Applicable Systems
CM

Symptoms

The hoist brake fails to hold the load when the motor stops. The load drifts downward, indicating brake engagement failure.

Possible Causes

  • Brake disc or shoe worn beyond the minimum thickness
  • Brake actuator (pneumatic, hydraulic, or electromagnetic) not developing sufficient force
  • Brake spring fatigued, reducing the clamping force
  • Oil or grease contamination on the brake friction surfaces

Troubleshooting Steps

  1. Step 1: Measure the brake disc or shoe thickness and compare to the minimum specification
    Replace if below the minimum thickness stamped on the component
  2. Step 2: Check the brake actuator: air pressure, hydraulic pressure, or coil voltage
    Repair or replace if the actuator does not achieve the rated force
  3. Step 3: Inspect the brake friction surfaces for oil or grease contamination
    Clean with solvent; replace the friction material if saturated
  4. Step 4: Measure the brake spring free length and compare to the specification
    Replace springs that have taken a set (shortened)

How to Reset

Reset: After brake repair or replacement, perform a load test with a test weight to verify the brake holds 125% of rated load before returning to service.

Common Replacement Parts

  • Brake disc: OEM-specified, match to hoist model (Replace at minimum thickness)
  • Brake friction material: Asbestos-free, OEM-specified (Replace in matched sets)
  • Brake spring: Die-spring type, match to OEM spec (Replace in sets)

Frequently Asked Questions

  • Q: How often should crane brakes be inspected?

    Daily before operation: visual check. Monthly: functional test. Annually: disassembly, measurement, and load test.

  • Q: What is the brake holding test?

    Lift a test load, stop the hoist, and verify the load does not drift. Then test with 125% of rated load for new installations or after major repairs.

  • Q: What causes brake failure?

    Wear, contamination, spring fatigue, actuator failure, and thermal damage from excessive cycling. Regular inspection and maintenance prevent most failures.

Related Columbus McKinnon Crane Fault Codes

Source: OEM Operation Manual

Category: Crane