This load moment limiter, also known as a black box, uses an MS51 microcomputer as its core control unit, features a modular structure, full key operation, and a liquid crystal display. It offers high precision, stable performance, reliable operation, and easy installation and debugging, along with functions such as digital display, audible and visual alarms, and power-off protection. During crane operation, working conditions often change based on the actual site situation, such as adjusting the lifting angle (range) or boom length. The **rated lifting capacity and working** parameters, as well as the **minimum luffing** range, vary accordingly under different working conditions. Therefore, a device is needed to comprehensively monitor and evaluate these parameters, providing indications of the crane's normal operation, full load, overload, luffing above the upper limit, and luffing below the lower limit, along with corresponding alarms, prompts, and controls to ensure the normal operation of the crane. This product integrates electronic technology, microcomputer technology, and crane machinery technology.