A section V-belts are the lightest standard industrial cross section, with a 1/2" top width and 5/16" depth. They handle drives from approximately 1/4 HP to 10 HP and are one of the two most commonly stocked V-belt sections (along with B section). A section belts are widely used on small pumps, fans, compressors, machine tools, shop equipment, and light industrial drives across every industry.
Texas Belting stocks A section V-belts in both wrapped (A) and cogged (AX) construction from Gates, Continental, Bando, and Diesel Belting. Same-day shipping on stocked lengths from Houston.
A (Wrapped) vs. AX (Cogged)
Both A and AX belts have identical cross-section dimensions (1/2" x 5/16") and fit the same A-groove sheaves. The difference is construction: AX has raw rubber sidewalls with molded cogs on the underside. AX is a direct drop-in upgrade for A with no sheave changes.
| Feature | A (Wrapped) | AX (Cogged) |
|---|---|---|
| Construction | Fabric cover on all surfaces | Raw edge sidewalls, molded cogs on underside |
| Minimum sheave OD | 3.0" | 2.2" (allows smaller sheaves) |
| Flexibility | Standard | Higher. Better on small sheaves and tight bends. |
| Heat dissipation | Standard | Better. Cogs increase cooling surface area. |
| Service life | Standard | 20-30% longer on most drives |
| Efficiency | 94-96% | Up to 2% higher |
| Cost | Lower | 10-20% higher (offset by longer life) |
| Sheave | A groove | Same A groove. Fully interchangeable. |
Recommendation: For any A-section drive where the belt is being replaced, AX cogged is the better choice. The longer life and improved efficiency more than offset the slight cost premium. The improvement is most dramatic on drives using sheaves near the 3.0" minimum for wrapped A belts.
A Section Part Number Guide
| Part Number | Type | Inside Length | Outside Circ. |
|---|---|---|---|
| A21 | Wrapped | 21" | 23" |
| AX21 | Cogged | 21" | 23" |
| A36 | Wrapped | 36" | 38" |
| AX36 | Cogged | 36" | 38" |
| A45 | Wrapped | 45" | 47" |
| AX45 | Cogged | 45" | 47" |
| A51 | Wrapped | 51" | 53" |
| A68 | Wrapped | 68" | 70" |
| AX68 | Cogged | 68" | 70" |
| A75 | Wrapped | 75" | 77" |
| A90 | Wrapped | 90" | 92" |
| A120 | Wrapped | 120" | 122" |
How to calculate: A section part numbers use inside length. Measure outside circumference (OC) and subtract 2 to get the part number. OC 70" minus 2 = A68 or AX68.
Most Common A Section Lengths
These are the A and AX belt lengths that Texas Belting stocks most heavily, based on demand across our industrial customer base:
| Length Range | Common Part Numbers | Typical Applications |
|---|---|---|
| Short (21" to 35") | A21, A22, A26, A28, A30, A33, A35 | Bench grinders, small compressors, shop tools, small pumps |
| Medium (36" to 60") | A36, A38, A42, A45, A48, A51, A55, A58, A60 | General light industrial, HVAC, small fans, machine tools, drill presses |
| Long (61" to 90") | A62, A64, A68, A71, A75, A78, A80, A85, A90 | Larger pumps, agricultural drives, industrial fans, conveyors |
| Extra long (91" to 158") | A96, A100, A105, A112, A120, A128, A144, A158 | Long center distance drives, agricultural equipment, large machines |
A section belts are available in lengths from A20 to A158 (and sometimes beyond). AX cogged equivalents are available in most popular lengths. If you need a length not listed, call 888-203-2358 and we will check availability or source it.
Common Applications for A Section V-Belts
| Application | Typical HP | Wrapped or Cogged? |
|---|---|---|
| Small centrifugal pumps | 1/2 to 5 HP | Either. AX preferred for continuous duty. |
| Small air compressors (reciprocating) | 1 to 5 HP | AX recommended. Pulsating loads generate heat. |
| HVAC blowers (residential/light commercial) | 1/2 to 3 HP | Either. Many HVAC units use A or AX. |
| Bench grinders and drill presses | 1/4 to 1 HP | Wrapped (A) is standard on most shop tools. |
| Band saws and scroll saws | 1/2 to 2 HP | AX recommended for small pulleys on woodworking tools. |
| Small conveyors and feeders | 1/2 to 5 HP | Either. AX for high-speed or continuous operation. |
| Lawn and garden equipment | Under 5 HP | Wrapped (A) is standard. Specific lengths for mower decks. |
| Agricultural equipment (light duty) | 1 to 10 HP | Either. Dusty conditions favor AX for heat resistance. |
| Textile machinery | 1 to 5 HP | Wrapped (A) is standard on legacy spinning and weaving drives. |
When to Move Up from A Section
If your A-section drive is experiencing belt slip, overheating, or premature belt failure, the drive may be overloaded for the A cross section. Before increasing belt width, first check tension and sheave condition. If the belt and sheaves are in good condition but the belt still cannot handle the load, consider these upgrade paths:
- Stay on A-groove sheaves: Switch from A wrapped to AX cogged for better grip, cooler running, and longer life on the same drive.
- Add a second belt: If your sheaves are multi-groove, adding a second A or AX belt doubles the drive's capacity.
- Move to B section: If the drive exceeds 10 HP or consistently overloads A-section belts, B section (5/8" wide, up to 25 HP) is the next step up. Requires new sheaves.
- Move to 3V narrow wedge: For compact new designs, a 3V narrow wedge belt (3/8" wide) transmits more power than A in a smaller envelope. Requires 3V sheaves.
See our V-Belt Selection Guide for more help choosing the right belt type for your drive.
Frequently Asked Questions
A section V-belts are 1/2" (12.7 mm) top width and 5/16" (8 mm) deep. This is the smallest standard industrial V-belt cross section, covering drives from approximately 1/4 HP to 10 HP. AX cogged belts have the same dimensions with raw edge sidewalls and molded cogs.
Measure the outside circumference (OC) by wrapping a tape around the top surface of the belt. Subtract 2 to get the inside length, which is the part number. Example: OC 70" minus 2 = A68 (wrapped) or AX68 (cogged).
Both are 1/2" x 5/16" and a 4L physically fits in an A-groove sheave. However, 4L is built to lighter FHP (fractional horsepower) standards and is not rated for the same industrial loads. Use 4L only on drives under 1 HP. For any drive rated 1 HP or above, use A or AX.
For A wrapped belts, the minimum recommended sheave outside diameter is 3.0". For AX cogged belts, the minimum is 2.2". Running a belt on a sheave smaller than the minimum causes excessive bending stress that leads to cracking and premature failure. If your sheaves are near or below 3.0", switching to AX cogged extends belt life significantly.
Yes. A section is one of the two most heavily stocked V-belt sections at Texas Belting (along with B). We carry both A and AX in the most popular lengths from Gates, Continental, Bando, and Diesel Belting. In-stock belts ship same day from Houston. Call 888-203-2358 to check availability on your specific length.
V-Belt Drive Components
A and AX belts require A-groove sheaves. The sheave groove must match the belt section. Browse our V-belt drive components, or see our Sheave Selection Guide for help choosing the right one.
Related Pages
Need an A or AX V-Belt?
Texas Belting stocks A and AX section V-belts in all popular lengths from multiple manufacturers. Send us your part number or outside circumference measurement and we will match it.
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