一台东方红-75型拖拉机,一年内更换了四副活塞、活塞环、气缸套,工作最长的一副只有半个月,最短的不到一星期。拆检发现,活塞环严重磨损;在缸套的顺机体前方,被活塞销卡簧拉出两道深槽;活塞上的卡簧槽已磨损,无法安装卡簧,造成活塞报废;连杆弯曲度超限。经过了解得知,该车曾用于 A Dongfanghong -75 tractor, within a year replaced four pistons, piston rings, cylinder liner, the longest working pair of only half a month, the shortest less than a week. Disassembly found that the piston ring serious wear and tear in front of the cylinder along the body, the piston pin card spring pull out two deep groove; piston spring groove has worn, can not install the spring, resulting in piston scrapped; connecting rod bending Exceeded. After understanding that the car had been used