When a traction motor starts making an unusual noise, it’s tempting to assume the worst — a full rewind or replacement. This case study shows how a structured traction motor overhaul process turned what looked like a serious mechanical fault into a fast, low-cost repair.
Our engineers regularly carry out traction motor repairs and overhauls for AC and DC motors across the rail sector, from single emergency call-outs to planned fleet overhaul programmes. Here’s how we handled one recent case — from initial diagnosis through to the motor being back in service inside 48 hours.
Our traction motor overhaul & repair process
- Initial run-up test — the motor was run under controlled conditions to reproduce and isolate the fault noise.
- Fault diagnosis — the noise was traced to a worn drive-end bearing.
- Full disassembly — the motor was stripped down and cleaned for thorough inspection.
- Winding test — insulation resistance testing confirmed the windings were sound, so no rewind was needed.
- Bearing replacement — sensor-fitted replacement bearings were sourced and installed during reassembly.
- Re-test & sign-off — the motor was re-run and confirmed fault-free before release.
The result
- Turnaround: 48 hours from receipt to return
- Labour cost: just 3 hours — accurate diagnosis meant no unnecessary work
- No rewind required — a targeted repair, not a full overhaul rebuild
- Motor returned to full working condition, ahead of schedule
Also investigated: DC traction motor fault
Alongside the AC motor above, we also carried out traction motor repairs on a Schabmuller 1.7kW 24V DC unit. Though still running, its performance had been gradually declining. Inspection found flat spots and burning on the commutator surface. The motor was restored to as-new condition through a commutator skim and undercut, new bearings and brushes — bringing performance back to its original specification.
When does a motor need a full overhaul vs. a targeted repair?
Not every fault means a full traction motor overhaul is required. As this case shows, correct diagnosis is what determines the right level of intervention:
- Targeted repair — appropriate when the fault is isolated (e.g. a single bearing or brush) and the windings and core components test sound.
- Full overhaul — appropriate when multiple components show wear, when a motor has had no proactive maintenance for an extended period, or ahead of a planned fleet maintenance cycle.
Early investigation of noise, vibration, or performance drop-off is what keeps a repair in the “targeted” category — and keeps the bill down.
Why this matters for your motors
Whether it’s a traction motor on a train, or an industrial AC motor on a production line, the principle is the same: early investigation of noise, vibration or performance drop-off usually means a faster, cheaper repair — and avoids the motor failing completely.
If you’re dealing with similar symptoms, our team can run the same diagnostic process on your motor.
Talk to the experts
Find out more about our expertise within the railway sector here.
Call 01179552481 or email enquiries@mawdsleysber.com and get your quote today!
