V Belt

The Common Types of V-Belts

When we want to transfer power from one shaft to another, we use power transmission devices, such as belts, chains and gears. In today's article we will discuss a highly flexible and efficient  power transmission device known as V-belt. V-belts get their name from their trapezoidal shape, which helps them wedge into the sheaves.Twisted synthetic fibrous tensile chords, compressed by synthetic rubber, form a typical V-belt, rendering it strength and flexibility. To break the bending resistance even further, to keep the operation temperature lower, and to give higher capacity, V-belts come in cogged construction as well. As opposed to chains, V-belts do not require lubrication or maintenance. They also solve the slippage and alignment problems.


The types of V-belts and their standard sizes:


There are three common V belt types: Classical V-belt (classified by their dimensions from A to E), Narrow V series (classified by their dimensions 3V, 5V, and 8V), and light duty Fractional Horsepower belt (classified by their dimensions 2L, 3L, 4L, 5L). Their counterpart cogged belt is classified by the letter X. For example, Classical V cog belt will be 3VX, 5VX, ect. 


Classical V-belt:


Conventional V-belt is the most common V-belt type and has been around the longest. The Initial classical V design replaced leather belts by taking over their applications in a wide range of industries, such as agriculture, ventilation, and industrial machinery. Classical V-belts are capable of covering a load range from fractional(less than 1 HP) to 500 horsepower. They are less efficient than narrow V-belt and generally contribute to higher bearing loads. However, classical V-belts have high tolerance for poor operating conditions.

The general part number format is the cross section size and the inside length in inches ( e.g. B50 is a B section of 50 inches inside length ).

General cross sectional dimensions that are used in the US are shown below.   

Classical v belt dimensions sizes

Narrow V series:


Narrow belts are optimum for load transfer and force distribution because of their greater depth to width ratio. That’s their advantage over classical V belts. Narrow belts are also suitable for drives with high belt speeds, again, for their powerfully compact size. Narrow belts have the ability to transmit up to three times the horsepower of classical V-belt in the same drive space. They can handle drives from 1 to 1000 horsepower.

Part number designation for wedge belts are shown in terms of belt top width followed by nominal outside length in inches. The numerical prefix indicates the belt top width in one eighth of an inch. For example 5V500 part number indicates 5/8” top width with 50.0” outside length.

General cross sectional dimensions that are used in the US are shown below.


Wedge narrow v belt dimensions sizes


Fractional Horsepower Belt:


FHP light duty V-belts are used most often as single belt on drives of 1 horsepower or less. Its design is for relatively light loads. The common applications for this V-belt type are domestic washing machines, small fans, refrigerators, and garage equipment. Light V-belts should never be used on any heavy-duty industrial applications, even if they seem to fit the classical or narrow V-belt pulley grooves.

Part number designation for FHP belts are similar to wedge. They are identified with a 2L, 3L, 4L or 5L prefix. The numerical prefix indicates the belt top width in one eighth of an inch followed by nominal outside length in inches. For example 3L300 part number indicates 3/8” top width with 30.0” outside length.

General cross sectional dimensions that are used in the US are shown below.

Fractional Horspower V belt dimensions sizes FHP


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