B section is the most widely used V-belt cross section in North American industry. With a 5/8" top width and 13/32" depth, B section belts cover the 1 to 25 HP range that includes the majority of general industrial drives: HVAC air handlers, compressors, pumps, blowers, conveyors, agricultural equipment, and manufacturing machinery. If a plant maintenance team stocks only one classical V-belt section, it is almost always B.
Texas Belting carries the deepest B section inventory of any belt we stock, in both wrapped (B) and cogged (BX) construction from Gates, Continental, Bando, and Diesel Belting. Same-day shipping on the vast majority of B and BX lengths from our Houston warehouse.
B (Wrapped) vs. BX (Cogged)
Both B and BX belts have identical cross-section dimensions (5/8" x 13/32") and fit the same B-groove sheaves. BX is a direct drop-in upgrade with no sheave changes.
| Feature | B (Wrapped) | BX (Cogged) |
|---|---|---|
| Construction | Fabric cover on all surfaces | Raw edge sidewalls, molded cogs on underside |
| Minimum sheave OD | 5.4" | 4.0" (allows smaller sheaves) |
| Flexibility | Standard | Higher. Reduced bending resistance. |
| 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 | B groove | Same B groove. Fully interchangeable. |
Recommendation: BX cogged is the better choice for any B-section replacement. The 20-30% life extension alone justifies the slight cost premium. For drives running at high speed, in hot environments, or on sheaves near the 5.4" minimum, BX is strongly recommended.
B Section Part Number Guide
| Part Number | Type | Inside Length | Outside Circ. |
|---|---|---|---|
| B35 | Wrapped | 35" | 38" |
| BX35 | Cogged | 35" | 38" |
| B46 | Wrapped | 46" | 49" |
| BX46 | Cogged | 46" | 49" |
| B55 | Wrapped | 55" | 58" |
| B62 | Wrapped | 62" | 65" |
| BX62 | Cogged | 62" | 65" |
| B68 | Wrapped | 68" | 71" |
| BX68 | Cogged | 68" | 71" |
| B75 | Wrapped | 75" | 78" |
| B81 | Wrapped | 81" | 84" |
| B90 | Wrapped | 90" | 93" |
| B100 | Wrapped | 100" | 103" |
| BX100 | Cogged | 100" | 103" |
| B112 | Wrapped | 112" | 115" |
| B128 | Wrapped | 128" | 131" |
| B144 | Wrapped | 144" | 147" |
How to calculate: B section part numbers use inside length. Measure outside circumference (OC) and subtract 3 to get the part number. OC 103" minus 3 = B100 or BX100.
Most Common B Section Lengths
| Length Range | Common Part Numbers | Typical Applications |
|---|---|---|
| Short (30" to 50") | B30, B33, B35, B38, B40, B42, B44, B46, B48, B50 | Small compressors, pumps, machine tools, light conveyors |
| Medium (51" to 80") | B51, B55, B58, B60, B62, B64, B68, B71, B75, B78, B80 | HVAC air handlers, general industrial, agricultural, blowers |
| Long (81" to 120") | B81, B85, B88, B90, B95, B100, B105, B112, B120 | Large air handlers, heavy conveyors, industrial fans, compressors |
| Extra long (121" to 300") | B128, B136, B144, B158, B173, B195, B210, B240, B270, B300 | Long center-distance drives, agricultural combines, large industrial equipment |
B section belts are available in lengths from B25 to B300+. BX cogged equivalents are available for the most popular lengths. Texas Belting stocks the broadest B section inventory in Houston. Call 888-203-2358 for availability on any length.
Common Applications for B Section V-Belts
| Application | Typical HP | Wrapped or Cogged? |
|---|---|---|
| HVAC air handlers and rooftop units | 1 to 15 HP | Either. BX preferred for warm mechanical rooms and continuous duty. |
| Reciprocating air compressors | 3 to 25 HP | BX strongly recommended. Pulsating loads and heat. |
| Centrifugal pumps | 1 to 20 HP | Either. BX for continuous duty and hot-environment pumps. |
| Industrial fans and blowers | 3 to 25 HP | BX recommended. High speed and continuous operation. |
| Agricultural equipment | 1 to 25 HP | B is standard. BX in dusty, hot conditions for longer life. |
| Package handling conveyors | 1 to 15 HP | Either. Multi-belt drives are common on wider conveyors. |
| Food processing equipment | 1 to 15 HP | BX recommended for washdown-adjacent drives. Runs cooler. |
| Woodworking machinery | 2 to 15 HP | BX for saws and planers with small motor sheaves. |
| Printing equipment (legacy) | 1 to 10 HP | B is standard on most legacy printing press drives. |
| Cooling towers | 5 to 25 HP | BX recommended. Humid environment and continuous duty. |
B Section vs. Neighboring Sections
B sits in the middle of the classical range. Here is how it compares to the sections immediately above and below it:
| Feature | A Section | B Section | C Section |
|---|---|---|---|
| Top width | 1/2" | 5/8" | 7/8" |
| Depth | 5/16" | 13/32" | 17/32" |
| HP range | 1/4 to 10 HP | 1 to 25 HP | 15 to 100 HP |
| Min sheave OD | 3.0" | 5.4" | 9.0" |
| Best for | Light duty, under 10 HP | General industrial, 1-25 HP | Heavy duty, 15-100 HP |
| Cogged variant | AX | BX | CX |
If a B-section drive is consistently overloaded and multi-belt configurations are impractical, moving up to C section is the next step. If the drive is over-sized for B and the load is under 10 HP, moving down to A section with smaller sheaves may be more efficient. For compact high-power drives, consider 5V narrow wedge (same top width, higher power per belt, but requires different sheaves). See our V-Belt Selection Guide for more help choosing the right belt type.
Multi-Belt B Section Drives
Many industrial drives use two or more B-section belts running side by side on multi-groove sheaves. This multiplies the drive's load capacity without moving to a larger belt section. Important rules for multi-belt B drives:
- Always replace the full set. Never mix new and worn belts. A new belt is tighter (shorter) than a worn belt, so it carries more than its share of the load and fails early. Replace all belts in the set at the same time.
- Use matched belts. Industrial matched sets are manufactured to tighter length tolerances so all belts in the set are the same length. When ordering multiple B or BX belts for a multi-belt drive, specify "matched set" or order from the same production lot.
- Consider banded. If the drive experiences belt turnover (belts flipping sideways in the groove) or vibration, banded V-belts join multiple belts into a single unit that eliminates these problems.
Frequently Asked Questions
B section V-belts are 5/8" (16 mm) top width and 13/32" (10.5 mm) deep. This is the most common standard industrial V-belt cross section, covering drives from 1 HP to approximately 25 HP. BX 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 3 to get the inside length, which is the part number. Example: OC 103" minus 3 = B100 (wrapped) or BX100 (cogged).
B is a classical wrapped belt with a fabric cover. BX is a cogged (raw edge) belt with molded notches on the underside. Both are 5/8" x 13/32" and fit the same B-groove sheaves. BX runs cooler, flexes easier, handles smaller sheaves (4.0" vs. 5.4" minimum), and lasts 20-30% longer. BX is a direct replacement for B with no changes.
No. Both are 5/8" wide at the top, but they are different cross sections. B is 13/32" deep (classical profile). 5V is 17/32" deep (narrow wedge profile). They use different sheave grooves and are not interchangeable. A 5V belt in a B groove will sit too deep, and a B belt in a 5V groove will sit too shallow. Check the groove depth and angle to determine which you have.
Replace all belts in the set at the same time, even if only one belt has failed. Mixing a new belt with worn belts causes uneven load distribution because the new belt is shorter (tighter) and carries more than its share. This leads to the new belt failing early. Always install a complete matched set.
B68 and B100 are among the most commonly ordered B-section lengths, but the actual most common length depends heavily on the equipment. HVAC air handlers use B50 through B90 most often. Compressors and pumps span B40 through B120. Agricultural equipment can use B100 to B240+. Texas Belting stocks the full range.
Yes. B section is our deepest-stocked V-belt section. We carry both B and BX in the broadest length range from Gates, Continental, Bando, and Diesel Belting. The vast majority of B-section orders ship same day from Houston. Call 888-203-2358 to confirm availability on your specific length.
V-Belt Drive Components
B and BX belts require B-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
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