JAUTO-17-0287 Accepted.pdf (924.56 kB)

Efficiency of disengaged wet brake packs

Download (924.56 kB)
journal contribution
posted on 06.02.2018, 14:58 by Michael Leighton, Nick Morris, G. Trimmer, Paul King, Homer Rahnejat
Key objectives in off-highway vehicular powertrain development are fuel efficiency and environmental protection. As a result palliative measures are made to reduce parasitic frictional losses, whilst sustaining machine operational performance and reliability. A potential key contributor to the overall power loss is the rotation of disengaged wet multi-plate pack brake friction. Despite the numerous advantages of wet brake pack design, during high speed manoeuvre in highway travel or at start-up conditions significant frictional power losses occur. The addition of recessed grooves on the brake friction lining is used to dissipate heat during engagement. These complicate the prediction of performance of the system, particularly when disengaged. To characterise the losses produced by these components, a combined numerical and experimental approach is required. This paper presents a Reynolds-based numerical model including the effect of fluid inertia and squeeze film transience for prediction of performance of wet brake systems. Model predictions are compared with very detailed combined Navier-Stokes and Raleigh-Plesset fluid dynamics analysis to ascertain its degree of conformity to representative physical operating conditions, as well the use of a developed experimental rig. The combined numerical and experimental approach is used to predict significant losses produced during various operating conditions. It is shown that cavitation becomes significant at low temperatures due to micro-hydrodynamic action, enhanced by high fluid viscosity. The magnitude of the losses for these components under various operating conditions is presented. The combined numerical-experimental study of wet multi-plate brakes of off-highway vehicles with cavitation flow dynamics has not hitherto been reported in literature.


The authors would like to express their gratitude to J. C. Bamford Excavators and Innovate UK for their financial support of the reported research.



  • Mechanical, Electrical and Manufacturing Engineering

Published in

Proc. IMechE, Part D: Journal of Automobile Engineering


LEIGHTON, M. ... et al, 2018. Efficiency of disengaged wet brake packs. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 233 (6), pp.1562-1569.


© IMechE. Published by Sage


AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Acceptance date


Publication date



This paper was accepted for publication in the journal Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering and the definitive published version is available at https://doi.dox.org/10.1177/0954407018758567