一台上海—50型拖拉机空运转时无任何故障征兆而突然熄火,再也无法启动。发动机抱轴了?拆下油底壳偏差,发现发动机各缸连杆均有正常的轴向间隙,且飞轮可以反转一定角度,踏下离合器踏板,发动机可以启动,发动机发生故障的可能性被排除。拆卸检查变速箱,发现动力输出轴从动齿轮与常啮合齿轮间嵌入两块异物,但没发现变速箱有掉 A Shanghai -50 tractor air run without any symptoms of failure and suddenly turn off, can no longer start. The engine is holding the axle Remove the deviation of the oil sump and found that the engine cylinder connecting rod has a normal axial clearance, and the flywheel can be reversed a certain angle, depressing the clutch pedal, the engine can start, the possibility of engine failure exclude. Disassembly inspection gearbox and found that the output shaft driven gear and constant meshing gear embedded between two foreign bodies, but did not find gearbox out