A directional dynamic model of a partially filled liquid tank vehicle is developed to investigate its dynamic characteristics during typical straight-line braking maneuvers. The computer simulation model is developed by integrating the fluid slosh model of a partially filled tank to the pitch plane vehicle model. The dynamic behavior of liquid within the tank is modeled using an equivalent mass-spring system. The analogous mechanical system model for the partially filled cleanbore cylindrical tank is developed by utilizing the potential flow theory for longitudinal oscillations. An approximate summation method is developed in order to obtain the mechanical system parameters and are validated against experimental results available in literature. Computer simulation of the tank vehicle for typical braking maneuvers is then performed by incorporating the slosh forces and moments computed using the mechanical analogy model into the vehicle model. The dynamic normal loading conditions on various axles during a braking maneuver are then computed using the analogous mechanical system approach and are compared to those obtained using a steady-state fluid model in order to investigate the influence of fluid slosh behavior. Influence of the various tank and vehicle design parameters on the dynamic behavior of the tank vehicle is also investigated for various braking maneuvers. The study presents a novel approach to investigate the braking behavior of partially filled tank vehicles.