Long-term railway service partner
Traction Motor Repairs & Overhaul
Mawdsleys BER has been repairing and overhauling traction motors for over 100 years, working with rail operators, fleet maintenance teams and heritage railway organisations across the UK. We are RISQS approved, hold ISO 9001 and ISO 14001 certification, and operate from a fully equipped workshop in Bristol with a dedicated motor rewind and overhaul facility. Whether you need an emergency traction motor repair to get a unit back into service fast, or a planned fleet overhaul programme delivered to a scheduled timeline, our engineering team has the experience, accreditations and workshop capacity to deliver.
Common Problems With DC Traction Motors
Traction motors are subject to intense, repetitive mechanical and electrical stresses in normal service. The most frequent faults requiring traction motor repairs on DC units include:
- Commutator surface wear caused by overloading, vibration, incorrect brush size or brush wear
- Carbon brush wear leading to a build-up of carbon dust, commutator sparking and damage to the motor’s armature
- Bearing failure, caused by insufficient lubrication, incorrect lubricant, misalignment, excessive vibration, shaft overload and overheating
- Excessive motor vibration leading to carbon brush wear, winding faults, sparking and commutator damage
Our Traction Motor Overhaul Process
Every traction motor that comes into our workshop goes through a detailed, multi-stage overhaul to restore performance, reliability and compliance to the required standard. Our overhaul process covers:
- Initial Inspection & Condition Assessment — We assess the motor for immediate faults, damage and wear. A condition report is provided before work begins, with a clear recommendation for overhaul scope and any unexpected findings.
- Full Disassembly — All components are dismantled, identified and tracked through the overhaul process. Each part is checked for wear, fatigue, distortion or corrosion.
- Deep Clean — The motor is stripped and cleaned to remove carbon dust, contaminants and accumulated debris — essential before accurate assessment and rewinding can take place.
- Armature Rewinding — Where the armature winding has failed or is approaching end of life, a full armature rewind is carried out in our dedicated rewind shop. New winding wire is applied, insulated to the correct class and cured. This is one of the most technically demanding aspects of a traction motor overhaul and a core competency of the Mawdsleys BER workshop
5. Commutator Servicing — The commutator is inspected for surface condition, undercutting depth and concentricity. Where required, the commutator is resurfaced, undercut and polished to restore correct brush contact and eliminate the conditions that cause sparking and carbon buildup.
6. Bearing Replacement — Old bearings are removed and replaced with new, high-quality units specified to the original design requirements. Bearing housings are checked for wear and reconditioned where necessary.
7. Shaft Inspection and Repair — Shafts are checked for straightness, journal wear and keyway condition. Our in-house shaft repair and manufacture capability means worn or damaged shafts are reconditioned rather than requiring a long-lead replacement.
8. Reassembly, Finishing and Testing — The motor is reassembled, cleaned and painted to the required standard. Final testing confirms correct performance to specification — including no-load running, current draw, insulation resistance and vibration measurements — before the unit is returned to service.
Traction Motor Overhaul for Rail Fleets
Emergency traction motor repairs are one part of what we do. For rail operators and fleet maintenance organisations with planned overhaul programmes, Mawdsleys BER provides structured traction motor overhaul services at fleet scale.
Working to your maintenance schedule and critical path, we can handle:
- Life-extension overhauls — comprehensive motor overhauls designed to extend service life rather than replace units, reducing capital costs significantly
- Scheduled fleet overhaul programmes — multiple units overhauled to a defined schedule, with progress reporting and handover documentation at each stage
- Rotable pool management — where turnaround speed is critical, we work with clients to establish an overhauled rotable pool so that a replacement unit is available before the failed unit is withdrawn
- Heritage fleet overhaul — our experience with heritage and vintage traction motor designs, including motors for which no OEM support exists, is demonstrated by our track record in the heritage rail and museum sector
If you are planning a fleet overhaul programme or want to discuss Mawdsleys BER’s capacity and scheduling, contact our engineering team to start the conversation.
Case Studies
RISQS Approved Traction Motor Repair
Mawdsleys BER is RISQS (Railway Industry Supplier Qualification Scheme) approved — the standard qualification scheme for suppliers to Network Rail, train operating companies and the wider UK rail industry.
RISQS approval means we have been independently assessed and verified as meeting the competence, quality and health and safety standards required to work within the rail supply chain. For procurement teams and fleet managers sourcing traction motor repair and overhaul services, RISQS approval is a primary qualification criterion that removes a significant stage of individual supplier assessment.
We also hold:
- ISO 9001 — Quality Management System
- ISO 14001 — Environmental Management System
- AEMT membership — Association of Electrical and Mechanical Trades
- Cyber Essentials Plus — cybersecurity certification
- JOSCAR — defence and aerospace supply chain qualification (relevant for military rail and defence applications)
This is why
1. Speed of service
Reducing your downtime is our main priority. That’s why, from the moment you call to the final report, we move fast. No delays. Just results.
2. High-quality service
With over 100 years experience, we’ve built a reputation on precision, excellence, and constant improvement. You expect the best—we deliver it.
3. One-stop shop
The vast experience of our staff, combined with our state-of-the-art workshop, provide us with flexibility. We do not only repair – we manufacture.
4. ATEX motors specialists
Repairing all types of ATEX motors. We are an AEMT Ex Registered Repairer recognised for our quality systems and professional repair standards.