Scenario

A local quarry reached out to our team with a request for an overhaul on one of their motors as part of planned maintenance on their site. With a spare motor installed to maintain operations, they sent the existing motor to us for a routine check and refurbishment. We collected it directly from the site and brought it into our workshop, preparing to dismantle and inspect the unit for any issues before beginning the overhaul.

Inspection & DIAGNOSIS

Our initial inspection revealed several critical issues:

• a broken thermistor lead in the terminal box – likely damaged when supply leads were removed
• brushes stuck within their boxes due to heavy powder build-up – which would have led to arcing or sparking
• signs of poor contact on the brush gear leads, with melting around the lug edges due to dust accumulation causing resistance.

“The stator was packed with quarry dust, releasing dense clouds of powder for hours during cleaning—a clear indication of the impact on both performance and safety. After an extensive airline cleaning, we applied steam cleaning and stove drying to the stator, rotor, and brush gear assembly to ensure thorough decontamination of all internal surfaces. Once clean, both the stator and rotor passed the Baker Test, confirming insulation integrity. With diagnostics complete, repairs could begin.

REPAIR & OVERHAUL

The first phase of repairs involved:

• Skimming the slip rings
• Re-leading the broken thermistor connection and repositioning it in the terminal box to avoid future damage.
• Re-leading brush gear to address poor connections and prevent electrical issues.
• Re-sealing the stator and terminal box entry points to limit future dust ingress.

Finally, we applied insulation paint to the stator and rotor windings, restoring the protective layers that had worn down over time and enhancing the motor’s durability under the harsh conditions of its application.

In addition to these specific repairs, we also replaced standard wear components, including new bearings and brushes, to ensure reliable performance once the motor was back in operation.

RESOLUTION

With all repairs completed, we carefully reassembled the motor, aligning and securing each component to prevent any mechanical or electrical faults. We then conducted a series of electrical and operational tests to confirm that the motor was functioning correctly and that the issues identified during troubleshooting had been effectively resolved.

As a final step, we painted the motor’s exterior to protect it from the harsh environmental conditions at the quarry. With the motor fully restored and tested, we returned it to the client along with a detailed report of the work completed, including test results and recommended maintenance practices to help extend its lifespan.

Our thorough approach ensured the motor was ready to withstand demanding conditions, restoring it to optimal function and reliability for future use at the quarry.