Improving the stability and handling of tractors when towing trailers and coupled units

BACKGROUND: Currently, almost all agricultural work is performed using tractors. As the transport speed of a tractor train increases, the amplitude of lateral and horizontal oscillations of its coupled units emerges and increases. At certain velocities, these oscillations become so large that they can lead to a rollover, in addition, shock loads occur in coupling devices, which make it difficult to handle a tractor train. The traditional method to prevent this is the velocity limit, which does not guarantee a positive result.

AIMS: Development of methods to improve stability, handling and safety of wheeled tractor trains by reducing the galloping and yawing of a truck tractor when towing heavy loads.

METHODS: The following options of the design of the system for countering the occurrence of self-oscillations in the design of a wheeled tractor train ensuring a reduction in the level of self-oscillations, increasing the stability, handling and safety of the tractor train have been proposed: the coupling device equipped with hydraulic damping devices operating at longitudinal and lateral folding; the control system for the individual traction electric drive of a truck tractor preventing the loss of wheel grip with the ground surface; the combined use of the control system for the individual traction electric drive of a truck tractor and the coupling device equipped with hydraulic damping devices; the combined use of the coupling device equipped with hydraulic damping devices and a steering correction system.

RESULTS: With use of simulation modeling methods, it has been established that the coupling device equipped with hydraulic damping devices adjustable by the folding angle of the tractor train and by the yaw angle oscillations of a truck tractor body should be recognized as the most acceptable and effective system for reducing self-oscillations of a wheeled tractor train at the current state of the art.

CONCLUSIONS: The practical value of the study lies in the possibility of using the proposed methods to eliminate the risk of self-oscillating processes in the design of promising types of agricultural machinery.