Brake feedback faults — the first family
Gearless drives use a fail-safe electromagnetic brake that grips the traction sheave when the motor stops. Two microswitches confirm the brake has released before the motor tries to move, and re-engaged before the controller drops power. Fault codes in the brake family typically indicate:
- One brake shoe releasing but the other sticking.
- A microswitch drifting so ‘released’ isn't reported cleanly.
- A brake coil warming above spec and reducing pull force.
Any brake fault is safety-critical — the lift will not run until it clears — and requires a competent engineer with the specific model's service kit. Do not attempt any reset beyond a single controller cycle.
Encoder faults — the second family
The rotary encoder on the motor shaft is the sole position feedback on a gearless drive. Encoder faults:
- Missed pulse — a brief loss of signal, usually a loose connector. Symptom: intermittent overspeed trips on start.
- Direction disagreement — the encoder reports motion in a direction the controller didn't command. Symptom: immediate stop with an under-voltage or brake trip.
- Total loss — encoder failed. Symptom: lift will not start; the drive can't confirm the motor is stationary before releasing the brake.
Over-current trips
Gearless drives protect the motor with a current-monitoring circuit that trips if load exceeds a rolling limit. Genuine over-currents mean:
- Mechanical drag — a partly-released brake, a rope out of the sheave groove, a car hitting a guide-rail obstruction.
- Motor winding damage — insulation failure in one phase pulling excess current.
- Rope-slip on the sheave — a wet-lubricated or contaminated sheave losing traction.
All three are engineer-diagnostic and often require the OEM's software to read the drive log properly.
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Describe your symptom →Reading the pattern, not just the code
Safe to check yourself
A single fault is a fault. Three or four faults in a week is a pattern, and the pattern says more than any one code:
- Brake fault + over-current on the same trip = brake dragging.
- Encoder fault + over-current at a specific landing = rope groove wear at that landing's stopping point.
- Multiple brake faults over cold mornings = brake coil resistance drifting with temperature — coil replacement due.
The modernisation decision
UK gearless commercial drives typically give 15–20 years of first-life service before recurrent faults make continued repair uneconomic. Warning signs the drive is at end of first life:
- Fault frequency has doubled year-on-year for two years.
- OEM spares availability is falling (a real issue on drives 10+ years old — some parts are no longer stocked in the UK).
- Cost of the annual repair total exceeds 15–20% of a full modernisation quote.
A modernisation is not a full replacement — the shaft, doors and cabinet often stay — but replaces the drive, controller and safety chain to current spec. UK LOLER inspection results across the last five years of the lift's life inform the timing.
Escalation and duty-holder responsibility
Stop — call an engineer
A gearless-drive fault on a UK commercial lift is not something building staff should attempt to reset via the machine-room controller. Duty-holder responsibilities under LOLER:
- Ensure the lift is isolated by a competent person if it has any brake or safety-chain fault indication.
- Log the fault against the lift's history file — separate from the LOLER report.
- Do not authorise return-to-service until the responsible engineer has confirmed in writing that the fault is diagnosed and either resolved or safely contained.
Frequently asked questions
- Can we run the lift on the emergency-lower system while the drive is faulted?
- No. The emergency-lower is a one-shot evacuation system, not a workaround for continued operation. Running the lift with a known drive fault is a LOLER offence and voids all warranties.
- How long can we expect between drive services?
- UK commercial lifts on standard PPM contracts see a drive-specific service every 12 months, in addition to the two 6-monthly thorough examinations. Heavy-use lifts (hospitals, retail) may double that frequency.
- Is a rising fault frequency always a sign of imminent failure?
- Not always — it can be a controller firmware issue that a manufacturer update resolves. Ask whether recent OEM bulletins address the observed fault pattern before committing to a modernisation quote.
- Are OEM-only spares always the right choice?
- For safety-critical components (brake, ropes, safety gear, controller boards): yes, always OEM. For non-safety wear items (cabin lights, floor buttons): third-party is acceptable if certified. UK LOLER competent-engineer sign-off is the arbiter.
- What information does the engineer need before attending a drive fault?
- Fault code + timestamp; whether the lift is stopped in the shaft or at a landing; any recent building works nearby; the last drive-specific service date; number of drive faults in the last 30 days. Sending this ahead of the visit routinely saves 30–60 minutes on site.