Showing papers on "Rollover published in 1988"

Roll Plane Analysis of Articulated Tank Vehicles During Steady Turning

Abstract: SUMMARY The rollover immunity levels of articulated tank vehicles with partial loads are investigated. A static roll plane model of the articulated vehicle employing partially filled cylindrical tank is developed. The vertical and lateral translation of the liquid cargo due to vehicle roll angle and lateral acceleration, encountered during steady turning, are evaluated. The roll moments arising from vertical and lateral translation of the liquid cargo are determined and incorporated in the roll plane model of the vehicle. The adverse influence of the unique interactions of the liquid within the tank vehicle, on the rollover limit of the articulated vehicle is demonstrated. The influence of compartmenting of the tank on the steady turning roll response of the vehicle is analyzed, and an optimal order of unloading the compartmented tank is discussed.

Head support for vehicle seats

Abstract: A head support for vehicle seats includes a vertically adjustable head support cushion which can be fixed to the limbs of a U-shaped frame which is formed, according to the invention, by a rollover bar, which is assigned to the individual vehicle seat and is supported behind the latter by the floor of the vehicle.

Multiple Steered Axles for Reducing the Rollover Risks of Heavy Articulated Trucks

Abstract: This paper presents an analytical study of the performance improvements that can be obtained at both high and low speed using multiple steered axles on heavy articulated trucks. At high speed, rollover usually represents a worst case scenario. Therefore we have chosen to evaluate possible steering designs based on their ability to reduce lateral acceleration of the semitrailer center of gravity. This is in contrast to passenger cars where four wheel steering has typically been evaluated based on measures that were thought to be related to driver acceptance. This paper also investigates the effects of steering rear tractor axles on the low speed manoeuvrability of the vehicle. Steering algorithms for the rear tractor tyres were evaluated using frequency response and simulation of an obstacle avoidance maneuver. Results indicate that at high speeds considerable reductions in trailer lateral acceleration can be obtained during transient manoeuvres. At low speeds, steering of the rear axles demonstrated improvements in manoeuvrability. More work is needed to determine if drivers are able to effectively make use of these improvements indicated by the open loop models, and to evaluate the practicality and cost of implementing these systems (A).

Improving the dynamic performance of multi-trailer vehicles: a study of innovative dollies

Abstract: The research approach taken was to examine the dynamic performance of a typical commercial vehicle when equipped with each of 4 dolly types (the trapezoidal dolly, the linked-articulation dolly, the self-steering B-dolly, and the controlled-steering B-dolly), and then to compare this performance with that when it is equipped with a conventional A-dolly. The performance measures of rearward amplification, dynamic rollover threshold (the point of no return where a rollover could take place), and yaw damping (the quality that suppresses unstable yaw response) were used in this comparison. The findings indicate that B-dollies are dynamically superior to A-dollies and other types of innovative dollies because of the roll coupling between the leading semitrailer and the dolly, and the possibility of steering the dolly wheels to achieve good trailing fidelity of the last trailer.

Method for controlling at least one drive element of a motor vehicle rollover bar and device for implementing the method

Abstract: A method and a device are disclosed for jointly actuating drive elements of a rollover bar which can be raised and lowered, a folding hood and side windows, which can also be operated independently by remote control, of a convertible or roadster-type vehicle, it being possible to control, by manual actuation of only one of the electrical control switches assigned to the folding hood control system, a sequence of movements which is co-ordinated by means of signals from the end position switches which are assigned to the moving parts, which sequence of movements prevents collisions between the moving components, especially between the folding hood on the one hand and the rollover bar and/or the side windows on the other within an area of motion, the device, in addition, having another common power sources for the hydraulic drive elements of the folding hood, a hood box lid, the blocks assigned to the latter and the rollover bar.

Sensitivity analysis of vehicle tripped rollover model

Abstract: The time domain sensitivity analysis of System Technology Incorporated's (STI) Tripped Rollover Vehicle Model has been conducted utilizing sensitivity programs developed by the University of Missouri-Columbia. The eight degree of freedom STI tripped rollover model simulates the motion of a vehicle which skids laterally on pavement and then impacts with a curb. The sensitivity of vehicle system parameters and relevant system response variables have been investigated and ranked in order of importance. Based on energy considerations, vehicle rollover prevention energy reserve (RPER) has been derived and used as an indication of vehicle rollover stability. The results reveal that the minimum value of RPER approaches zero at the threshold of rollover and if the minimum falls below zero then vehicle rollover will occur.

Reducing the risk of spillage in the transportation of chemical wastes by truck

Abstract: The spillage of liquids in bulk quantities during transportation is examined from the viewpoint of the risk reduction which will result from improved vehicle roll stability Roll stability limits were first computed for conventional vehicles used currently by the Rohm and Haas Company to transport chemical waste products The vehicles in question included tractor-semitrailer combinations having both van- and tank-type trailer configurations The stability level of individual vehicles was related to a national rate of rollover risk, expressed in rollovers per million miles of travel The risk projections were based upon an evaluation of accident and exposure information generated through a detailed survey program undertaken previously Improvements in suspension selection, height of the payload center of gravity, and tractor axle width were also examined by means of the stability analysis When used in combination, such improvements were seen to reduce the rollover risk by as much as 35% relative to Rohm and Haas' current equipment The problem of fluid slosh occurring when a bulk tanker is underfilled was also considered by reference to existing literature

Measurement of heavy vehicle suspension roll stability properties, and a method to evaluate overall stability performance

Abstract: The suspension properties influencing the roll stability of heavy duty vehicles are identified, and the fundamental mechanics of how they influence rollover are discussed. Test procedures for measuring these suspension properties using a tilt table device and a cable actuator setup are also discussed. In addition, results of a sensitivity study using a static rollover computer model are provided which illustrate how changes in each suspension property influence vehicle rollover. Lastly, a method of combining the results of the sensitivity study to determine how the suspension properties together influence vehicle rollover is given. This method allows easy comparison of the overall roll stability performance of different suspensions (A).

Safe geometric design for minicars

Abstract: Because minicars are less safe in both multivehicle and single vehicle collisions, this FHWA sponsored project is designed to identify those types of accidents (and accident related circumstances) where the small vehicles are over represented in either crashes or crash injuries. The analysis involved accident and roadway data from the States of Washington, Texas and North Carolina, and computer simulation runs related to vehicle dynamics. Results include the general finding of increased rollover propensity of these small vehicles in almost all type crashes, with specific problems with roadside shoulder and sideslope design, ditches in rural areas, pavement edgedrop, culverts and catch basins, median barrier faces, rural traffic islands, utility poles, and with head on collisions on curves where the minicar is more often the striking vehicle. Potential treatments were identified for many of these issues, and research plans were prepared (A).

Suspensions and vehicle stability as determined by the Canadian heavy vehicle weights and dimensions study

Abstract: The Canadian weights and dimensions study has examined a number of heavy vehicle suspensions with regard to vehicle stability and control. The contribution of various suspensions to vehicle rollover has been studied using a tilt table similar to the unit developed at ARRB and by dynamic stability and control analysis. In addition, laboratory measurements were made on a number of suspensions defining principle characteristics useful in mathematical modeling of heavy vehicle stability and control. The results of this work will be presented in an effort to address suspension related vehicle rollover and handling issues which will be of interest to regulatory groups (a).

Simulations of rollover tests

Abstract: : The motion of an occupant during a rollover crash is often Violent and complicated. This motion needs to be studied so as to determine how best to protect an occupant during a rollover crash, and the best tool known is computer models which simulate the motion of an occupant. It was the Air Force's Articulated Total Body (ATB) model which was used. The accuracy of the simulations by this model has to be determined through a limited number of rollover crash tests. Five such tests were conducted under this program using a specially designed rollover test device, and the corresponding simulations of the motion of a dummy occupant are presented. The accuracy of the simulations obtained for these five tests with a rollover test device and the similar accuracy for one full-scale crash test conducted earlier on a different testing program provide confidence that an occupant's motion during a rollover crash, whether belted or unbelted, can be satisfactorily simulated by the Air Forces ATB. Computer simulations, Modeling, Biodynamics, Rollover, Crash.

Safe geometric design for minicars. final report

Abstract: Because minicars are less safe in both multivehicle and single vehicle collisions, this project is designed to identify those types of accidents (and accident-related circumstances) where the small vehicles are overrepresented in either crashes or crash injuries. The analysis involved accident and roadway data from the States of Washington, Texas and North Carolina, and computer simulation runs related to vehicle dynamics. Results include the general finding of increased rollover propensity of these small vehicles in almost all types of crashes, with specific problems with roadside shoulder and sideslope design, ditches in rural areas, pavement edgedrop, culverts and catch basins, median barrier faces, rural traffic islands, utility poles, and with head-on collisions on curves where the minicar is more often the striking vehicle. Potential treatments were identified for many of these issues, and research plans were prepared.