Systemic Modelling and Simulation Approach to Estimate Brake Response Time in a Pneumatic Brake Systems

Brake response time in truck air brake systems is crucial for ensuring safety and operational efficiency. This paper details the development of a simulation model aimed at fulfilling all regulatory requirements for brake response time, as well as serving as a tool for stopping distance calculations. The actual pneumatic circuit, including brake valves, relay valves, brake chambers, and plumbing have been replicated. The aim is to use 1D simulations to predict the response time compliance during the pressurizing phase (when brakes are applied) of the brake system. A mathematical model is developed using a commercially available 1D simulation tool. This model employs a lumped parameter approach for the pneumatic components, with governing equations derived from compressible flow theory and empirical valve flow characteristics. The simulation outcomes provide detailed response time and pressure build-up profiles. Validation against 201 vehicle test cases showed 96% of simulations within ±10% of measured response times, aligning with FMVSS thresholds. These results confirm the model’s predictive accuracy and its value in optimizing brake system design while reducing physical testing. Overall, the proposed approach offers actionable insights to optimize air brake designs during the development phase, thereby, significantly reducing the need for expensive testing.