1. Absorbing foreign advanced technology of tractor drive axle; 2. Adopting middle-positioned drive axle and swinging central balance pin; 3. The internal structure including central speed reducer ,differential ,terminal double bevel gear reducer ;using whole type axle shell ,which has good rigidity; 4. The central transmission system is compact and occupies little space ,which enhances the tractor 's passing capacity; 5. Adopting back-arranged oil cylinder ,which has compact structure and beautiful appearance; 6. Terminal and king pin streering system adopts composite material sliding bearing structure ,which makes the streering light and flexible; 7. Using separate oil way and full-hydraulic steering; the turning angle can reach 48°;the tractor has small turning radius; 8. Adaptive for 25-32PS narrow-track four-wheel drivetractor.