SIMULATION OF EMERGENCY OPERATION OF VEHICLE GEARBOX VARIATOR

The relevance of the work stems from the necessity to ensure reliable functioning of a continuously variable transmis-sion (CVT) under emergency conditions, particularly when the hydraulic control system fails. The aim of the study is to define the operational characteristics of a chain-type variator of CVT without hydraulic control. The method of the work is computer modelling of the chain variator. The novelty of the work lies in utilizing a discrete contact model between the chain and conical pulleys of the variator, accounting for variations in friction parameters. As a result, a computer dynamic model is developed to evaluate the performance characteristics of a chain-type variator in a con-tinuously variable gearbox lacking hydraulic control. The author finds that increasing torque on the driving pulley leads to increased angular velocity ratio between the pulleys. For the pulleys to reach maximum gear ratio position, the spring force pressing the cones against the chain must be greater on the driven pulley compared to the driving pulley. Contact lines between the chain axes and pulley surfaces do not follow circular arcs due to elastic deformation of contact bodies and changes in chain tension force in the contact zone. Midway along the line of contact between the chain and the driving pulley, the distance from the chain to the pulley axis decreases. Similarly, the distance from the chain to the axis of the driven pulley diminishes as chain tension force increases.