This invention is an automatically-controlled device which can be used to discriminate the stalling state of the wheels of a train.It is composed of three parts-a receiving treadle, an amplifying printed circuit board and relays. The receiving treadle is composed of a base, permanent magnets, coils, epoxy resin fillings, outer case and lead-out wires. The amplifying printed circuit board is composed of an oscillaing stage, a frequency selective amplifying stage and a power amplifying stage, transformer couplings are used in interstage couplings. This invention can check the state of the stalling of a train reliably. |