MDI Case Study: Gearbox Damage

This case study was provided by our educational collaborator Machinery Diagnostics Institute (MDI)

Download the printer-friendly Gearbox Damage Case Study

Introduction
Gearboxes play a critical role in industrial machinery, but they are also prone to wear, misalignment, and other defects. As a result, regular condition monitoring is essential to determine early signs of wear and tear and ensure operational uptime.

Analysis
MDI was commissioned to perform a typical route-based data collection and noticed some warning signs on the gearbox.

Products Used
MDI utilized the following CTC condition monitoring hardware for this analysis:

A render of a CTC AC216-1A side exit vibration monitoring sensor on an MH214-3A mounting magnet.

CTC’s AC216, a popular magnet-mount accelerometer specially engineered for route-based measurements and CTC’s MH214-3A, a multipurpose two-rail mounting magnet.

A render of a CTC cable assembly with C555 connector, CB104 coiled cable, safety feature, and K2C connector.

CTC’s CB104-C555-006-K2C-SF, an Emerson/CSI compatible cable and connector assembly.

Findings

The motor shows acceptable but high (moderate) vibration levels according to the ISO Standards 2081-3 as per machine class and type.
The motor shows elevated vibration at the running speed component 1X (13.56 Hz) with an amplitude of (6.4 mm/s rms) indicative of a few causes such as structure looseness and excessive clearance.
The gearbox also shows elevated vibration at the running (input) speed, in addition to impacts on the TWF which could be an indication of internal damage in the gearbox.

Data Collected by MDI
A graph of the motor vibration spectrum on the gearbox.

A graph showing the sharp impacts in the gearbox TWF.

Conclusion
As a result, MDI requested a borescope inspection to confirm the condition of the gearbox. Utilizing a borescope to validate some early warning signs allows technicians to identify defects, wear, or damage in inaccessible spaces without disassembling machinery or structures.

Following the borescope examination, damage consistent with the vibration data was validated as depicted in the photo below:

A photo showing the damage to the gearbox is consistent with the vibration data collected.

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About MDI
Machinery Diagnostics Institute based in Queensland, Australia, is an official educational partner of CTC. They are recognized globally as some of the most highly-regarded trainers and educators in the vibration analysis industry. MDI offers in-person and virtual technical trainings on topics including vibration analysis, thermal imaging, machinery lubrication, ultrasound testing, turbo machinery, machine balancing, shaft alignment, and asset reliability. The MDI team is proud to partner with other industry leaders including Mobius Institute, ICML, and Infraspection Institute.

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