Monday, March 9, 2015

What Are Cogs Anyway?

When communicating with end users of our belt products that are looking for replacement belts, the term “cog” is often used in describing belt features.  Because the term “cog” can be used to refer to many different shapes and features, we do not generally find it to be helpful in identifying appropriate replacements.  Incorrect belt identifications can be easily made unless industry standard and correct terminology is used.  Here are some suggested industry standard terminology to aid in describing belt features:

Longitudinal – Refers to features that lead around belt circumference, or along belt length.

Transverse – Refers to features that lead across belt width, or are perpendicular to belt circumference.  Synchronous belt teeth have a transverse direction.

Notch – V-belts and multi-speed belts are sometimes notched to improve bending flexibility.  Notches can be confused with teeth but the type of hardware used with the belts helps to distinguish.  Notched V-belts run in grooved sheaves and synchronous belt teeth operate in pulleys or sprockets with transverse grooves.

Notched V-Belt
Notched Multi-Speed Belt

Rib – Belt ribs are generally longitudinal in nature, as with Micro-V belts or with multiple strand PowerBand type V-Belts.  Poly Chain and Polyflex type belts have small transverse ribs on their backs.

Longitudinal Ribbed Micro-V Belt
Back Ribs On Poly Chain Belts

Grooves – May be longitudinal if referring to V-belt sheaves, or transverse if referring to synchronous pulleys or sprockets.

Sheave Grooves - Longitudinal
Sprocket Grooves - Transverse

Teeth – Generally refer to transverse features, such as teeth on synchronous belts. Synchronous belt teeth may be described as trapezoidal, curvilinear or gear shaped depending on the belt type.
Trapezoidal Timing Belt Teeth

Curvilinear Synchronous Belt Teeth

These useful belt related terms can be used instead of “cog” when describing belt features.  Feel free to contact us at or on our HelpLine at 303-744-5800.

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