# Research on the Influence of Tractor Parameters on Shift Quality, Based on Uniform Design
## 3 Simulation Analysis of the Shift Process
### Analysis on the Influence of Tractor Parameters on the Shift Quality (Range 1 to Range 2)
#### 3.4.1 The Shift Process under the Influence of a Single Parameter  
1. Engine speed The simulation condition can be expressed as follows: \(F_{r}=5\) kN, \(P_{c}=2\) MPa, \(D_{o}=3.5\) mm. Six tests were conducted at engine speeds of 1000 r/min, 1200 r/min, 1400 r/min, 1600 r/min, 1800 r/min, and 2000 r/min. The test results are shown  
Figure 5: Powertrain simulation model.  
Figure 6: Simulation results of the continuous shift process of HMCVT. (**a**) Simulation result of the tractor linear velocity; (**b**) Simulation result of the jerk of the output shaft.  
in Figure 7a. In general, the acceptable jerk value increased with the engine speed during the shift process. The shift time decreased with the increase in engine speed, and did not change after 0.24 s. Therefore, the engine speed had a significant effect on the acceptable jerk and shift time.
2. Tractive resistance of the tractor The simulation condition can be expressed as follows: \(N_{e}=2000\) r/min, \(P_{c}=2\) MPa, \(D_{o}=3.5\) mm. Six tests were conducted at the tractive resistances of the tractor of 5 kN, 8 kN, 11 kN, 14 kN, 17 kN, and 20 kN. The test results are shown in Figure 7b. The acceptable jerk value increased with the increase of the tractive resistances of the tractor during the shift process; the shift times were all 0.24 s. Therefore, the tractive resistance of the tractor had no effect on the shift time, but it had a significant effect on the acceptable jerk.
3. Clutch oil pressure The simulation condition can be expressed as follows: \(N_{e}=2000\) r/min, \(F_{r}=5\) kN, \(D_{o}=3.5\) mm. Six tests were conducted at the clutch oil pressure of 2 MPa, 1.8 MPa, 1.6 MPa, 1.4 MPa, 1.2 MPa, and 1 MPa. The test results are shown in Figure 7c. The acceptable jerk value decreased with the decrease of clutch oil pressure during the shift process. The shift time varied with the change of the clutch oil pressure during the shift process, but it did not reflect the regularity. Therefore, the clutch oil pressure had an irregular impact on the shift time and had a significant impact on the acceptable jerk.
4. Office diameter The simulation condition can be expressed as follows: \(N_{e}=2000\) r/min, \(F_{r}=5\) kN, \(P_{c}=2\) MPa. Six tests were conducted at the orifice diameters of 3.75 mm, 3.5 mm, 3.25 mm, 3 mm, 2.75 mm, and 2.5 mm. The test results are shown in Figure 7d. The acceptable jerk value decreased with the decrease of the orifice diameter, but if the orifice diameter was too small, it caused an increase in the acceptable jerk value. The shift time increased with the decrease of the orifice diameter. Therefore, the orifice diameter had a significant effect on the shift time and the acceptable jerk.  
Figure 7: The test results of a single parameter. (**a**) The test results of the engine speed; (**b**) The test results of the tractive resistance of the tractor; (**c**) The test results of the clutch oil pressure; (**d**) The test results of the orifice diameter.