Which safety device must be installed on lattice boom cranes manufactured after February 28, 1992?

The correct choice is that an anti-two block warning device must be installed on lattice boom cranes manufactured after February 28, 1992. The function of this device is critical in preventing a condition known as "two-blocking," which occurs when the hook block makes contact with the boom tip. This can lead to serious accidents, equipment damage, or even fatalities due to the sudden jerking motion that can happen when the two blocks come together.

An anti-two block warning device alerts the operator through visual or audible signals before any damage is done, allowing them to take corrective action. This requirement has been established in safety regulations to enhance the safety protocols surrounding crane operations and ensure that operators have timely information to avoid dangerous situations.

While other safety devices like load limit switches and emergency stop switches are important, they serve different purposes. Load limit switches prevent overload conditions by monitoring the weight being lifted, while emergency stop switches allow immediate shutdown of crane operations in emergencies. The focus on anti-two block devices specifically addresses the unique risks associated with lattice boom crane operation, making it essential for cranes produced after the specified date.