Self-excited pitch and bounce oscillation occasionally occurs when a tractor pulls a high-draft load on dry soil. This dynamic instability is referred to as the power hop phenomenon. Power hop drastically degrades tractor performance and ride quality and can result in damage to the tractor, operator injury, and soil compaction. Power hop dynamics are characterised by three typical nonlinear elements; i.e., vertical jumping or bouncing, longitudinal stick-slip dynamics, and free-play in the joint between the tractor and implement. This paper couples these nonlinear elements and develops a novel power hop model for time-domain simulation. The occurrence process of power hop was demonstrated using the developed model using numerical experiments. Parametric investigations were conducted varying the drawbar pull, soil, and tyre conditions. The original draft load, joint clearance, static friction coefficient, ratio of coefficients of dynamic and static friction, front tyre stiffness, and rear tyre stiffness were taken as control parameters. The developed model predicted appropriately the occurrence of power hop for a higher draft load, drier soil, and “front stiff and rear soft” tyre stiffness conditions. The results agree obtained with conventional knowledge concerning power hops accumulated by previous experimental research. Thus, the developed model provides a strong platform adopting measures to control and suppress power hops.

当拖拉机在干燥的土壤上拉高起重载荷时，偶尔会发生自激的俯仰和跳动振荡。这种动态不稳定性被称为功率跳变现象。动力跳跃会大大降低拖拉机的性能和行驶质量，并可能导致拖拉机损坏，操作人员受伤和土壤压实。功率跳跃动力学具有三个典型的非线性元素：即，垂直跳跃或弹跳，纵向粘滑动力学以及在拖拉机和农具之间的连接处自由运动。本文结合了这些非线性因素，并开发了用于时域仿真的新型功率跳跃模型。利用数值实验，利用所建立的模型证明了功率跃变的发生过程。进行了参数研究，以改变牵引杆的拉力，土壤和轮胎状况。将原始吃水载荷，接头间隙，静摩擦系数，动静摩擦系数之比，前轮胎刚度和后轮胎刚度作为控制参数。所开发的模型可以适当地预测在较高的吃水载荷，干燥的土壤以及“前硬后软”轮胎刚度条件下动力跳跃的发生。结果与以前的实验研究积累的有关功率跳跃的常规知识一致。因此，开发的模型提供了一个强大的平台，可以采取措施来控制和抑制功率跳变。所开发的模型可以适当地预测在较高的吃水载荷，干燥的土壤以及“前硬后软”轮胎刚度条件下动力跳跃的发生。结果与以前的实验研究积累的有关功率跳跃的常规知识一致。因此，开发的模型提供了一个强大的平台，可以采取措施来控制和抑制功率跳变。开发的模型适当预测了较高的吃水负荷，干燥的土壤以及“前硬后软”轮胎刚度条件下动力跳跃的发生。结果与以前的实验研究积累的有关功率跳跃的常规知识一致。因此，开发的模型提供了一个强大的平台，可以采取措施来控制和抑制功率跳变。