Design and Simulation of a Pneumatic Test-Bench for Locomotive Brake Valves

Pneumatic braking systems are critical for the safe and reliable operation of locomotives. However, conventional brake valve testing utlizing onboard locomotive brake panel can be highly time-consuming as the valve must be fully reinstalled before the leakage behaviour can be verified. To adress this challenge, this study develops a simulation-based pneumatic test-bench model to evaluate locomotive brake valve pressure retention and leakage behaviour. The model was developed using MATLAB/Simulink and Simscape Fluids incorporating components such as a compressed air reservoir, flow restriction, brake cylinder chamber, leakage orifice, atmospheric reservoir, pressure sensor, gas properties, and solver configuration. Validation of the model was based on the KTMB Class 26 independent brake cylinder leakage test protocol, which requires the system pressure to remain above 3.6 bar for 1800 seconds after being initially charged to approximately 3.90 bar. Under normal operating conditions, the simulated pressure decreased from 3.90 bar to 3.79 bar, resulting in a PASS clasification. Converseley, under simulated leakage conditions, the pressure decreased from 3.90 bar to 2.95 bar resulting in a FAIL clasification. The results show that the proposed simulation model can distinguish between acceptable and excessive leakage behaviour, thereby supporting early-stage brake valve leakage analysis prior to physical prototype development.