Journal of Agricultural Machinery Engineering ISSN:2799-8673(Print) 2799-8819(Online) 농업기계공학

This study analyzed the equivalent load of the driving unit of a self-propelled garlic and onion collector to quantify the effect of load variability on fatigue design of the driveline. Field experiments were conducted under 18 operating conditions combining two crops (garlic and onion), three engine speeds (2000, 2300, and 2600 rpm), and three travel speeds (0.1, 0.2, and 0.3 m/s). Left and right sprocket torques were measured using strain gauge–based telemetry, and the 1× and 2× rotational harmonic errors caused by the single-sided gauge placement were removed in the frequency domain while preserving the actual work-load components. Equivalent torque and equivalent rotational speed were calculated based on Miner’s rule with eight load bins and a fatigue damage exponent of 3 (ISO 6336-6). The ratio of equivalent to mean torque exceeded unity under all conditions (1.015–1.123 for the left and 1.005–1.050 for the right sprocket) and remained stable across crops and operating conditions, whereas the mean torque itself varied more strongly with the operating condition. Although the equivalent torque exceeded the mean by at most 12.3%, mean-based design overestimated fatigue life by up to 29.4% owing to the cubic dependence of fatigue damage on load. These results indicate that the load variability of the driveline can be represented by a stable side-specific correction factor, while determining a single representative design load requires additional duty-cycle information on operating conditions.