RC-A5-I load moment indicator is applicable to all types of level-jib and flat-top tower cranes.The system adopts 51 single chip and 5 inch LCD,it indicates real-time working state of tower crane and record,once overload,it will cut off circuit and prevent dangerous operation,ensure crane safety operation. It provides the operator with actual and correct information on working states of tower crane on as follows through LCD:actual load,rated load,hook height,hook amplitude,slewing angel and wind speed etc.If the load reaches 50% or 80% specified moment,it will pre-alarm.If it reaches 105%,it will alarm and prevent the trolley automatically from moving outward and the hook from lifting upward.