我厂矿山窄轨铁路９３年投入使用的２０ｍ~３自卸矿车，是鹤壁生产的第一代产品，在长期的使用中，我们发现该矿车轴头存在两个较大的问题：（１）轴承自锁螺母螺纹强度不够，经常松动、滑扣，造成７２２０轴承损坏，每年需更换１００套以上；（２）轴头密封装置不可靠，漏油严 The long-term use of 20m ~ 3 dump truck, which was put into use by our factory’s narrow-gauge railway in 1993, is the first generation product produced by Hebi. In the long-term use, we found two major problems in the shaft of the mine: (1 ) Bearing self-locking nut thread strength is not enough, often loose, sliding buckle, causing damage to the 7220 bearing each year to replace more than 100 sets; (2) shaft seal unreliable, leak tight