To comparative assessment of three-unit lorry passenger trains

Abstract

In the modern automobile industry when creating multi-trailers auto-trains, including passenger trains, the question of the choice of trailers is urgent and it is actively discussed in the literature. There are two main schemes of multi-trailers auto-trains - trailed and semi-trailed. In the trailed diagram, each trailer rests on its axes, in the semi-trailed one - both on its axes and on the axis of the previous trailer (articulated buses and trolleybuses). The theoretical foundations of the analysis are based on mathematical models of straightforward and controllable car and auto-train movements, which are designed for cars, two- and three-trailed auto-trains.
However, their application to three-trailed metrobuses is problematic due to the different layout of the auto-trains and metrobuses, different loads on individual trailers, different control systems, etc. Hence the problem of predicting the agility and stability of the movement of three-trailed metrobuses during their movement both in the general traffic flow and on specially allocated lanes, which determined the purpose and objectives of the study. The purpose of the work is to improve the stability of the three-trailed metrobuses by choosing a rational layout scheme and design parameters of its trailer.
According to the purpose, the tasks of the study were defined, for which the metrobus was presented in the form of three modules - a bus and two trailers. For such a metrobus, differential equations of plane-parallel motion were recorded, the solution of which allowed us to determine the critical speed of movement and to carry out a comparative analysis of different layout schemes of metrobuses for stability of movement.
Due to the fact that the traffic of metrobuses is carried out on separate lanes with a speed of 25 ... 30 m / s, the influence of the design parameters of the bus and trailers on the value of the critical speed of movement is analyzed. It is established that the increase of the transverse horizontal stability of the metrobus is positively affected by the reduction of the air pressure in the front axe tires and the increase in the rear axe tires of the first trailer (semi-trailer), the displacement of the center of mass of the trailers to the front axe, the increase of the coefficients of lateral tire deflection of the wheels (semi-trailer), increasing the mass of the bus and the first trailer, etc. The influence of other parameters is either negligible or nonexistent. However, judging in general the stability of movement only at a critical speed movement is not enough. Consideration should be given to the stability of the metrobus in transient driving modes when performing various maneuvers. This may be the subject of further research.
Key words: metro, bus, trailer, semi-trailer, equation of motion, stability, speed, assembly angles, controls.