YHG-1200 mobile flash-butt welding machine provides the good environment for the field steel track welding and reduces the labor intensity of field operation, so that the field steel track welding quality meets or gets close to the level of plant welding, and can meet the seamless requirements of high-speed railway or passenger railway etc. The application of LR1200 welder meets the on-railway welding, off-railway welding and lock welding etc.; the rail pulling and aligning system is equipped on the left and right sides of complete vehicle to pull and align the steel track during the welding; the action system is hydraulically driven to the max. self-propelled speed of 100km/h; the frame is designed as the upper chord beam, provided with stable dynamic performance, reaching the max. coupling speed of120km/h; brake system adopts the reliable brake unit. It is the ideal welding machine for seamless tracks.