What is the function of sheaves and how do worn sheaves affect lifting operations?

• A. Sheaves guide the rope and reduce friction; worn or misaligned sheaves cause rope wear, reduced efficiency, increased drum wear, and potential rope damage or failure.
• B. Sheaves are decorative; wear has no effect.
• C. Sheaves provide counterweight balance; wear harms balance.
• D. Sheaves store the rope when not in use; wear reduces storage capacity.

Answer: (A)

Sheaves act as pulleys that guide the wire rope and change its direction while keeping friction low so the rope can move smoothly. Their grooves support the rope and help it bend safely without sharp bends that would wear it out.

When a sheave is worn or misaligned, the rope doesn’t sit properly in the groove, causing uneven contact and higher friction. That speeds up rope wear and generates more heat, which can lead to rope damage or failure. It also increases wear on the drum where the rope winds, and overall lifting efficiency drops because more energy is lost to friction. Keeping sheaves in good condition and correctly aligned helps preserve rope life, maintain smooth operation, and improve safety.