In order to facilitate the calculation and accurately reflect the actual working environment of the gearbox, the working environment of the gearbox should be approximately simulated through boundary treatment. For example, rbe2 unit is used to simulate the connection between tractor gearbox housing casting and engine bolt, and the connection between tractor gearbox housing casting and rear axle bolt. As shown in Figure 1. Because the outer ring of the bearing is closely connected with the bearing hole and the inner hole of the bearing is closely connected with the shaft, rbe2 element is also used to simulate the bearing in this paper. As shown in Figure 2. Restrict the degrees of freedom of the rbe2 unit connected between the box and the engine and the rbe2 unit connected between the box and the rear axle.
The load on the casting of tractor gearbox shell can be divided into three parts: the first part is the self weight of the shell. The application of self weight load can use the grav card to define the size and direction of gravity, and the program will automatically convert it into the load force of each node according to the setting; The second part is the force generated by the internal gear meshing transmission. According to the working condition analysis, when the tractor gearbox shell casting is in the first gear and reverse gear working conditions, the transmission ratio is the largest and the gear meshing transmission torque is the largest. Therefore, the tractor gearbox shell casting is the most stressed. Therefore, these two working conditions are selected for static analysis; The third part is to consider the influence of other parts on the casting of tractor gearbox housing according to the connection mode of tractor parts. Finally, the three parts of the load are combined through the load card.
According to the tractor product specification confirmation table, the actual working parameters of the gearbox are obtained and the actual load is calculated. The rated output power of the engine is 110.3kw. As shown in the table, the tractor transmission system has 16 forward gears and 8 reverse gears.
| Gear | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
| Forward | 1.37 | 1.83 | 2.26 | 2.39 | 3.02 | 3.94 | 4.66 | 5.86 | 7.69 | 7.84 | 9.67 | 10.24 | 12.94 | 16.90 | 19.95 | 32.94 |
| Retrogression | 2.09 | 2.80 | 3.66 | 7.14 | 8.98 | 12.02 | 15.69 | 30.58 | — | — | — | — | — | — | — | — |