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Glare from the headlights of following vehicles which is reflected in rearview mirrors can be a significant problem. Glare can cause driver discomfort, it can diminish the driver's ability to see, and it can cause driver fatigue, particularly during prolonged night-time driving common for many professional drivers. Conventional rearview mirrors, such as silvered and chromed mirrors, offer only one reflectivity level. Variable reflectance mirrors, such as those utilizing electrochromic and liquid crystal technology, are capable of multiple reflectance levels. With variable reflectance, the driver can select a high reflectivity level during daytime driving or when reversing into loading docks, and can select a reduced dimmer reflectance level when driving during glaring conditions. This paper briefly reviews the principal technologies available for variable reflectance mirrors and outlines their performance as glare-reducing mirrors.

It is generally accepted that steering axle tire wear rates are considerably higher in turns than in a straight ahead condition. Ackerman correction accounts for the different turning radii of the left and right steering axle tires in a turn but does not take into account slip angle. Slip angle is a significant factor in tire wear. “Optimum Ackerman” does take slip angle into account and should theoretically reduce tire wear. Theory, simulations, and field results are presented.

Presenting a brand new approach to heat exchangers for engines, transmissions, hydraulic systems, etc. This new heat exchanger is made of only two pieces of circular extruded aluminum profiles: Core and shell. No soldering: The core and the shell is assembled by a minimum of automated work. In an oil to water cooling application, the active surface on the oil side of the core is enlarged by fins 0.2 mm thick, 0.3 mm spacing, and 3 mm high. The fins are made in unique production machines and enlarge the active surface area approximately five times compared to a conventional heat exchanger of the same dimensions. The principle utilizes the low pressure drop at laminar flow and avoids the disadvantage of low heat transfer after a certain laminar flow length. The result is approximately three times higher oil heat dissipation, combined with very low oil pressure drop, compared to conventional technique.

Compacted Graphite Iron (CGI) has been recognized for years as a unique material possessing a fortunate combination of properties intermediate between gray iron and ductile iron. This material, for reasons outlined in this paper, is ideal for cylinder blocks, heads and other cast iron components for diesel engines. It makes possible casting weight savings of up to 1/3 and/or increased power output. This paper will outline reasons why this is now possible, whereas it has seldom been applied in volume production heretofore. Physical and mechanical properties of CGI, which provide the opportunity for weight reduction and increased power, are discussed. Currently, most diesel engine cylinder blocks, heads, liners and many other castings are produced from gray iron, which requires relatively heavy sections to provide the strength, stiffness and durability necessary for commercial application.

When truck tires have a deformation such as radial runout, flat spot, and abnormal wear as a result of panic braking, they affect vehicle vibration in the form of displacement input whose spectrum involves higher order terms of tire revolution. While a truck has vibration modes of frame bending as well as pitching and unsprung-mass viberation in the input frequency range, the tire displacement input induces vehicle vibration as a combination of these modes. Results of calculations and experiments of a 4x2 medium-duty truck are analyzed and an example of means for improving ride comfort is described in this paper.

A major co-operative international research program known as DIVINE (Dynamic Interaction between Vehicles and Infrastructure Experiment) has been completed by the Organisation for Economic Cooperation and Development OECD). DIVINE involved seventeen OECD member countries, and included specialists in vehicles, pavements, bridges, road management and transport policy. Inter-linked research projects were carried out in nine countries and the project took almost four years to complete. DIVINE set out to investigate the benefits of “road-friendly” suspensions for reducing pavement wear and to develop better means of assessing vehicle suspensions for road-friendliness. This paper summarises the most important results of DIVINE and presents means of assessing and simulating the road-friendliness of truck suspensions. Dynamic loading depends on the vehicle suspension, and the use of air suspension generally reduces dynamic loading.

A new oval test track will be designed, constructed and operated in a manner that will successfully pull-together representatives from virtually all of the key interests in dealing with the challenging issues of highway pavement and truck durability. With construction scheduled to begin in the Summer of 1998 and completion scheduled for late 1998 or early 1999, the mission and commitment for this venture is to pull-together the people from several state DOTs, respective universities, and, of vital importance, the truck manufacturing industry. Results from these tests, over a period of a few years, will provide answers that not only greatly improve performance of hot mix asphalt pavements in all state DOTs, but also efficiently and productively address issues of durability and wear performance of medium / heavy duty trucks and key components.

An innovative Power Line Carrier (PLC) Communication system for video and digitally signal processed data distribution using the existing DC copper wire is presented. The major contribution consists of a new signal coupler that achieves a stable transmission bandwidth on the DC electrical lines. Several weeks of continuous beta tests achieved video transmission on the trucks +12V wiring (from the back of the truck to the driver's cabinet) and product manufacturing and delivery has started. Benefits include: simplicity of application; ease of implementation; effectiveness with video and data; applicability to all application types; elimination of coax and twisted pair wiring and its maintenance.

Modem power steering systems for heavy trucks are available with a variety of hydraulic valve options. Two of these options, port design and torsion bar spring rate, directly influence vehicle handling characteristics. This study focuses on the effects of steering torque requirements and valve response on steering activity, which contributes directly to driver fatigue. A test was performed measuring steering torque and steering position at highway driving conditions to compare long term steering effort and corrections with different valve options. The findings indicate lowered effort in power steering systems does not increase steering corrections, if accompanied by increased valve responsiveness.

This paper deals with development of disc brake systems for heavy duty trucks introduced in the market after studying the trend of heavy duty truck market. For reduction of vehicle mass, hydraulic systems were adopted for all wheels while at the same time engineering attention was paid to improve brake torque transfer and pad wear. Besides that,improvement of drag torque and shake back encountered while being developed is discussed. Based on market report the current requirement for improvement and also future trend are described.

Exterior durable paint can be applied to thermoplastic sheet via film lamination techniques. The thermoplastic sheet can be, subsequently, vacuum thermoformed into the final part and trimmed. The part is then ready for assembly without the problems of spray painting. Fairings and bumpers have been produced by this method. For injection molded parts, a painted preform can be insert molded providing a painted part ready for assembly. The film laminate provides superior weatherability and fade resistance compared to “weatherable plastics”. It also provides outstanding resistance to gasoline, oils, acids and bases. Solid colors, metallics and graphic patterns can be produced.

A bus shock absorber of double-tube type was tested with rubber bushings installed on a dynamic testing system using electrohydraulic servo principle. The transmitted force and displacement were measured at different frequencies up to 10 Hz. Test results showed the frequency dependency of quite a large hysteresis loop in force vs. velocity diagrams and significant asymmetrical damping in extension and compression. A five-parameter shock absorber model was developed based on a linear valve characteristic assumption. The influence of the rubber bushing was analyzed and considered as a contribution to the effective compressibility of the system. The Gauss-Newton method was utilized to estimate the model parameters by time-domain nonlinear curve fitting. The model was in good agreement with the test data, specially in the extension stage and in the higher frequency range. The estimated parameters were consistent with the physical configuration of the shock absorber.

The CLUTCH WEAR ANALYZING TECHNOLOGY has been developed by Mannesmann Sachs to obtain detailed information of the friction load of clutch facings during vehicle operation. A special challenge was the self-imposed task not to install additional sensors. This became possible by using/reading the CAN (Controller Area Network) bus signals.

Carnegie Mellon Driving Research Center, together with ISIM, is presently involved in the design and development of an Advanced Human Factors Research and Driving Training Research Facility. The facility has been designed to address human factors issues and driver training issues. Human factors interests include developing countermeasures for fatigue and driver/vehicle interface issues. Driver training issues include validating the usefulness of simulators for driver training, developing effective curricula and investigating simulator fidelity needed for effective training. A key component of the facility is the Carnegie Mellon TruckSim that will be capable of simulating a variety of commercial and emergency vehicles using interchangeable cabs mounted to a common motion platform. TruckSim's modular configuration will allow for rapid and cost effective design of experiments and training scenarios. A first research program to evaluate fatigue countermeasures is presented as an example.

The stabilizer bar attachments problem can not be simply analyzed by using linear FEA methodology. The large deformation in the bushing, the elastic-plastic material property in the bushing retainer bracket, and the contact between different parts all add complexity to the problem and result in the need for an analysis method using a non-linear code, such as ABAQUS. The material properties of the bushing were experimentally determined and applied to the CAE model. It was found that using strains to estimate the fatigue life was more accurate and reliable than using stress. Many modeling techniques used in this analysis were able to improve analysis efficiency.

Eleven focus groups were conducted nationwide to gain an understanding, from the local/short haul (L/SH) drivers' perspective, of the general safety concerns related to L/SH trucking and, specifically, the degree to which fatigue plays a role. As part of the discussions, drivers listed and ranked issues that they believed caused them fatigue on the job. The top five fatigue-related issues, ranked in terms of importance, were: (1) Not Enough Sleep, (2) Hard/Physical Workday, (3) Heat/No Air Conditioning, (4) Waiting to Unload, and (5) Irregular Meal Times. Based on the results of these focus groups, it appears that Fatigue is an issue in L/SH, but perhaps not to the extent that it is in long-haul.

To better understand the issues surrounding commercial driver reliance upon in-vehicle sleeper berths for rest, ten focus groups were conducted with long-haul operators. These focus groups were held in eight cities across seven states to provide a geographically diverse sample of long-haul drivers. Issues that were explored included factors affecting the quality and quantity of sleep that drivers receive in sleeper berths, drivers' physical and mental fatigue while on the road, and other related safety issues associated with long-haul truck operations where sleeper berths are used. The results of these focus groups are presented and reflect a wide variety of driver comments, perceptions, suggestions, and recommendations.

This paper discusses the failure mode of a steel driveshaft as it goes into an unstable state as the shaft approaches its critical speed. Two axial buckling theories, Johnson and Euler, will be used to verify the cause of failure for a driveshaft exhibiting the phenomenon of catastrophic failure at its natural bending frequency.

It is common practice for countries to have general access “workhorse” vehicles which are subject to one set of limits and limited access vehicles subject to a different and higher set of limits. The first option for improving productivity is usually a simple combination representing economies of scale using existing trailer units. An alternative to this practice, already being adopted in most countries, is the use of innovative vehicles. As part of nations' size and weight systems, processes for reviewing and changing limits are becoming more selective and are using elements of performance-basing. There is persuasive evidence from a number of countries that current size and weight systems are extremely effective for the simple considerations of vehicle width and height, and for pavement wear. A misplaced emphasis is placed on overall length in some countries and low-speed offtracking is a well-recognized, but very poorly controlled, performance measure.

An oxidation catalyst for diesel engines has been tested in the North American market with proven satisfactory initial performance and durability tests of vehicles but has yet to be evaluated by its bench durability tests due to shorter test duration. Therefore, the oxidation catalyst, durability tested by vehicle and bench, was subjected and the test data were analyzed to clarify its degradation mechanism and set up outlooks for evaluation of its durability by bench tests.