What is the purpose of sheaves in tilt-up lifting?

• A. Used to connect the temporary braces to the slab
• B. Used to handle 2 lift points with one connection to the spreader bar, maintaining an equal load on both inserts
• C. Used to provide an anchor to the foundation
• D. Used to lift loads from a crane

Answer: (B)

The key idea is balancing the lift forces across two lift inserts using a spreader bar with pulleys. Sheaves on the spreader bar guide the lifting line so it feeds down to both inserts from a single crane connection. This setup lets the crane pull on the two points more evenly, helping keep the panel level and preventing one insert from taking more load than the other. In tilt-up lifts, equal load distribution on the lift inserts is crucial for a safe, stable lift, and the sheaves make that possible with a single lift point connected to the spreader bar.