고품질의 양금속 구리 부싱; 잘 윤활유 재활용 시스템; 고강도 금속 저항성 금속 금속 금속 금속 금속 Enhancement of wear resistance of rail surace by medium frequency quenching The axle is made of hich quality 45# steel which is enchanced the wear resistance by tempering and high frequency surface heat treatment.