Belt & Gear Mesh Frequencies

To read the spectrum of belt and gear drives you first need these frequencies. Enter the values; the frequency table and a marked spectrum appear instantly.

HzCPMrpm

Driver 1X———

Driven speed———

Belt pass frequency———

Gear mesh frequency (GMF)———

Gear speed———

Hunting tooth frequency———

Belt speed: —

Expected spectrum components

These tools are intended for preliminary assessment and training. Decisions on critical equipment should be based on on-site measurement and expert evaluation.

How to use

For the belt drive, enter motor speed, both pulley diameters and belt length.
For the gear stage, enter pinion speed and both tooth counts.
Look for these frequencies and the ±1X sidebands around GMF in your spectrum.

Theory & formulas

Belt pass frequency f_b = π · D₁ · n₁ / (60 · L). Belt faults usually appear at f_b, 2·f_b and 3·f_b, below shaft speed.

Gear mesh frequency GMF = Z₁ · n₁ / 60. A faulty gear produces sidebands around GMF spaced at its own shaft speed.

Hunting tooth frequency f_HT = GMF · N_a / (Z₁ · Z₂), where N_a is the greatest common divisor of the tooth counts.

Frequently asked questions

Why do gear sidebands matter?

The sideband spacing shows which shaft is involved: sidebands at pinion speed point to the pinion, at gear speed to the gear. Rising sideband amplitudes can indicate tooth wear, eccentricity or a broken tooth.