Replicating the rolling-sliding dynamics of cam-roller contacts in large-scale hydraulic drivetrains: A small-scale approach

The rolling-sliding dynamics of large-scale cam-roller contacts are strongly influenced by the inertia of the roller, particularly when slippage occurs. Slippage can potentially impact the reliability of these rolling interfaces. This study introduces an approach to replicate the rolling-sliding dynamics of cam-roller contacts in a large-scale hydraulic drivetrain, on a small scale. For that, we have upgraded our two-roller tribometer to enable cyclic loading, allow the application of resisting torques, and generate inertia torques. These are three essential elements required to mimic the dynamics observed at large scales. A method has been proposed for scaling the roller inertia accordingly. Furthermore, we have implemented a modeling framework from previous work to make predictions under various dynamic conditions. The results show that our small-scale approach can replicate five key characteristics anticipated at a large scale, including those linked to slippage. Small increments in the resisting torque significantly increased the slide-to-roll ratio (SRR) and peak traction force, among others. The simulations also predicted these effects, capturing trends and producing reasonable predictions of the magnitude and relevant features of key parameters. The use of cyclic loading, extra inertia, and adjustable resisting torques, effectively generated repeatable and controllable dynamic rolling-sliding conditions. Our work is significant for the design and development of novel large-scale hydraulic drivetrains. Our findings highlight the importance of reducing slippage at low contact forces to prevent the brusque change in the rolling conditions during the high contact force phase. By doing so, surface damage and detrimental dynamic effects can be prevented.