Ultrasonic Inspection: Gearboxes

Ultrasonic Testing

Teeth deformation and wear depend upon the type of sliding contact associated with the various types of gear sets. The operation of different types of gears emits a wide spectrum of airborne and structure-borne ultrasonic vibrations. Ultrasonic vibrations are the evidences of the operational conditions of the gears, as well as the rest of the transmission. The spectrum of ultrasound vibrations depends upon many design and operational features of the gear drive, namely:

• Type of power drive (electrical, hydraulic or pneumatic, internal-combustion engine, any kind of turbine, etc.
• Linkage and alignment of drive unit and gearbox.
• Design of gearbox and type of gear set itself.
• Ultrasound emitting from adjacent industrial equipment.

The type of gear mesh and its operating regime under dynamic loading (vibration of tooth gears in backlashes, deficiency of lubricating of gear sets and bearings, etc.) predetermine the type of possible damage. Therefore, consequent ultrasonic signals are evidence of the types of faults and malfunctions.

When testing the gearbox, it is necessary to be familiar with the operating conditions and normal sounds produced. Using the UL101 in contact mode, listen to several points near specific components. The UL101 can be adjusted to distinguish the high-pitched sound of the input shaft. The output shaft may sound low and monotonous or low and have a natural clicking. It depends upon the type of gears and the load.

<< Prev: Types of Gearboxes || Next: Case Studies>>