the wrap angle and belt tension.
Girth angle - the central angle that tightens the arc formed at the points of contact between the belt and the pulley.