Oil film separation and drag torque in disengaged wet brakes

Multi-disc wet brake packs are commonly used for off-highway applications. Unfortunately when disengaged, these components can create significant levels of unwanted parasitic losses. This paper presents a novel, validated model to predict the parasitic losses in disengaged multi-disc wet brake packs. The model employs pertinent boundary conditions to determine the position of the free boundary created by oil film separation. The experimental and analytical results demonstrate the significance of wet brake disengaged losses at a range of angular velocities, typically found in operation. The improved understanding accrued by the expounded time-efficient methodology presents significant opportunity to develop predictive toolsfor driveline system efficiency calculations and component design optimisation for off-highway vehicles.