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In this paper, a hybrid roll control system, including passive and active roll control units, is designed to improve the roll dynamics of tanker vehicles and to reduce the lateral shifts of the liquid cargo due to lateral accelerations. The passive control system consists of radial partitions installed inside the vehicle container. These partitions rotate in phase with the liquid cargo as one unit about the longitudinal axis of the container in response to the induced momentum forces due to the lateral acceleration excitation. Torsion dampers are fixed between the partitions and the container's front and rear walls to reduce the oscillating motion of the liquid cargo. While the passive partition dampers control the dynamics of the liquid cargo inside the container, the dampers of the vehicle suspension are switchable, generating anti-roll damping moments based on the lateral acceleration level and the container filling ratio.

This work describes a 3 dimensional modeling technique for investigating the random response of tractor semitrailer systems considering different types of fifth wheels and their kinematic constraints. The inputs to the vehicle model are the power spectral density (PSD) of the vertical road irregularities considering different road types. In addition to the time delay axle correlation, the cross correlation between the left and right tracks is modeled using the coherence function. The masses of the driver/seat assembly, tractor, semi-trailer and wheel/axle assemblies as well as their suspension elements are considered in the vehicle model. The possibility of reducing the roll accelerations of both tractor and semi-trailer by using a compensating fifth wheel (articulation) has been studied. The designed fifth wheel is a fully oscillating unit. Using this fifth wheel, the tractor and semi-trailer could oscillate relatively in the pitch and roll directions.

Recently, the application of active suspension systems in commercial vehicles is recommended to reduce road damages due to the generated dynamic tyre loads and to improve ride quality, structure safety and both handling and traction stability. The purpose of this paper is to design suspension controllers for a tractor semi-trailer system considering chassis elasticity and the controller time delay. The modal parameters of the vehicle chassis as a separate free-free substructure (connected tractor and semitrailer frames) are calculated using the finite element method and then incorporated with the rigid parameters and motions of the whole vehicle components. The connection (articulation) between the tractor and semitrailer frames is modeled by a vertical spring with its ends attached to the tractor and semitrailer frames.

It is well known that the excessive levels of vibration in heavy vehicles negatively affect driver comfortability, cargo safety and road condition. The current challenge in the field of suspension design for heavy vehicles is to optimize the suspension dynamic parameters to improve such requirements. Almost all of the previous work in this field is based on applying the mathematical optimization considering active or passive suspension systems to obtain the optimal dynamic parameters. In this work a new passive suspension systems for heavy trucks is suggested and compared with the conventional passive suspension systems. The new systems rely on transferring the vertical motion, (vibration), into horizontal motion through a bell-crank mechanism to be taken by a horizontal passive suspension system. The system dynamic parameters like body acceleration, suspension travel and dynamic tire load are calculated assuming random excitation due to road irregularities.

The present paper presents design considerations for a new tandem suspension system equipped with hydro-pneumatic components. The theory of the new suspension and its configuration were presented in a previously published SAE paper, [1]. In this design, most of the vertical motions were transformed into horizontal motions through two bell cranks. A hydraulic actuator is installed horizontally between the bell cranks and connected to an accumulator (gas spring) via a flow constriction (damper). Incorporating of hydro-pneumatic components in the new suspension system exhibits simple and applicable design. Moreover, further developments including active or semi-active vibration control systems, can be applied directly using the existing hydro-pneumatic components. Mathematical models are constructed to simulate the vehicle ride dynamics. Equations of motion are generated considering a conventional passive suspension (four springs tandem suspension) and the new designed suspension system.