In order to improve the ride comfort of a continuously variable cotton picker, the shift quality of the cotton picker is analysed. Firstly, the transmission principle of the hydrostatic power split continuously variable transmission (CVT) with a single planetary gear set is introduced; secondly, the shift dynamic model of the power train is constructed, and the key models are verified by experiments; finally, the influence law and mechanism of various factors in the shift qualities of a cotton picker are analysed. The results show that the increase in main circuit pressure will reduce the shift quality of the cotton picker; the influence of clutch-charging flow and acceleration rate on the shift quality of the cotton picker can be ignored; with the action time of the clutch delayed in a certain range, the shift impact first decreases slightly, then increases, and finally decreases; the increase in the cotton box weight can slightly improve the shift quality of the cotton picker but is at the cost of consuming more clutch-sliding energy. If different factors are evaluated together, the value of the main circuit pressure and charging flow should not be too large or too small. At the same time, the action time of a clutch to be disengaged should be delayed, and the action time of a clutch to be engaged should be advanced. The conclusions of this study can provide theoretical support for the controller development of a continuously variable cotton picker.

The aim of this study is to enhance the fuel economy of a continuously variable tractor transmission by analyzing its energy and fuel consumption. First, we present the principle of a self-developed tractor transmission based on power splitting and examine its parasitic power characteristics. Next, we construct a mathematical model of the hydraulic system, mechanical system, and entire transmission, calibrating the model to ensure the accuracy of subsequent results. We then perform a systematic analysis of the energy and fuel consumption of the tractor transmission. Finally, we optimize the transmission through design and power matching, investigating the impact of changes in parameters and control strategies on the fuel economy of the transmission. The results indicate that fuel consumption can be reduced by 2%–14% through parameter optimization and by an additional 0%–20% through appropriate power matching.

In order to improve the shift quality of the power reversing tractor, the parameter configuration of the gearbox wet clutch was studied in this paper. Firstly, the transmission principle of the power reversing tractor was introduced; then, the mathematical model of the key parts such as wet clutch, proportional pressure reducing valve and the whole tractor were constructed; thirdly, four clutch control parameters affecting the shift quality were determined, namely, the instruction time $t_{1}$ ∼ $t_{3}$ and the instruction voltage $V_{1}$ of the proportional pressure reducing valve, and the shift quality evaluation index used in this study was determined. Finally, based on four factors and three levels orthogonal test method, the clutch control parameters under different conditions were optimized. The results show that: with the increase of gear, the values of $t_{2}$ and $V_{1}$ should be moderately increased; $t_{1}$ should be larger under any working conditions; $t_{3}$ should be smaller in high or low gear, otherwise the value level should be increased moderately; the driver should try to use power shift at lower gear and engine speed.

In this study, the authors propose a solutions map based on a telomere genetic algorithm (TGA) to improve the efficiency of 4R-linkage synthesis. First, the points on the center curve are obtained by using projective geometry, and those of the circle curve are obtained by vector elimination. Second, the definition of the linkage type, assessment of linkage performance, and a method to identify defects in the linkage are introduced. Third, the solutions map method is proposed that can map the linkage solutions obtained by all combinations of the points on the center curve to a 3D color-coded surface to represent the distribution of solutions with different attributes of linkages in the solution domain. Fourth, we use the proposed telomere operator and pseudo-histogram method to improve the traditional genetic algorithm, and expand the domain of solutions of the solutions map by using the TGA. Finally, the linkage synthesis software BurLink is developed based on the solutions map method. The results show that the TGA-based solutions map can quickly locate the required 4R-linkage solution in the solution domain, and provides engineers with more candidate solutions than traditional methods.

The traction performance analysis of hydro-mechanical transmission (HMT) tractors is employed to evaluate and optimize the transmission system during the design phase, thereby reducing research and development costs associated with continuously variable tractor transmission systems. However, there is currently no established methodological framework for calculating the traction performance of HMT tractors. To address this gap, this study integrated traditional tractor traction performance calculation equations with a self-developed HMT energy consumption calculation method, thereby developing a traction performance calculation model for HMT tractors. Initially, the principle of the tractor’s hydrostatic power-split transmission system was introduced. Subsequently, mathematical models for calculating transmission system energy consumption and tractor traction performance were established, with key sub-models experimentally validated to ensure the reliability of subsequent results. On this foundation, a calculation method for the traction performance of HMT tractors was proposed. Finally, models before and after energy consumption optimization, as well as models under different road conditions and transmission system configurations, were utilized as comparative models to calculate the traction performance of HMT tractors under various settings. The results indicate that energy optimization of HMT not only improves the transmission performance and reduces fuel consumption of HMT tractors, but also enhances the matching capability of HMT tractors with farm tools under high traction efficiency. Additionally, road conditions significantly impact the traction performance of HMT tractors. In wheat stubble fields, the tractor’s traction performance is substantially lower than on standard roads, with a maximum traction force decrease of 40.8% at a slip rate of 30%.