1: lifting weight limiter function: when lifting load exceeds the rated load, lifting weight limiter can output signals, cut off the lifting control circuit, and can alarm, to prevent overloading the purpose of tower crane. The current national standard "safety code for tower crane tower crane installation shall be specified in the": lifting weight limiter, if has the weight display device, the numerical error can not be larger than the actual value of 5%, when the weight is greater than the maximum rated the appropriate gear value and less than rated value 110% of the time, we should cut off the power supply and lifting mechanism of the upward direction, but can be used for the descent direction of movement.

2: from the structure and working principle of the weight limiter: at present the most commonly used form of the structure of lifting weight limiter for force measuring ring, which is composed of a force measuring ring, a guide pulley and a limit switch etc.. Its features are compact volume, good performance and convenient adjustment. All kinds of tower crane widely used all kinds of this structure. A crane mechanism fixed on the support force of the ring, the other end is fixed on the guide pulley. Working principle: the tower crane load, by the resultant force of pulley wire rope, the force is transmitted to the force measuring ring ring dynamometer, the deformation and load into a certain proportion. According to the size of the lifting load, pulley sent by force are also different. Force measuring ring shell with the force deformation, ring shell is fixedly connected with the force measuring metal lath force within the ring, and with the casing deformation and extended, this time according to the load to the adjusting bolt is fixed on the metal strip and a limit switch distance, when more than the rated capacity to limit switch action load, which can cut off the power supply of the rising mechanism, achieve the purpose of weight overload limit.