BX Cogged V-Belt Guide - Specifications, Sizing & Comparison

The BX is a cogged (notched) V-belt with the same 21/32" x 13/32" cross-section as standard B belts. The cogged design improves flexibility, reduces heat, and increases power transmission efficiency. BX belts handle heavier loads than AX belts and are the go-to upgrade for any B-section drive that demands better performance.

BX Belt Specifications

Specification Value
Top Width 21/32" (16.7mm)
Height 13/32" (10.3mm)
Belt Angle 40°
Min Pulley Diameter 3.4" (smaller than B due to cogging)
Length Range Same as B belts (inside circumference)
Construction Cogged rubber with polyester cord
Profile Notched/cogged inner surface

Why Choose Cogged? BX Advantages

BX cogged belts deliver measurable improvements over smooth B and 5L belts:

  • 2-3% higher efficiency – Less bending resistance means more power reaches the driven equipment, reducing energy costs on heavy-duty drives.
  • Smaller pulley compatibility – Minimum 3.4" pulley diameter vs. 4.6" for standard B belts, allowing more compact drive configurations.
  • Better heat dissipation – Notches on the inner surface promote airflow between the belt and pulley, keeping operating temperatures lower.
  • Superior flexibility – Reduced internal stress at bend points extends belt life significantly in high-flex applications.
  • Ideal for variable-speed drives – The B-section handles higher horsepower than A-section, and the cogged design adds the flexibility needed for constantly changing pulley ratios.

BX vs B vs 5L – Comparison

Feature BX (Cogged) B (Smooth) 5L (Smooth)
Width 21/32" 21/32" 21/32"
Height 13/32" 13/32" 3/8"
Min Pulley 3.4" 4.6" 3.5"
Efficiency Highest Standard Standard
Heat Resistance Better Standard Standard
Measurement Inside length Inside length Outside length
Best For Variable speed, small pulleys Heavy industrial Medium duty FHP
Interchangeable? Yes – BX fits the same pulleys as standard B belts

Common Applications

  • Heavy industrial variable-speed drives – Conveyors, pumps, and compressors that require adjustable speed with high torque.
  • Compact heavy machinery – Equipment with smaller pulleys that still needs the load capacity of a B-section belt.
  • HVAC systems – Large commercial air handlers and blowers where efficiency directly impacts energy costs.
  • Agricultural equipment – Combines, balers, and other farm machinery with demanding drive requirements.
  • Industrial fans and blowers – High-speed applications where heat buildup shortens the life of smooth belts.

Understanding BX Part Numbers

BX62 = cogged B-section belt with a 62" inside length. BX belts use the same inside-length measurement convention as standard B belts. The number after "BX" is the inside circumference in inches. To convert from a 5L belt number (which uses outside length), subtract approximately 3" from the 5L number to get the approximate B/BX inside length. For example, a 5L650 (65" outside) is approximately equivalent to a BX62 (62" inside).

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