Abstract: Aiming at the complex problem that the running stability of passenger trailer combination is affected by multiple parameters of trailer and the parameters are interrelated,a comprehensive parameter called mass distribution coefficient is analyzed. Firstly, a passenger trailer combination dynamics model is established. Combined with the impact center theory and parallel axis theorem,the mass distribution coefficient integrating trailer mass,moment of inertia, center of mass position and axle position are derived. Then a passenger trailer combination simulation model is established in the TruckSim software, and the validity of the simulation model is verified through real vehicle tests. Finally, by adjusting tongue weight and moment of inertia simulation and model car test, the relationship between the mass distribution coefficient and driving stability are investigated. The simulation and test results show that the mass distribution coefficient varies from 1.1 to 3.4 and the rear amplification coefficient varies from 0.9 to 1.5. The smaller the mass distribution coefficient is,the smaller the rear amplification coefficient of the passenger car train will be. Therefore,the mass distribution coefficient has a strong correlation with the running stability. The smaller the mass distribution coefficient,the better the running stability of the passenger trailer combination.

Key words: passenger trailer combination, heavy tongue, rotational inertia, mass distribution coefficient