How many wraps can remain on the drum at its lowest point if equipped with a lower limit device?

The correct answer indicates that one wrap can remain on the drum at its lowest point if the crane is equipped with a lower limit device. This is crucial for ensuring safe operation and preventing the hoisting mechanism from being overly stressed or damaged.

A lower limit device is designed to stop the motion of the hoist before the load or hoist mechanism reaches an untenable position. If there were no wraps remaining on the drum, there would be a risk of the rope becoming completely unwound, which could lead to a severe safety hazard or equipment failure. Conversely, allowing two or more wraps could create additional slack, diminish control, and complicate the operation when lowering the load.

Thus, allowing a single wrap on the drum strikes a balance, ensuring that the load is secure while minimizing the risk of malfunction or operational issues. This practice follows safety protocols and guidelines to maintain effective and secure use of overhead cranes.