Causes and Solutions for Brake Failure in Bridge Cranes

In industrial settings, bridge cranes occasionally experience brake failures, which can lead to the dangerous phenomenon of “load slipping.” This happens when the crane operator stops lifting or lowering the load, but the load continues to descend, often beyond the permitted limit of v/100 (where v is the rated lifting speed). This poses serious risks if the load slides all the way to the ground. Another issue occurs when the brake doesn’t release, which restricts the lifting mechanism, preventing the crane from achieving its full lifting capacity.

Causes of Incomplete Braking

Incomplete braking, which allows the load to slip, can stem from several factors:

• Wear and Tear: Frequent use can cause wear on components like pins, pinholes, and brake pads, leading to variations in brake arm position and reduced braking torque.
• Spring Issues: Weak or improperly adjusted main springs reduce braking force, often due to poor material quality or fatigue.
• Misalignment: Radial misalignment of the brake wheel can lead to eccentricity, causing a reduction in braking efficiency.
• Uneven Pad Clearance: Uneven contact between brake pads and the brake wheel reduces torque, often due to installation inaccuracies or loose bolts.
• Obstructed Long-Stroke Brakes: Support material beneath the counterweight can reduce braking torque.

Solutions for Incomplete Braking

To restore reliable braking, the following steps are recommended:

• Replace worn brake components and clear any obstructions.
• Clean the brake wheel and pads with kerosene or gasoline to remove contaminants.
• Re-align or replace misaligned brake wheels.
• Adjust the screws and auxiliary springs for even pad clearance.
• Reinstall brakes with precision to ensure proper alignment and remove any added support under counterweights.

Causes of Brake Locking

When brakes fail to release, common causes include:

• Electromagnet Failure: A disconnected coil stops the magnet, preventing brake release and resulting in a heavy motor sound.
• Bent Brake Rods: Misaligned rods can obstruct movement, causing the brake to remain closed.
• Mechanical Obstructions: Components in the brake mechanism may seize, blocking free movement.

Solutions for Brake Locking

To resolve brake locking issues:

• Replace or reconnect faulty coils.
• Straighten or replace bent rods.
• Identify and eliminate obstructions to ensure smooth operation.

Addressing these common brake issues helps enhance the safety and efficiency of bridge cranes operations, minimizing risks in material handling.