Designing Method Of Dual Front Axle Equalizing Suspension For Truck

To improve the truck transport efficiency, we should, on the one hand improve the load capacity by reduce the assembly weight and increase the cargo body volume, on the other hand select the assembly which has good loading capacity according to the purpose of vehicle. Without the great improvement of material and technology, it is limited for the engineer to do the design work only by reducing the assembly weight or selecting the proper assembly. Therefore many manufacturers improve the load capacity by adding the axles and tires under the stress of the improving chassis loading capacity and the limited axle permitted load.The multi-axle vehicles, because of the weight is supported by many tires, have the wider touching ground area and less actual deformation. So that the towing force can be increased well the power performance, the traffic ability, the fuel economy, the handling stability and the vehicle safety can be improved.The equalizing suspension is generally used on the multi-axle vehicles to guarantee the equal distribution of the load on every wheel. It enhancing the ground contact capacity and the traffic ability for heavy-duty vehicles, and improving the force conditions for every vehicle wheel. The equalizing suspension connects the front-axle suspension systems or the rear-axle suspension systems by using the equalizing mechanism to guarantee the equal vertical load on the two vehicle axles under any circumstance. The dual front-axle equalizing suspension could ensure a good handling ability for steering wheels. The dual rear-axle equalizing suspension could ensure a adequate towing force for driving wheels.At present, the application of the dual rear-axle equalizing suspension in domestic is for many years well the system structure and design method are becoming more and more considerate. However, the application of the dual front-axle equalizing suspension is on the early stage because most of them adapt the non-connected dependent suspension. Therefore the design method research of the dual front-axle equalizing suspension will have the significant meaning for the future use and population.The dual front-axle equalizing suspension can guarantee the equal or similar load for the first and the second axle even if the two axles have the very different height. By ensuring all the tires have the equality load, the wear of tires will be alleviated obviously. And the uniformity distribution of the vehicle break force will improve every performance index under the bad driving conditions.Compared with the traditional front suspension, the dual front-axle equalizing suspension has added the equalizing mechanical. For the analysis to the similar structure, we generally use the ADAMS modeling to do the analogue computation for motion path and loading change. This computation method can bring a perfect effect, but it needs to input the parameters in initial stage and has a pretty long modeling period. So this method is not suitable to most automotive designers.The first part of this article, we have studied the application of the dual front-axle equalizing suspension in the foreign countries. As first, we analyzed four kinds of dual front-axle equalizing suspension structures of Mercedes-Benz (Actros 4140 series), Mitsubishi (FUSO KC-FS519VX series), DAF (FAX CF85 series and R series), then compared the force conditions, complexity degrees and the general levels for the four structures.After that, we built the kinematics modeling and dynamic modeling separately for the four kinds of dual front-axle equalizing suspension, deduced the dynamic formulations for every key hinge point by using the relative theories of plane geometry, then analyzed the force conditions for every key parts by using the three-force balancing join theorem and parallelogram rule, finally provided the computation method for every structure. We also gave the comparison of the dynamic characters and force characters between the two kinds of suspension structures according to the models.The kinematics modeling and dynamic modeling of the dual front-axle equalizing suspension are very complicated for including so many physics parameters, such as: the force, the displacement and the angle, etc. If we do not carry out the simplifying work for that, we will have to not only face the complex computation, but also do nothing with the consequent designing work for suspension. Therefore, simplifying the proper modeling and providing the simple computation method will have the significant guidance for popularizing the application for dual front-axle equalizing suspension, especially for the suspension's initial layout and design.The second part, integrating the suspension structure characters with the automobile design requirements in domestic, we built the simplified model for the dual front-axle equalizing suspension on the basis of Mercedes-Benz model. Furthermore, the model has been carried out the full-scale test to the chassis of Mercedes-Benz Actros 4140 and passed with ADAMS approval.For the convenient of the engineer to grasp the design method more easily, we will take the FAW vehicle as example on the basis of simplified kinematics modeling and dynamic modeling, present the design points for the dual front-axle equalizing suspension including the design input condition, design target, the layout and structure optimization, component movement check, computation for the main parts. The engineer shall complete the design work for dual front-axle equalizing suspension according to the above points.The research work of this article is base on both the foreign advanced experience and the domestic actual conditions. It is the basic theory for designing the dual front-axle equalizing suspension and fills in a gap of domestic research, provides the relevant basis to research work in future. Taking it as a foundation, we have also carried out the research of optimization method and the interface between the mathematics modeling and three-dimension modeling.