Design and Experimental Study of Direct-Connected Four-Wheel Drive Transmission System for Micro Cultivators

Addressing the critical challenge of energy efficiency loss in micro-cultivator transmission systems within China's hilly terrains, this study develops a direct-connected four-wheel-drive transmission system to enhance efficiency and reliability. Based on agronomic requirements and functional demands for gear positions, a combined gear-chain transmission scheme was implemented, enabling coordinated control between traveling and tilling units, supporting five operational modes, including fast/slow tillage and reverse gear. Through optimized gear parameters and structural configuration, along with carbonitriding treatment and micro-geometry optimization of 20CrMnTi gears, the system achieves significantly improved load capacity and compactness. Integrated validation with KissSoft and Romax that gear safety factors exceed design targets, shaft and bearing lifespan meet the 1,000-hour requirement, and the simulated transmission efficiency of 92.2% surpasses conventional pulley systems. Field verification demonstrates 78.58% soil fragmentation and 90.20% tillage depth stability at a forward speed of 3.46 km/h with a ploughing depth of 22.93 cm, meeting agronomic standards for micro-cultivator operations. This research provides a technical reference for transmission system design in small hillside agricultural machinery.