A special requirement for cranes includes:

The requirement for cranes to have devices that prevent the boom from falling back is crucial for ensuring safety during operation. This mechanism is designed to keep the boom in a stable position, reducing the risk of unexpected movements that could lead to accidents or injuries. Such devices are an essential safety feature that helps maintain control and stability while the crane is in use, especially during lifting and lowering operations.

In contrast, the other options compromise safety and operational integrity. Not having load-rating plates would leave operators without critical information about the maximum load the crane can safely handle, significantly increasing the risk of overloading. Allowing modifications without manufacturer approval could lead to unknown consequences, as changes might jeopardize the structural integrity and safe operation of the crane. Lastly, removing safety controls to improve speed undermines the foundational safety principles that govern crane operation, making it far more dangerous for operators and personnel nearby.