高品質の二金属銅管を使用し 精密に潤滑されたオイルリサイクルシステム 高硬度耐磨性クロアル合金浮きシール&弾性ゴムOリング 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.