The Challenge
A Johannesburg-based machinery OEM approached Motion Tronic with a Baumüller servo motor and BMaxx drive requiring urgent attention. The motor was due for servicing and was experiencing an encoder-related problem.
With downtime a key concern, the job was treated as a priority repair, with the objective of diagnosing, repairing, testing and returning the equipment as quickly as possible.
Initial cold testing of the BMaxx drive found no faults, allowing Motion Tronic’s technicians to focus their investigation on the servo motor.
Finding the Root Cause
During run testing, the motor produced a group notch error.
Inspection of the resolver assembly revealed that the connecting pin key for the resolver core had come loose and moved out of position. This allowed the resolver core to shift away from its correct position on the stator.
After repositioning the resolver core, the motor was run again. This revealed a second mechanical problem: significant vibration and bearing noise.
The motor was fully stripped for inspection, where our technicians found that both the drive-end (DE) and non-drive-end (NDE) bearings were worn. The DE bearing had also been spinning inside its housing, resulting in wear to the end shield.
The Repair
To restore the servo motor correctly, rather than addressing only the initial resolver fault, Motion Tronic:
- Replaced the DE and NDE bearings.
- Had the damaged DE end shield sleeved and machined.
- Installed a new resolver connecting pin key and securely locked it into position.
- Reassembled and serviced the servo motor.
- Run tested the repaired motor using the customer’s Baumüller BMaxx drive.
The motor was tested at full speed, with no vibration, unusual bearing noise or other issues identified during final in-house testing.
Priority Repair Completed Within One Working Day
Despite the combination of resolver, bearing and end-shield problems discovered during diagnosis, the complete repair and service was completed within one working day.
This priority turnaround helped minimise downtime while avoiding the potential cost and lead time associated with replacement equipment. By addressing both the feedback-related fault and the mechanical wear identified during testing, Motion Tronic was able to return the motor as a repaired, serviced and tested unit.
Key Technical Lessons Learned
This repair demonstrates why accurate fault diagnosis should extend beyond the first reported symptom. What initially presented as an encoder-related problem was traced to a displaced resolver core, but subsequent run testing exposed worn bearings and associated housing damage.
It also highlights the importance of checking the complete servo motor system after correcting a feedback fault. By identifying and repairing both the resolver issue and the underlying mechanical wear, the motor could be returned as a fully serviced and validated unit rather than simply clearing the original error.
For critical industrial equipment, access to in-house diagnostics, mechanical repair expertise and full-speed testing can make the difference between extended downtime and a rapid, successful repair.
The Motion Tronic Difference
At Motion Tronic, our repair process goes beyond addressing the first visible or reported fault. Through systematic diagnostics, mechanical inspection, specialist repair and comprehensive run testing, we work to identify the underlying causes of servo motor problems and verify correct operation before equipment is returned to service.
For this Baumüller servo motor, that approach identified not only the resolver-related problem but also bearing and end-shield wear that could have affected the motor’s reliability if left unresolved.
Need an urgent Baumüller servo motor repair? Motion Tronic provides professional servo motor diagnostics, mechanical repairs, servicing and run testing to help minimise industrial downtime and get critical motion-control equipment back into service.
