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Tracked vehicles offer many advantages off road in difficult terrain. A primary factor limiting their application, however, has been providing a capable steering system at reasonable cost. This problem has been solved in high speed military tracked vehicles where cost is not the dominant factor. Now a new tracked vehicle steering unit has been developed which provides the same performance as the most advanced military systems, but which is manufactured economically from standard automotive components. This can be matched with standard engines and transmissions to give vehicle performance which formerly could not be obtained at a commercially acceptable price.

The transition from ICE to electric power trains in new vehicles along with the application of advanced active and passive noise reduction solutions has intensified the perception of noise sources not directly linked to the propulsion system. This includes road noise as amplified by the tire cavity resonance. This resonance mainly depends on tire geometry, air temperature inside the tire and vehicle speed and is increasingly audible for larger wheels and heavier vehicles, as they are typical for current electrical SUV designs. Active technologies can be applied to significantly reduce narrow band tire cavity noise with low costs and minimal weight increase. Like ANC systems for ICE powertrains, they make use of the audio system in the vehicle. In this paper, a novel low-cost system for road induced tire cavity noise control (RTNC) is presented that reduces the tire cavity resonance noise inside a car cabin.

A lumped-parameter thermal network model, based on the analogy between heat transfer and electric current flow, is presented for hybrid powertrain cooling systems. In order to optimally select the powertrain components that are commercially viable and meet performance, emission, fuel economy and life targets, it is necessary to consider the influence of cooling architecture. Especially in electric and hybrid vehicles, temperature monitoring is important to increase power and torque utilization while preventing thermal damages. Detailed thermal models such as FEA and CFD are considered for component level assessments as they can locate thermal hotspots and identify possible design changes needed. However, for the system level analysis, the detailed numerical models are not suitable due to the requirement of high computation effort.

This paper presents some of the history of the Spacemetal process development; a discussion of the core forming machine, a description of the welder where corrugated core and facing sheets are joined; the quality control process employed for inspecting the finished product; and some of the material properties and applications. FOREWORD Development of a production process and the machines for fabrication of a resistance welded steel sandwich was made by Missile Division, North American Aviation, Inc. Development was carried forward under contract AF 33(600)-26154 from the Manufacturing Methods Branch, Industrial Resources Division of the Air Materiel Command USAF.

METHOD of selecting sbaetiasfraicntogrsy for the transmissions and final drives of pneumatic-tired tractors that depends on a knowledge of average operating conditions is reported by John Borland. The well-known method of rating bearings on a fatigue basis is, according to tests carried out by Mr. Borland, a reasonably accurate way of predicting bearing life when loading conditions are definitely established. However, the tables that have been compiled by the bearing manufacturers are satisfactory for determining bearing life only of bearings subjected to a constant load at a constant speed. Since tractor transmissions are subjected to as many different loading conditions as there are speed changes provided in the tractor, tractor transmission bearings cannot be selected directly from these tables. They must be used in conjunction with the formula for determining a factor called weighted life.

A machine was built to study non-rolling tire stiffness and damping coefficient of agricultural tractor tires in the vertical direction. Measurements of static deflection and contact area on a rigid surface can be performed. During dynamic experiments, a sinusoidal deflection function is imposed to the test tire to determine dynamic stiffness and damping coefficient. The experimental setup and methodology are described in this paper. A complete sample test and its analysis are also presented. This paper was approved for publication by the Director of the Louisiana Agricultural Experiment Station as publication number 93-07-7238. Trade names are used solely to provide specific information. Mention of a trade name does not constitute a warranty of the product by the Louisiana Agricultural Experiment Station of the LSU Agricultural Center nor an endorsement to the exclusion of other products not mentioned. The authors are François P. Brassart, Graduate Research Assistant, and Malcolm E.

The type of mobile equipment needed by utility companies in the performance of their services to the public are many and varied. The application is often so unique that it taxes the ability of a chassis which was basically designed as a highway carrier. Although these machines are common equipment in the utility business, they are unusual equipment in the motor truck business, and must be purchased with meticulous care and applied with good engineering knowledge and foresight. The end product is a machine designed by three engineers who never meet, the chassis engineer, the equipment engineer, and the engineer in charge of equipment at the utility company. The paper is prepared in dialogue form to characterize the brief exchange of information, to provide thought on vehicle selection, and to examine some of the problems usually encountered by motor truck and utility companies.

A method to achieve roll-off cleanliness has been in existence since November 1979. This paper reviews the application of the procedure in one manufacturers operation and establishes additional considerations which should be given. A method of statistical analysis of shipaway cleanliness is employed to demonstrate capability.

The traditional approach to materials selection is to compare the results of direct substitution of alternative materials on an individual part-by-part basis. The engineer then frequently faces so many design constraints that use of a new material is infeasible. This approach also precludes redesign to optimize the characteristics of new materials. A methodology is presented which facilitates the consideration of a large system comprised of many components. The management science technique of “multi-attribute utility analysis” is applied as a tool for use by automotive design engineers. Attributes include capital cost, piece cost, weight, design flexibility and corrosion resistance. The results serve as a decision making tool to determine which design provides the greatest overall value. Also, the results may be used as a design aid to quantify desirable tradeoffs between attributes, thus pointing the way towards optimal redesign.

The goal of this study was to determine the design constraints for the Georgia Southern SAE BAJA vehicle to operate in a rough terrain without unwanted direct body impact. The BAJA vehicle may encounter two distinct kinds of failure while climbing or descending terrain obstacles: Hang up failure, and Nose in failure. Hang up failure occurs when the bottom of the chassis of the vehicle makes contact with the obstacle. This occurs after the front tires have cleared the obstacle but before the rear tires have. This mitigates the pace of the vehicle but does not structurally threaten it. Nose in failure is when the protruding front bumper or “nose” of the vehicle makes contact with either the ground or the obstacle before or after encountering the obstacle. The possible ramifications of this event are much more disastrous than the Hang up failure. Nose in failure can send the vehicle into an end over end flip, or cause significant structural damage to the frame.

A simplified mathematical model of tandem suspension is presented to study the different parameters of tandem suspension. The equations of motion are compiled considering the system to be 3 degrees of freedom system, taking into accounts both oscillation and deflection of the leaf spring. The response characteristics for vibration isolation for the company test track road profiles at different speeds of the vehicle are calculated. The sensitivity of acceleration to variations in un-sprung masses and axle spacing is illustrated. Further, the usefulness of the model for studying the effect of shock absorber positioning on ride of tandem bogie suspension system is demonstrated.

By using a radio frequency (RF) audio distortion measurement test setup, communication devices can be evaluated for degradation caused by electromagnetic interference (EMI) from active vehicle components. This measurement technique can be used to determine the performance of a radio receiver under a variety of conditions. The test setup consists of making measurements on a baseband audio signal that is sent to the device under test (receiver) via over-the-air RF transmissions. Once a baseline is established, active components on the vehicle can be powered on to determine their contribution to the receiver's degradation. The degradation measured is a result of distortion caused by conducted, radiated, and/or coupled EMI from active components into the receiver's passband.

Biofuel can enable a sustainable transport solution and lower greenhouse gas emissions compared to standard fuels. This study focuses on biodiesel, implemented in the easiest way as drop in fuel. When mixing biodiesel into diesel one can run into problems with solubility causing contaminants precipitating out as insolubilities. These insolubilities, also called soft particles, can cause problems such as internal injector deposits and nozzle fouling. One way to overcome the problem of soft particles is by filtration. It is thus of great interest to be able to quantify fuel filters’ ability to intercept soft particles. The aim of this study is to test different fuel filters for heavy-duty engines and their ability to filter out synthetic soft particles. A custom-built fuel filter rig is presented, together with some of its general design requirements. For evaluation of the efficiency of the filters, fuel samples were taken before and after the filters.

This paper describes the design strategy adopted for developing a new high performance actuation system referred to as the ElectroHydraulic Actuator (EHA). The design approach can be divided into fives phases that include: pre-conceptual analysis, conceptual design, preliminary design, detailed design and, integration and test. An important aspect of the design process is the use of modeling and simulation for the analysis, sizing and selection of off-the-shelf parts, and for the detailed design of new custom made components. EHA is based on hydrostatic transmission. It is a unique device with its own characteristics and requires hydraulic components that are specifically tailored to its needs. A prototype of EHA has been produced and has demonstrated an extremely high level of performance. The performance of this prototype complies with design requirements and validates the chosen design approach.

Today, active dynamic control systems for commercial vehicles, offering improved safety, are frequently discussed. Yaw stabilising systems are based on theories from passenger car implementation, yet roll stabilisation - probably introduced in the near future - requires increased knowledge of rollover mechanics. Static analysis, providing steady state rollover threshold (SSRT), is the most common approach. Nevertheless in a rolling vehicle, kinetic energy is always present, deteriorating roll stability, invalidating the analysis. A simple method determining the dynamic rollover threshold (DRT) is therefore introduces in this paper. DRT is the worst case measure of roll instability: the conditions are necessary but not sufficient for rollover.

A method for the analysis of a damaged bearing is described. An emphasis is placed on obtaining complete and accurate application information; conducting a thorough visual examination; making physical measurements as necessary; and conducting metallurgical tests. The method has been used for tapered roller bearings as well as a variety of other components of various steel types and processing histories.

Driver visibility from commercial vehicles is often an issue in post-accident litigation. While the visibility through the windows of most vehicles is restricted due to the required structure of the vehicle itself, most manufacturers and users incorporate a series of mirrors to enhance driver visibility and to reduce blind spots. The challenge for an engineer is to first demonstrate what the driver could see to a reasonable degree of engineering certainty, and then to convey this information in a form that is easy for the lay person to grasp. This paper outlines procedures for calculating and modeling the driver visibility from commercial vehicles. The primary techniques presented require access to the vehicle, although the paper also presents techniques by which visibility can be analyzed through photogrammetry and 3-D computer models, both for the vehicle and for any mirrors incorporated onto the vehicle.

A coalescing filter is typically used in a compressed air system to remove liquid and oil aerosols. A coalescing filter is most efficient when located downstream of an air dryer. The air dryer removes most of the liquid oil condensed in the compressor discharge line. Measuring the percent of oil removed by a coalescing filter is useful for determining efficiency. This paper covers a laboratory method to reproduce oil aerosols much like the filter will see in an actual application. High duty cycles produce the maximum amount of oil from the compressor. The air dryer acts as pre-filter for the coalescing filter. The coalescing filter element and its associated housing should be tested as a unit since the element's inherent efficiency is effected by the design of the housing.

In contrast to passenger cars, commercial vehicles exist in many layouts for different customer applications. The Daimler AG provides with their Mercedes Benz Trucks a product portfolio of 6 commercial vehicles (Econic, Atego, Axor, Actros, Zetros, Unimog), which are available in a multiplicity of model variants. Therefore, the well-known driving cycles of passenger cars such as NEDC (Europe), the 10-15 mode (Japan), the FTP & FTP75 (USA) and others cannot be used in regard to fuel consumption or dimensioning of a commercial vehicle [1, 6, 15]. A diversification of type and usage of the commercial vehicles is obligatory necessary, as already shown in publications of Holloh et al. [10] However, this paper offers a method which uses collected data from customers, in order to develop objective reference cycles or test cases. This described method can be equally used for both, creating the reference cycles of commercial vehicles mentioned above, as well as passenger cars.

In recent years research and development on ‘compatibility’ in the area of collision safety has been proceeding. It is a big issue how to prevent an increase in the severity of injuries of occupants in a weaker vehicle. With regard to FUP (Front Underrun Protector), we consider it possible to further lessen the severity of injuries of car occupants by simultaneously studying the requirement for collision safety on the passenger car as well as the requirement for strength stipulated by the ECE regulation. Therefore we develop the study method for collision safety structure using an optimizing method.