The pneumatic braking system remains quite common on large trucks, especially in Vietnam, due to its low cost and ease of replacing components when failures occur. This study employs two specialized simulation software programs to investigate the pneumatic braking system on a trailer. One software simulates the valve assemblies within the braking system's actuation, while the other simulates the kinematics of the trailer during braking. The results of the investigation demonstrate reliable findings when the braking distance of the trailer is approximately 29 m with a maximum deceleration of about 6.9 m/s2. The pressure build-up time on axles 2–3 and 4–5 is improved by approximately 10%, but this does not significantly affect the vehicle's dynamics. This simulation model is built on two specialized software platforms, making it effective in examining structural parameters as well as the longitudinal dynamics of the vehicle. The modification of structural parameters is performed easily and intuitively. Additionally, the model also allows for the adjustment of specific parameters for individual components within the valve assemblies.