Replicating the rolling-sliding dynamics of cam-roller contacts in large-scale hydraulic drivetrains

Abstract

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.