1. acceleration and deceleration, it is often said that variable speed gear box.
2. changing the direction of transmission, for example, we use two intermitten power vertical can be passed to another axis of rotation.
3. change the torque. same power condition of gear speed the faster you go, the smaller the torque on the shaft, whereas larger.
4. clutch features: we can separate the two meshing gears, achieve the purpose of the engine separated from the load. brake clutch.
5. the allocation of power. for example, we can use an engine through gear box spindle drive multiple axes, so as to realize the function of an engine driving multiple loads.