Parts are the basic elements of a machine and can be broadly divided into two categories: one is the parts that can be used in various machines (such as gears, shafts, etc.), called general parts; the other is The parts (such as gun bolts, propellers, etc.) that are only used in the type of machine are called special parts; in addition, the part assembly composed of some cooperative parts is called parts or components (such as couplings, reducers, etc.). Wait)
