## 5 Experimental Research
### Experimental Results and Analysis  
1. Steering under the zero-load condition  
Figure 10 shows the comparisons between the traditional steering system and the proposed system under zero-load conditions. In the period of 0\(\sim\)4 s the loader turns to the left, and in the period of 4-8 s the loader turns back to the right. Both the displacements of the steering cylinder pistons show that the loader steering process is correct. As the loader turns to the left first, the right chamber pressure of the steering cylinder is higher than the left. The pressure has a pulse in the traditional system which needs much more energy, while in the proposed system the pressure is much smoother. According to Equations (22)-(24), steering efficiency of the traditional system is 63% and that of the proposed system is 81.6%. This means that the consumption of the system is reduced by 22.8% compared to the traditional system.  
2. Steering under normal load condition  
Figure 11 shows the test curves of the displacement and the pressure of the steering cylinder under the normal load condition. It can be seen that the pressure variation trend of the rodless chamber of both sides of the steering cylinder is similar to that of the zero-load condition. The difference is that the pressure of the high-pressure chamber of the steering cylinder increases compared to the zero-load condition. The maximum pressure of the left steering cylinder when the loader turns to the left is 9.2 MPa, while that under the zero-load condition is 7.5 MPa. The maximum pressure of the left steering cylinder when the loader turns back to the right is 3.9 MPa and the maximum pressure of the right steering cylinder is 7.77 MPa. Based on the test results, the calculated steering efficiency is 90.2%. This means that loader steering efficiency is improved in the normal load condition compared to the zero-load condition.  
Figure 10: Test curves of the traditional system and the proposed system under zero-load conditions.  
3. Steering under offset load condition  
Figure 12 shows the test curves of the displacement and the pressure of the steering cylinder under the offset load condition. It has similar test curves for displacement and pressure, except the pressure fluctuation is larger than the normal load condition. The maximum pressure of the left steering cylinder when the loader turns to the left is 9.4 MPa, while the loader turns back to the right the maximum pressure is 4.3 MPa. The maximum pressure of the right steering cylinder is 8.43 MPa. All the pressures under the offset load condition are larger than those under the normal load condition. Based on the test results, steering efficiency with the offset load is 89.1%, which is lower than that with a normal load.  
4. Steering under different steering speeds  
This experiment is under the zero-load condition to analyze the influence of steering speed on displacement and pressure. Figure 13 shows the displacement and pressure of the steering cylinders with different steering speeds. With the increase of steering speed, the steering time decreases accordingly. The displacement of the steering cylinder with a high steering speed is a little shorter than the other two steering speeds. The maximum pressures of the steering cylinders are almost the same for the three different steering speeds. Steering efficiency under the low steering speed, medium steering speed, and high steering speed is 81.2%, 81.6%, and 82.5%, respectively. This indicates that the higher the steering speed is, the higher the steering efficiency can become.  
Figure 11: Test curves of steering with a normal load.  
Figure 12: Test curves of the steering with offset load.