How to Read a V-Belt Part Number: A68, BX75, 5V1060, SPZ1000 Explained

A V-belt fails on your conveyor at 6am and the only marking on it is "B75." You need to know what that means before you call your supplier. This guide covers every major V-belt designation system so you can identify what you have, find the cross-reference, and order the right belt the first time.

Two Systems, One Principle

North American equipment uses the classical imperial system: A, B, C, D sections for standard belts, plus 3V, 5V, 8V narrow wedge for higher-power compact drives. European and imported equipment uses the ISO metric system: SPZ, SPA, SPB, SPC. If you're maintaining a German compressor or Italian pump, this is what you're dealing with. Both systems encode the same two things: the cross-section profile and the belt length. Learn the pattern once and you can read any part number.

Classical V-Belts: A, B, C, D

Format: letter then number. A68, B75, C120, D180. The letter is the cross-section. A is 1/2" wide, 5/16" deep. Light duty: HVAC fans, small compressors, auxiliary drives. B is 5/8" wide, 13/32" deep. This is the most common section in general plant maintenance. Pumps, fans, blowers, most standard industrial drives. C is 7/8" wide, 17/32" deep. Heavy industrial: large compressors, high-torque drives, multi-belt setups. D is 1-1/4" wide, 3/4" deep. Heavy duty drives where C-section isn't enough. The number is the inside circumference in inches. B75 is a B-section belt with a 75-inch inside circumference. That's it. Every manufacturer makes these to the same dimensions. A Gates B75, a Dayco B75, a Bando B75 are interchangeable. The belt profile and length are standardized. What differs between brands is rubber compound and cord quality, not fit. Search B75 on Partmatch to see all brands with pricing.

Cogged Belts: AX, BX, CX

Same dimensions as classical belts, different construction. The molded notches on the inner surface make the belt more flexible, run cooler, and last longer on small-diameter sheaves. Format: letter plus X, then number. AX68, BX75, CX120. An AX68 fits the same sheave as an A68. Drop-in replacement, better performance. If you're replacing classical belts on a drive with sheaves under 3.5 inches, switch to cogged. On larger sheaves the difference is marginal.

Narrow Wedge: 3V, 5V, 8V

These belts move more power than classical sections in a smaller package. Common on industrial compressors, pumps, and equipment where the drive has to be compact.

Format: section then number. 3V400, 5V1060, 8V1600. The number is the outside circumference in tenths of an inch. 5V1060 is a 5V-section belt with a 106.0-inch outside circumference. Divide by 10 to get inches.

This is where people get tripped up. Classical belts use inside circumference. Narrow wedge belts use outside circumference. Order a 5V using inside circumference and you'll get a belt that's too short. Double-check which measurement system applies before you call your supplier.

3V is 3/8" wide, light to medium loads. 5V is 5/8" wide, the most common narrow wedge in industrial maintenance. 8V is 1" wide, high-power heavy duty drives.

One more thing: a 5V belt does not fit a B-section sheave even though both are 5/8" wide. The groove angles are different. B-section sheaves have a 38-degree included angle. 5V sheaves have a 36-degree angle. Close but not interchangeable. Wrong combination causes the belt to ride too high or too low in the groove and it wears out fast. Check your sheave specification before substituting.

Search 5V1060 on Partmatch for all brands.

Cogged Narrow Wedge: 3VX, 5VX

Same relationship as AX to A. Cogged construction on a narrow wedge profile. Better heat dissipation, better flexibility on smaller sheaves.

Format: section plus X, then number. 3VX355, 5VX800.

Fits the same sheaves as 3V and 5V. If you're running hot or have small sheaves, this is the right upgrade. Search 5VX800 on Partmatch.

Metric Belts: SPZ, SPA, SPB, SPC

You'll find these on European equipment and increasingly on imported industrial machinery. The format is straightforward once you know it.

Format: section then length in millimeters. SPZ1000, SPA1500, SPB2000, SPC3000. The number is always the outside circumference in millimeters. No conversion needed. SPZ is 10mm wide, light duty. SPA is 13mm wide, equivalent in power capacity to an A-section. SPB is 17mm wide, the most common metric section in plant maintenance. SPC is 22mm wide, heavy duty.

Do not substitute SPB for B-section or SPA for A-section. The groove angles differ and the belt will not seat correctly. If your machine takes an SPB, order an SPB. Cross-reference between SPB brands is fine: Gates SPB, Continental SPB, Optibelt SPB are all interchangeable. Search SPB2000 on Partmatch for pricing across brands.

The One Mistake That Causes Wrong Orders

Inside circumference versus outside circumference.

Classical belts: A, B, C, D, AX, BX, CX — inside circumference in inches. Narrow wedge belts: 3V, 5V, 8V, 3VX, 5VX — outside circumference, divide by 10 for inches. Metric belts: SPZ, SPA, SPB, SPC — outside circumference in millimeters.

Get this wrong and your belt is either too short to install or too long to tension properly. When in doubt, measure both inside and outside circumference of the old belt and tell your supplier both numbers.

Cross-Referencing Between Brands

Once you have the section and length, finding an equivalent from another brand is straightforward. All manufacturers build to the same dimensional standards within each system.

The rubber compound, cord material, and manufacturing tolerances vary between brands. Gates and Bando are both premium. Dayco and Continental are solid. Budget brands will fit but often run hotter and wear faster on demanding drives. For a light-duty HVAC fan, brand matters less. For a compressor running 16 hours a day, buy Gates or Bando. Search any belt part number on Partmatch and get the verified cross-reference across Gates, Dayco, Bando, Continental, and Optibelt with pricing.

Quick Reference A68: classical A-section, 68" inside circumference. Search A68 BX75: cogged B-section, 75" inside circumference. Search BX75 5V1060: narrow wedge, 106.0" outside circumference. Search 5V1060 5VX800: cogged narrow wedge, 80.0" outside circumference. Search 5VX800 SPB2000: metric wedge, 2000mm outside circumference. Search SPB2000

Search any V-belt part number on Partmatch to find cross-references across Gates, Dayco, Bando, Continental, and Optibelt with pricing.