What does "two-blocking" refer to in crane operation?

In crane operation, "two-blocking" specifically refers to the scenario where the upper and lower blocks of the hoist line come into contact with each other. This typically occurs when the boom is over-extended or excessively raised, causing the load to be hoisted so high that it collides with the crane's structure or other components.

When two-blocking happens, it can result in severe damage to the crane, the load, or even pose safety risks to personnel in the vicinity. Cranes are designed to operate within specified limits, and exceeding these limits by allowing the blocks to make contact can lead to mechanical failure and accidents. The term captures the idea of the load being dangerously crushed between the upper block and the crane, marking it as a critical condition that operators must avoid to ensure safe crane operations.

Understanding this concept is essential for crane operators and riggers to implement safe practices and adhere to operational limits during lifting activities.