Numerical Modeling of the Critical Operating Conditions for a Hydraulic Lubrication System in a Heavy-Duty Tractor Driveline

This paper analyzes the lubrication system of a heavy-duty tractor driveline in different working conditions by means of a lumped parameter approach. The study highlights the critical areas of the hydraulic circuit that are not sufficiently lubricated and a new system setup is proposed to guarantee an adequate flow rates distribution. The numerical model of the lubrication system combines lumped elements with more complex user-defined components in order to address both the pressure losses due to the geometrical features of the circuit and the specific flow characteristics of the hydraulic components. The model considers several configurations of the system accounting for the rotation rate of the engine and the clutches engagement. The results are validated through experimental comparisons. Several critical issues are identified in terms of insufficient lubricant supplied to the utilities. Consequently, an optimized version of the system is proposed to reach any area of the driveline, thus ensuring the required flow rate at each component and preventing their early damaging. Therefore, this paper highlights the potential of the lumped parameter approach in evaluating the performance of an entire lubrication system and in addressing potential failures.