What is the basic working principle of a gearbox? How is energy converted in it

A reducer is a power transmission mechanism that uses a gear speed converter to reduce the number of revolutions of an electric motor (motor) to the desired number of revolutions and obtain a larger torque. Here is a detailed introduction to its working principle and energy conversion process:
Basic working principle

Gear transmission principle: The most common structure of a reducer is based on gear transmission. It is mainly composed of an input shaft, an output shaft, and a series of meshing gears. When a power source (such as a motor) drives the input shaft to rotate, the gears on the input shaft will drive the next gear that meshes with it to rotate. Due to the different number of teeth on different gears, according to the basic law of gear transmission, that is, the number of teeth is inversely proportional to the speed, the speed can be changed. For example, if there are fewer teeth on the input shaft and more teeth on the output shaft that meshes with it, the speed of the output shaft will be lower than that of the input shaft, thereby achieving the purpose of deceleration.

Multi stage transmission achieves large reduction ratio: In order to obtain a larger reduction ratio, gearboxes usually use multi-stage gear transmission. In multi-stage transmission, each gear transmission will further reduce the speed and increase the torque. By designing the gear ratio of each level reasonably, the output speed and torque of the reducer can be accurately controlled to meet the needs of different working environments.

Energy Conversion Process

Mechanical energy input: The energy input of the reducer usually comes from power sources such as motors, which convert electrical energy into mechanical energy and transmit it to the reducer through the input shaft. At this point, the input mechanical energy mainly manifests as the rotational kinetic energy of the input shaft.

The Conversion and Loss of Energy in Gear Transmission

Conversion: Inside the reducer, as the gears mesh and transmit, the input mechanical energy is transmitted from the input shaft to the output shaft. Due to the decrease in rotational speed, according to the law of conservation of energy, the torque will increase accordingly. That is to say, during this process, a portion of the rotational kinetic energy is converted into greater torque energy, allowing the output shaft to output greater force to drive the load.

Loss: However, in the process of energy transfer, there will inevitably be some energy loss. The main losses include friction losses, oil mixing losses, and bearing losses. Friction loss is caused by the friction between the tooth surfaces during gear meshing and the friction between the shaft and the bearing. These frictions convert a portion of mechanical energy into thermal energy, causing the gearbox to heat up. Oil stirring loss refers to the energy loss generated by stirring lubricating oil when gears rotate in the oil pool. Bearing loss refers to the energy loss generated by the bearing during the rotation of the supporting shaft.