For more than 7 decades, Tianjin JL Railway Transport Equipment Ltd. has manufactured and supplied several hundred millions of springs for all locos, wagons and coach works in railway line. The main products are: Springs used on loco, wagon and coach bogies, large stress spring used on draft gear, valve spring used on diesel engine, spring used on brake, spring used on piston ring, ring spring used on draft gear and so on. For cylindrical helical spring, the diameter of wire is from 0.2mm through 45mm, max. Mean diameter is up to 400mm.
With advanced and completed production, test and inspection equipment for cold and hot coiling springs, our works can manufacture 400, 000 sets hot coiling springs each year. Intermediate frequency induction heater is used from forging ends to coiling procedure for hot coiling spring; Shot blasting machine is used to ensure the blasting strength up to 0.4~0.5A; Coating production line is used to ensure the coating quality of spring. CNC coiling machine imported from Italy is used for cold coiling spring, which has high efficiency and precision. Thanks to the high quality, the fatigue life of valve spring is more than 10, 000.