What phenomenon is common with an odd number of parts of line reeving?

• A. Block twist
• B. Sway
• C. Swing arrest
• D. Line wear

Answer: (A)

When a block is reeved with an odd number of parts of line, the pulling forces around the block aren’t balanced on both sides. This creates a turning moment that tends to twist the block itself as the line runs over the sheaves. In practical terms, the hook block will begin to rotate or twist relative to the crane as it is lifted or lowered, because there isn’t a symmetric counteracting pull to keep the block orientation fixed. That rotation is the block twist.

If the line parts were even, the forces can balance more neatly and the block tends to stay oriented as it moves. Sway and swing are broader load motions caused by crane movement, wind, or stopping/starting of the crane, not specifically tied to whether the line parts are odd or even. Line wear is about friction and abrasion over time, not about the parity of line parts. So the twist of the block due to an odd number of line parts is the phenomenon described.