Looking after a brake motor on a hoist or conveyor

Electromagnetic brake motors hold loads on hoists, cranes, conveyors and lifts when power is switched off. They are reliable, but the brake is a wearing part, and a neglected brake is a safety risk. Here is the maintenance we suggest.

Check the air gap every three months on busy machines. The brake works by a spring pushing a friction disc against a plate when power is off; an electromagnet pulls it free when power is on. As the lining wears, the gap between the armature and the magnet body grows. Measure it with feeler gauges at three points around the disc. If it is beyond the limit on the motor’s plate, usually 0.6 to 0.8 mm for our smaller sizes, adjust it back to the setting, typically 0.3 to 0.4 mm. Inspect the friction lining at the same time. Replace the disc when it reaches the minimum thickness, or if it is glazed, cracked or oily. Oil on a brake lining usually comes from a leaking gearbox seal, which needs fixing at the same time.

Listen and watch. A brake that releases slowly, chatters or smells hot often has a failing rectifier, the small unit that turns AC into DC for the brake coil, which costs far less than a new brake. A load that creeps down after stopping needs attention at once; stop using the hoist until it is checked.

Finally, test the manual release lever and put it back in its locked position. Keep a log of every check. Our service team can train your maintenance staff on a site visit.