A gearbox is a mechanical method of transferring energy from one device to another and is used to increase torque while reducing speed. Structural maintenance of gearboxes, gears, shafts bearings and so on built into the body. The reducer is a gear system so the purpose is the same.

We can summarize the objectives as follows;

1. To transmit motion and power between shafts

2. To achieve the various directions of rotation

3. To obtain a large ratios with small volume

4. The system ensures that an independent movement between the rotating elements.