At present, most agricultural tractors in China use mechanical gear transmissions, which use meshing sleeves or synchronizers to shift gears. The selection of gears is less and the driver needs to judge the shift time according to experience, which is easy to waste engine power and improve the working intensity of the driver. Because tractors are mainly operated in the field, the southern region of China is mostly hilly terrain, which is complex and rugged, leading to a high degree of complexity of the tractor working environment, so the requirements for the gears of tractors are also increasing.
At the same time, with the progress of science and technology and economic development, tractors are not only used in light load operations such as farming, but also used in production and life as transportation or load tools. These different working conditions require different gears to meet their needs, that is, under the condition of saving engine power, the change of external load can be matched by changing the speed and torque output by the gearbox. The transmission design requirements shall meet the following conditions:
(1) Ensure that the tractor has sufficient reliability and high efficiency when working;
(2) Design neutral gear and reverse gear;
(3) Equipped with power output end;
(4) The volume design of the gearbox shall be as small and economical as possible.
The design input conditions obtained according to the above conditions and actual use requirements are shown in the table.
| Design elements | Target value |
| Forward gear speed range/km/h | 2-40 |
| Design gear | 16+8 |
| Engine rated power/kW | 95 |
| Rated engine speed/(r/min) | 2 000 |
| Rated torque/N · m | 450 |
| Total weight/kg | 1 800 |
| Tyre diameter/mm | 1 500 |
| Rear axle transmission ratio | 14.2 |