有些机械零件的内孔或外圆上加工有不同旋向、一定深度的螺旋槽。它们有的是单螺旋槽,有的是双螺旋槽,而且其旋向与零件的旋转方向相反。零件上的螺旋槽主要有两方面的作用:一是回油,即引导、排泄漏出的机油。例如东方红-75型拖拉机上4125A型柴油机的曲轴后端轴颈上车有右旋、双线螺旋回油槽;丰收180型拖拉机上J285T型柴油机曲轴后端 Some mechanical parts of the inner hole or cylindrical processing with different rotation, a certain depth of the spiral groove. Some of them are single spiral groove, some double helical groove, and its rotation and the rotation of the opposite direction. Spiral groove on the part of the main two aspects: First, back to the oil, that is, guide, drain the oil leakage. Such as Dongfanghong -75 type tractor 4125A diesel engine crankshaft rear axle on the car has a right-hand, double-helical return tank; Harvest 180 tractor J285T diesel engine crankshaft rear end