A tower crane with a load capacity of 50 tons will pick up 50 tons of goods, move them to the designated position and put them back down. Then, a steel plate of about 2 square meters was added on it. At this time, the lifting weight limiter installed in the cab began to give an audible and visual alarm, and controlled the crane not to continue the forced lifting, but only to return and put down the goods. On the construction site, the various crane safety protection devices developed and produced by Yichang Weite Electronics Co., Ltd. have won the unanimous praise of the owner and Liaoning safety science and Technology Research Institute, which came to the site for testing, for their excellent performance and stable state.