Gear Pumps

Gear pumps are commonly used for pumping lube oil, and they almost always have a strong vibration component at the tooth mesh frequency, which is the number of teeth on the gear times the RPM. This component will be highly dependent on the output pressure of the pump. If the tooth mesh frequency changes significantly, such as the sudden appearance of harmonics or sidebands in the vibration spectrum, it could indicate a cracked or otherwise damaged tooth.

Typical Gear Pump Spectrum