Performance Evaluation of an Air–Oil Brake System in Straw-Thresher Combines Compared to Hydraulic Systems

The brake system in straw-thresher combines plays a crucial role in operational safety and machine control under field working conditions. The objective of this study was to design, construct, and evaluate the performance of a simultaneous air–oil brake system for a straw-thresher combine and to compare it with the conventional fully hydraulic brake system. In this study, a simultaneous air–oil brake system was designed and fabricated for a straw-thresher combine. In the proposed system, air pressure is first applied to the brake shoes and pads, followed by hydraulic pressure as a booster in the circuit. Field experiments were conducted at three working speeds (۵, ۶, and ۷ km/h) and three grain tank load levels (۶۰%, and ۱۰۰% of capacity). The results showed that the average stopping time of the combine decreased from ۲.۲۸s in the fully hydraulic system to ۱.۷۵s in the air–oil system. Braking distance was also reduced from ۱۸.۰۵m to ۱۰.۲m, and the standard deviation of braking force decreased by approximately ۲۷%. Statistical analysis confirmed a significant difference between the two systems at the probability level of p < ۰.۰۵. Numerical simulation also indicated a reduction in stress concentration in the disc and brake pad assembly. The findings of this study demonstrated that the simultaneous air–oil brake system provides superior and safer performance compared to the fully hydraulic system in straw-thresher combines and can serve as a reliable option for the design of future combines.

کلیدواژه ها:

Agricultural Machinery Safety ، Air–Oil Brake System ، design ، Hydraulic Braking ، Simulation ، Straw-Thresher Combine