Classical V-Belts — A, B, C, D, E

What it is

Classical V-belts are the original industrial multiple-belt sections. Each belt is a trapezoid of rubber with tension cords and a fabric or raw-edge cover. They wedge into sheave grooves and transmit power by friction. Many drives use several belts side by side, which must be a matched set.

How to identify

Read the belt marking. The letter gives the section and the number gives the length. An "X" after the letter (AX, BX, CX) means a cogged or notched belt with the same section. Banded belts join several belts with a common top band and are marked with the number of ribs, such as 3/B60. If the marking is gone, measure the top width and the thickness and compare to the V-belt cross-section chart.

Decoding classical belt numbers

For classical belts the length number is usually close to the inside length in inches. The pitch and outside lengths are longer by an amount that depends on the section. The exact relationship is in ARPM IP-20 and the maker's catalog.

Key points

• Section sizes, from smallest to largest: A, B, C, D, E. Top widths and heights are on the V-belt cross-section chart.
• Replace all belts on a multi-belt drive at the same time. Mixing new and used belts overloads the new ones.
• Cogged belts bend more easily and run cooler on small sheaves. They fit the same grooves as the wrapped belt of the same section.
• Classical and narrow belts use different groove profiles. Do not mix them on one drive.
• Check sheave grooves with a groove gauge. Worn, dished grooves let belts bottom out and slip.
• Tension by the maker's method (deflection force or a sonic tension meter), not by feel.

Common mistakes

• Replacing one belt in a set.
• Using an A belt as a 4L belt, or the reverse. They differ in length reference.
• Running classical belts in narrow-section sheaves.
• Dressing belts to stop slip instead of finding the cause.

Governing standards: ARPM IP-20 (classical multiple V-belts); ISO 4184 (classical and narrow V-belt lengths). See the V-belt cross-section chart.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.