What should I do if the emergency brake of the single-beam bridge crane fails

When the single-beam bridge crane experiences emergency brake failure, the following step-by-step emergency measures should be taken immediately, combining mechanical and electrical troubleshooting to ensure the safety of personnel and equipment:

1. Emergency response stage (0-1 minute)

Cut off the power supply

Quickly press the emergency stop button to cut off the power supply to the crane and prevent the fault from escalating. For bridge cranes with a general rated lifting capacity of 5-10 tons, the emergency stop response time should be controlled within 0.1-0.3 seconds.

Attempt to restore the braking function

If conditions permit, use the control handle to jog the operation and make the brake act repeatedly. About 15%-20% of brake malfunctions can be temporarily restored by this method.

Raise the alarm and evacuate personnel

Immediately sound a clear and loud alarm through a siren or whistle to ensure that personnel within a radius of 50 meters evacuate from the dangerous area.

II. Fault diagnosis and elimination stage (1-5 minutes)

Mechanical system inspection

Brake clearance: Check the clearance between the brake wheel and the brake shoe lining. The normal clearance should be 0.5-1.0 mm. If the clearance is too large, it needs to be adjusted to the standard value.

Brake wheel surface: Inspect the brake wheel for any signs of oil stains, wear, or burns. If the surface roughness exceeds Ra3.2-Ra6.3, the brake wheel needs to be cleaned or replaced.

Main spring elasticity: Use a professional spring tester to measure the elasticity coefficient of the main spring. If the elasticity is insufficient or the spring is fatigued and broken, it needs to be replaced.

Lever joint: Check whether the lever joint is stuck (due to rust or foreign matter), remove any obstructions, and apply lubricant.

Electrical system inspection

Brake electromagnet: Check whether the electromagnet coil is open-circuited or lacks suction force. If the electromagnet does not engage, replace the coil or adjust the wiring.

Wiring and Contactor: Inspect the wiring and contactors related to braking in the electrical control system, checking for any looseness, short circuits, or poor contact. Approximately 30% of brake malfunctions are caused by issues with the electrical wiring.

Limit switch: Confirm whether the up/down limit switch operates reliably. If it fails, it needs to be adjusted or replaced.

III. Heavy object handling stage (5-10 minutes)

Lower the heavy object slowly

If the crane is lifting a heavy object, it is necessary to lower the object to a safe location as slowly as possible. For cranes with a lifting speed of 0.5-1.5 meters per minute, the lowering process should be operated smoothly to avoid sudden acceleration that could lead to loss of control.

Avoid misoperation

Prevent accidentally placing the control handle in gear 1 (mistakenly thinking it is returning to zero), which can cause a false sense of brake failure. When operating, gradually shift gears to avoid triggering the overcurrent relay too quickly.