Two-blocking alarms sounds during operation: what action should be taken?

• A. Immediately stop and lower load
• B. Continue operation
• C. Increase speed
• D. Notify supervisor only

Answer: (A)

Two-blocking happens when the hook block comes into contact with the upper block or otherwise traps the hoist line between blocks. This can cause rope damage, crane overload, or a sudden load drop. The alarm is there to prevent that dangerous situation. The correct action is to immediately stop hoisting and lower the load to relieve tension and separate the blocks. After that, inspect for the cause (line fouling, faulty limit switches or anti-two-block device, or misadjusted hardware) and follow safety procedures before resuming. Other choices delay or aggravate the risk.