How to measure V Belt sizes and Dimensions

There are more than sixty six (66) various dimensions, sizes and types of belts that are used in the agriculture equipment industry. These various belts are used in tractors, combines, balers, snow blowers, tillers, mowers, harvesters and lawn and garden tractors.

V Belts are used as fan belts, timing belts, alternator belts, drive belts for mowers, and general pulley driven devices found in combines, mowers, balers, harvesters and other agricultural equipment.

To change a cut or damaged V belt, it must first be identified. The fastest and easiest way to identify a belt is to deduce the V belt part number that is written on it.

However, in practice, sometimes this is not possible, and then other methods must be used. The basic V belt has a trapezoidal cross section, with equal sides, and different lengths at the top and bottom. There are five popular (5) basic v belt types (called Classical V Belt), and these are defined as A, B, C, D and E. Models Z and F will not be covered here. Each V Belt can have its part number described by utilizing five key dimensions, namely, the top width pitch width, height, angle and true circumference.

The A model has a top width of 13mm (1/2 inch) and a height of 8 mm (5/16th of an inch).

The B model has a top width of 17mm (21/32nd of an inch) and a height of 11 mm (13/32nd of an inch).

The C model has a top width of 22 mm (7/8th of an inch) and a height of 14 mm (17/32nd of an inch).

The D model has a top width of 32 mm (1 1/4th of an inch) and a height of 19 mm (3/4 of an inch).

The E model has a top width of 38 mm (1 1/2th of an inch) and a height of 23 mm (29/32nd of an inch). All classical belts have angles of 40 degrees.

The other major variant of this component is its length. The normal outside and inside circumference of the belt can be measured. However, for measuring and part number identification purposes, this is not the true circumference. The effective circumference of the belt is the part of the belt that most of the pressure is concentrated on while under word pressures (called pitch length). This line is generally located at the neutral axis near the cord line and varies with cross section and construction. This circumference is typically a few millimeters under the top width of the belt.

Some manufacturers and users prefer the pitch length to identify belts. However, most users tend to use the inner circumference of the belt for identification purposes. For example, a belt with a “C” dimensions and an inner length of ninety five (95) inches will have part number of C95. This description can be used to identify the other types for the A, B, D, Z and E.