Narrow V-Belts — 3V, 5V, 8V

What it is

Narrow V-belts have a deeper, narrower profile than classical belts. More of the belt contacts the groove, so a narrow belt drive can carry the same power with fewer belts or smaller sheaves. They are common on fans, pumps, compressors and crushers. Like classical belts, they run in matched sets on multi-belt drives.

How to identify

The marking gives the section and length, such as 5V1000. A "VX" (3VX, 5VX) means a cogged, raw-edge belt in the same section. Banded versions are marked with the number of ribs, such as 4/5V1000. If the marking is gone, measure the top width and compare to the V-belt cross-section chart.

Section and length decoding

The section number is the nominal top width in eighths of an inch. The length number is the effective (outside) length in tenths of an inch. Divide by ten to get inches.

Key points

• Narrow belts need narrow-section sheaves. Groove angles and depths differ from classical sheaves.
• Some combination sheaves accept both a classical and a narrow section, but only the pairs the maker lists.
• Replace all belts in a set at once. Use matched or "matching-free" belts as the maker directs.
• Cogged 3VX and 5VX belts handle smaller sheave diameters than the wrapped versions.
• Banded belts stop belt whip and turnover on long or pulsing drives.
• Check groove wear with a gauge and tension by the maker's method.

Common mistakes

• Treating a 5V belt as a B belt because the top width looks close. The depth and groove angle differ.
• Reading 5V1000 as 1000 in long.
• Mixing narrow and classical belts on one drive.
• Running a new belt set in worn sheaves.

Governing standards: ARPM IP-22 (narrow multiple V-belts); ISO 4184 (V-belt lengths). See the V-belt cross-section chart for widths and heights.

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.