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A crash of a medium duty truck led to a study of the failure mechanism of the truck’s steering system. The truck, after being involved in a multi-vehicle vehicle collision, was found with its steering input shaft disconnected from the steering gear. The question arose whether the steering gear failure was a result of the collision, or causative to the collision. An in-depth investigation was conducted into whether forces on the vehicle due to the collision could cause the steering shaft to separate from the steering gear. Additionally, the performance of the steering gear with the adjuster nut progressively backed off was studied to determine the feedback a driver would receive if the steering gear came progressively apart. From the results of these studies, conclusions with regard to the crash causation were reached.

As a result of the development of Event Data Recorders (EDR) and the recent FMVSS regulation 49 CFR 563, today’s automobiles provide a limited subset of electronic data measurements of a vehicle’s state before and during a crash. Prior to this data, the only information available about the vehicle movements before or during a collision had come from physical evidence (e.g. tire marks), witnesses, aftermarket camera systems on vehicles, and ground-based cameras that were monitoring vehicle traffic or used for security surveillance. Today’s vehicles equipped with Advanced Driver Assistance Systems (ADAS) have vehicle-based sensors that measure information about the environment around a vehicle including other vehicles, pedestrians, and fixed wayside objects.

Trailing axles, otherwise known as tag axles, are utilized in many states to allow heavy duty dump trucks and cement trucks to maximize their capacity. The trailing axle is an additional axle mounted on an arm on the rear of the truck that can be raised and lowered. When lowered, the axle extends the overall wheelbase of the vehicle and increases the total number of axles, thereby allowing for additional load to be carried without exceeding load-restriction regulations. There are multiple manufactures of trailing axles that utilize different suspension designs. One design uses an articulating axle that is mounted to the framework that lowers it. In this study, the sensitivity of this design to tire blowout on one of the trailing axle tires is studied. Testing was conducted that involved initiating a sudden air-loss event by creating a hole in the sidewall of the tire. The handling response of the vehicle was documented with on-board instrumentation and on-board and off-board video.

Because the great majority of All-Terrain Vehicles (ATVs) use a solid rear axle for improved off-road mobility, these vehicles typically transition from understeer to oversteer with increased cornering severity in tests customarily used by automobile manufacturers to measure steady-state vehicle handling properties. An oversteer handling response is contrary to the accepted norm for on-road passenger vehicles and, for this reason, has drawn scrutiny from numerous researchers. In this paper, an evaluation of ATV handling is presented in which 10 participants operated an ATV that was configured to have two different steady-state cornering characteristics. One configuration produced an approximately linear understeer response (labeled US) and the other configuration transitioned from understeer to oversteer (labeled US-OS) with increasing lateral acceleration in constant-radius turn tests conducted on a skid pad.

Through testing conducted by multiple facilities, it has been observed that the class of compact two-person vehicles designed exclusively for off-road operation known as Recreational Off-Highway Vehicles (ROVs) exhibit a range of steady-state handling characteristics - including both understeer and understeer transitioning to oversteer as measured in circle-turn tests similar to those set forth in SAEJ266. This handling characteristic is different from on-road passenger cars and light trucks which, under all but heavy loading conditions, exhibit linear range and limit understeer steady-state cornering behavior. Limit understeer is considered desirable for on-road vehicles because it provides a directionally stable and generally predictable control response. In the research presented in this paper, the handling qualities, including controllability, of a ROV which was modified to have different steady-state handling characteristics ranging from understeer to oversteer is examined.

Extensive testing has been conducted to evaluate both the dynamic response of vehicle structures and occupant protection systems in rollover collisions though the use of Anthropomorphic Test Devices (ATDs). Rollover test methods that utilize a fixture to initiate the rollover event include the SAE2114 dolly, inverted drop tests, accelerating vehicle body buck on a decelerating sled, ramp-induced rollovers, and Controlled Rollover Impact System (CRIS) Tests. More recently, programmable steering controllers have been used with sedans, vans, pickup trucks, and SUVs to induce a rollover, primarily for studying the vehicle kinematics for accident reconstruction applications. The goal of this study was to create a prototypical rollover crash test for the study of vehicle dynamics and occupant injury risk where the rollover is initiated by a steering input over realistic terrain without the constraints of previously used test methods.