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

The AX is a cogged (notched) V-belt with the same 1/2" x 5/16" cross-section as standard A and 4L belts. The cogged design features notches on the inner surface that increase flexibility, reduce heat buildup, and improve efficiency. AX belts are a direct upgrade for any application currently using A or 4L belts, delivering longer service life and better power transmission without requiring pulley changes.

AX Belt Specifications

Specification Value
Top Width 1/2" (12.7mm)
Height 5/16" (7.9mm)
Belt Angle 40°
Min Pulley Diameter 2.2" (smaller than A/4L due to cogging)
Length Range Same as A belts (inside circumference)
Construction Cogged rubber with polyester cord
Profile Notched/cogged inner surface

Why Choose Cogged? AX Advantages

AX cogged belts outperform smooth A and 4L belts in nearly every measurable way:

  • 2-3% higher efficiency – Cogged construction reduces bending resistance, transmitting more power to the driven equipment.
  • Smaller pulley compatibility – Minimum 2.2" pulley diameter vs. 3.0" for standard A belts, enabling more compact drive designs.
  • Better heat dissipation – The notched inner surface allows airflow between the belt and pulley, reducing operating temperatures.
  • Superior flexibility – Reduced internal bending stress extends belt life, especially in high-flex applications.
  • Ideal for variable-speed drives – Where the belt must constantly adjust to changing pulley diameters, the cogged design flexes without fatigue.

AX vs A vs 4L – Comparison

Feature AX (Cogged) A (Smooth) 4L (Smooth)
Width 1/2" 1/2" 1/2"
Height 5/16" 5/16" 5/16"
Min Pulley 2.2" 3.0" 2.5"
Efficiency Highest Standard Standard
Heat Resistance Better Standard Standard
Measurement Inside length Inside length Outside length
Best For Variable speed, small pulleys General industrial Light/medium duty
Interchangeable? Yes – AX fits the same pulleys as A and 4L belts

Common Applications

  • Variable-speed drives – The primary use case for cogged belts, where constant flexing demands a belt built for it.
  • HVAC systems – Adjustable-speed blower motors benefit from the efficiency gains and reduced heat.
  • Compact machinery – Equipment with small-diameter pulleys that cannot accommodate smooth A/4L belts.
  • High-flex environments – Any drive where the belt wraps tightly around pulleys or idlers.
  • Agricultural equipment – Mowers, tillers, and other outdoor power equipment where efficiency and durability matter.

Understanding AX Part Numbers

AX68 = cogged A-section belt with a 68" inside length. AX belts use the same inside-length measurement convention as standard A belts. To convert from a 4L belt number (which uses outside length), subtract approximately 2" from the 4L number to get the equivalent A/AX inside length. For example, a 4L700 (70" outside) is approximately equivalent to an AX68 (68" inside).

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