Case Study: Brake Rewind, Brake Shoes, and MC Contactor Service
Background:
Omni Lifts was tasked with a repair involving a lift that had been in service since the 1960s. The lift had undergone partial upgrades over the years, but required brake repairs and MC Contactor replacement.
Scope of Work:
Attending the site and ensuring lift safety.
Prop or buffer counterweight for secure operation.
Removing and rewinding the lift brake coil.
Replacing the lining of brake shoes due to uneven wear.
Supplying and fitting a new MC contactor.
Returning to the site to refit and set up the brake, including conducting an A22 safety test.
Work Carried Out
Attended site and made lift safe.
Removed lift main brake coil for rewind in the workshop.
Removed brake shoes for reline due to uneven wear.
Ascertained information for MC contactor replacement.
Returned to site with new brake linings, re wound coil and new MC contactor.
Fitted brake to machine, found that brake was not setup to correct height and centre line of drum.
Fitted shims to brake assembly to correct height.
Setup brake spring tension and checked for correct fitting as per LEIA technical bulletin.
Feeler gauges used to check clearances
Wired and terminated brake coil.
Setup solenoid to minimal operating clearance and to reduce back EMF.
Replaced MC contactor with new.
Carried out A22 SAFed brake testing with 125% load.
SAFed testing
Upon testing found issue with lift safety gear. Safety gear springs have become loose allowing the gear to move freely when lift stops/starts. This in turn breaks the gear switch and stops the lift from operating. Setup safety gear spring tensions and carried out testing and operated gear by hand. All operational.
Lift tested to each floor and returned to service.
lift shaft switch gear still uses the original floor selector on the machine room tape. This causes unreliable floor levelling and poses a trip hazard to the user.
Outcome:
Successful overhaul of the braking system, including rewinding the brake coil and replacing the brake linings.
Replacement of the MC contractor
The lift was rigorously tested with a 125% load to ensure compliance with A22 safety standards and returned to service.
Recommendations:
A full evaluation and recommendation for modernising the lift were provided to the client, highlighting the need for updating the shaft switch gear and floor selector for improved safety and reliability.
Omni Lifts strongly recommends a comprehensive modernisation of the lift system. The current state, with its outdated controller and original floor selector, presents reliability issues. Modernisation would not only enhance the lift's performance but also ensure compliance with current safety standards.
Nov
2023
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