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
| System | Used For | Sections |
|---|---|---|
| Classical Imperial | North American equipment | A, B, C, D + 3V, 5V, 8V narrow wedge |
| ISO Metric | European and imported equipment | SPZ, SPA, SPB, SPC |
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. The number is the inside circumference in inches.
| Section | Top Width | Depth | Typical Use |
|---|---|---|---|
| A | 1/2" | 5/16" | Light duty: HVAC fans, small compressors, auxiliary drives |
| B | 5/8" | 13/32" | Most common in plant maintenance: pumps, fans, blowers, standard industrial drives |
| C | 7/8" | 17/32" | Heavy industrial: large compressors, high-torque drives, multi-belt setups |
| D | 1-1/4" | 3/4" | Heavy duty drives where C-section isn't enough |
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.
| Section | Width | Typical Use |
|---|---|---|
| 3V | 3/8" | Light to medium loads |
| 5V | 5/8" | Most common narrow wedge in industrial maintenance |
| 8V | 1" | 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.
| Sheave Type | Included Angle |
|---|---|
| B-section | 38° |
| 5V | 36° |
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.
Format: section then length in millimeters. SPZ1000, SPA1500, SPB2000, SPC3000.
The number is always the outside circumference in millimeters. No conversion needed.
| Section | Width | Typical Use |
|---|---|---|
| SPZ | 10mm | Light duty |
| SPA | 13mm | Equivalent in power capacity to an A-section |
| SPB | 17mm | Most common metric section in plant maintenance |
| SPC | 22mm | 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.
| Belt Type | Length Convention |
|---|---|
| Classical (A, B, C, D, AX, BX, CX) | Inside circumference in inches |
| Narrow wedge (3V, 5V, 8V, 3VX, 5VX) | Outside circumference, divide by 10 for inches |
| Metric (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.
| Tier | Brands | Use Case |
|---|---|---|
| Premium | Gates, Bando | High-load, continuous duty (compressors running 16+ hours/day) |
| Solid | Dayco, Continental | General industrial maintenance |
| Budget | Various | Light-duty applications, HVAC, intermittent use |
The rubber compound, cord material, and manufacturing tolerances vary between brands. Search any belt part number on Partmatch and get the verified cross-reference across Gates, Dayco, Bando, Continental, and Optibelt with pricing.
Quick Reference
| Part Number | Type | Length | Search |
|---|---|---|---|
| A68 | Classical A-section | 68" inside circumference | A68 |
| BX75 | Cogged B-section | 75" inside circumference | BX75 |
| 5V1060 | Narrow wedge | 106.0" outside circumference | 5V1060 |
| 5VX800 | Cogged narrow wedge | 80.0" outside circumference | 5VX800 |
| SPB2000 | Metric wedge | 2000mm outside circumference | SPB2000 |
Search any V-belt part number on Partmatch to find cross-references across Gates, Dayco, Bando, Continental, and Optibelt with pricing.
For specific belt conversion guides, see: