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Producing a commercial vehicle in a single location to satisfy the needs of multiple applications in a world market, cannot be realistically accomplished. Instead, Mercedes-Benz and its subsidiary, Freightliner Corporation, have adopted a strategy, characterized as multi-domestic rather than multinational, which relies on production of trucks in many locations. In this way, qualities can be offered which are in unique demand in those markets while minimizing the development effort and capitalizing on worldwide component sourcing. Presently Mercedes-Benz, including Freightliner, operates 54 truck manufacturing and assembly plants throughout the world. As a part of, and following this strategy, Freightliner has recently launched an all new medium-duty truck program for the U.S. market, produced in an all new manufacturing plant in Cleveland, North Carolina. The present paper describes this program and its development. Refer to Fig. 1.

High tech is permeating the trucking industry, which is now entering the electronics and information age. The trucks of today are becoming increasingly sophisticated with technical innovations occurring in many areas. Electronic engines, electronic service tools, onboard computers, real time communication utilities and computerized operations represent a few key technical solutions that are finding increasing penetration in the market. These technical solutions complement and/or compete with one another as they strive to meet the needs of the trucking fleets. The extent to which they complement and/or compete with one another is not readily or widely understood. It will take skill and knowledge on the part of the customer and the supplier to know the difference. A quick glance at these solutions makes one simple fact clear: electronics is the technology that is common to all these solutions and is capable of weaving them together.

An electronic accelerator pedal has been designed for use on heavy trucks with on-board electronics requiring accelerator position input. The one-piece assembly is a floor mounted treadle design with all required electronics and wiring protected behind the instrument panel. The assembly also has been designed to operate, or be operated by, mechanical devices outside of the cab. It is these features, and others, which allow this assembly to satisfy the concerns and needs of all activities which must interface with the accelerator system.

This paper outlines the extension of the “GAPFRIC” concept to model in three dimensions the frictional interface between brake linings and drum of an S-cam operated pivoted abutment type of leading and trailing shoe brake assembly. The approach incorporates an accurate representation of the brake itself to include such features as drum stiffness and its mounting face. The brake shoe representations include the actual web and platform thus eliminating the need for shoe stiffness approximations to a curved beam of uniform section as used in previous 2D work. Analyses have been completed to investigate how the combined axial and circumferential distortions, within a brake, influence the temperature and interfacial pressure distributions and consequent brake performance. Consideration is given to the significance of shoe and drum stiffness and the effects of different lining moduli are illustrated.

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.

The technologies of fatigue life estimation and modal analysis are typically applied independently in current ground vehicle development practice. Here, an analysis technique is demonstrated that integrates these technologies and reflects the relationship between fatigue damage and structural modes. The results may be used to identify the most damaging modes within a complex structure and to estimate the additional life that can be gained by eliminating or modifying these modes. This technique has been used to successfully enhance the structural integrity of a Class 8 truck hood assembly.

To evaluate and refine interior architecture of the new Dodge Ram pickup truck three years before production, a road worthy interior package validation buck was built using a fiberglass body shell. Molds for the shell were made using CAD/CAM techniques. Advanced CAD/CAM techniques were used to build the interior buck of a subsequent model from individual panels molded in carbon fiber. This buck also included inner structural panels and interior trim components taken from CAD data. For this and subsequent new vehicle programs, refinement of construction techniques allows the bucks to serve as aids in product design and manufacturing feasibility studies.

The current practice for programming electronic control modules using SAE Recommended Practice J1708 permits each vendor to provide a unique hardware and software interface for his products. A standardized communications interface for J1708 communications at OEM Assembly Plants is needed to eliminate the impacts of the unique interfaces. Draft SAE Recommend Practice J2214, Vehicle Electronic Programming Stations [VEPS] System Specification for Programming J1708-capable components at OEM Assembly Plants is proposed to address these concerns and improve upon the file-based interface documented in SAE Information Report J1924, OEM/Vendor Interface Specification for Vehicle Electronic Programming Stations. J2214 references the proposed SAE Recommended Practice J1683, MS-DOS™ Interface for J1708 Communications to define the standard interface.

Chrysler Corporation's Jeep and Truck platform implemented a new design and prototype process for the body-in -white of a new pickup truck. A team approach achieved concurrent body design, stamping die design, assembly process development, and assembly tooling development. The first domestic US industry use of a 100% electronic design and release system was instrumental in the process. The new process produced a prototype body-in-white on time at 95 WBVP (weeks before volume production) with the highest level of production-intent components ever achieved within Chrysler at this stage of development.

Instrumentation gauges must satisfy the needs of the customer. Sophistication in heavy duty trucks continues to evolve at a very fast pace. Variation in customer features for instrumentation increases year by year. However, intense competition between truck manufacturers do not allow for vehicle cost increases. Therefore, instrument gauge packages must be designed to be flexible to meet a wide variety of customer needs at the lowest total cost. Instrument gauge customizing and testing in the assembly plant can be simplified with computer assistance. Built-in diagnostic self testing gives the driver confidence that the gauges are operational. Performing all of these tasks must be accomplished using a programmable cluster that displays information in a traditional manner yet has many more capabilities than previous gauge designs.

A new method to predict brake squeal occurrence was developed by MSC under contract to Ford Motor Company. The results indicate that the stability characteristics of this disc brake assembly are governed mainly by the frictional properties between the pads and rotor. The stability is achieved when the friction coefficient of the pads is decreasing as the contact force increases. Based on the results, a stable brake system can be obtained without changing the brake structure by incorporating the appropriate frictional coefficient in the brake system. The method developed here can be also used as a tool to test the quality of any brake design in the early design stage.

A new bumper system which provides 8 kph (5 mph) vehicle protection with superior quality, outstanding durability and high value is in production. The system includes five new technologies: Hot stamped, ultra high strength front beam, 970 N/mm2 (160 KSI) which also is the #1 body structure crossmember. Ultra high strength roll formed rear beam 1150 N/mm2 (190 KSI). polypropylene foam isolators designed for controlled energy management Thermoplastic olefin (TPO), injection molded fascias Two component urethane paint for long term color, gloss and scratch resistance. This bumper system, installed on over 100,000 vehicles so far, meets both MPV and passenger car 8 kph standards. Consumer and insurance industry trends indicate increasing demand for Multi Purpose Vehicle (MPV) bumper systems which meet 8 kph criteria. The major competitors in the MPV market (Aerostar, Grand Caravan, Toyota Previa, GM APV's, and Mazda MPV) have either 0 kph or at best 4 kph systems.

Air disc brakes have been under development in Europe now for many years, and have reached the stage where the technical demands of energy capacity, disc and pad life, and general durability are being met. The focus of development in European brakes has now moved more towards the cost of installation and ease of assembly and service, as the technology matures. Achieving reduced costs, while maintaining the technical capability of the product, has led to the use of new methods of integration of design and industrial engineering such as “Design for Assembly” and Quality Function Deployment, which in turn have demanded changes in organisation. This paper discusses the application of these new techniques, and highlights the benefits of their usage.

Developments in axle nut configurations now make it possible to position wheel assemblies on the axle spindles of heavy duty combination tractor/trailer vehicles using new installation procedures to assure ideal adjustment of the tapered roller bearings. The ability of all mechanics to accurately control the assembly of wheel end components will be enhanced with axle nut designs conceived in the last two years. Of great significance in this area of interest are pronouncements by tapered roller bearing engineers who now advocate that longer life will be realized for all wheel end components if a limited amount of tapered roller bearing “preload” is introduced and maintained with a mean of finite axle nut adjustment. Until recently, there appeared to be reluctance on the part of the tapered roller bearing manufacturers to advocate improvement of tapered roller bearing service life with application of preload pressure.

Motor vehicles, particularly commercial trucks and buses are using an increasing number of electronic sub-assemblies. These modules contain circuit boards with 6 - 8 layers of interconnected circuitry and require the assembly of 400 parts. The manufacturing process can involve 22 separate processes including automatic assembly high volume soldering, robotics, coatings and automatic test. These processes can cause costs to rise dramatically if functional or vehicle interface requirements are changed late in the design process.

Customers complain about transmission noise in trucks and buses. This paper describes how noise testing can deal with topics such as; Has the transmission been manufactured correctly? - Noise measurements on test stands are an assembly or manufacturing fault diagnostic tool, Will the customer be satisfied? - Using noise measurements on test stands to define the customer's aspirations of acceptable transmission noise, Defining end-of-line noise tests in a way which mimics the customer's subjective evaluation of noise in vehicles and hence providing a reliable Pass/Fail tool, Compliance with legislation. - Diagnosis of the contributions of transmission noise to vehicle pass-by noise. Practical test results illustrate these topics.

A Transfer Matrix Method (TMM) based procedure has been developed to model and predict the resonant frequency of one piece driveshaft assemblies. The TMM approach was selected because it allowed the ability to change the geometry of a driveshaft between joint centers. This ability more accurately models some driveshaft types, specifically an inboard slip assembly. When an inboard slip assembly was modeled using the TMM, the TMM prediction was within 6.7% of the actual test results compared to 16.1% using the SAE AE7 prediction with a typical correction factor.

In recent years, several transit agencies have tested buses equipped with hybrid powertrain systems. It has been reported that hybrid powertrains have significant advantages over conventional diesel engine systems, in the area of emissions and fuel economy performance. Presented in this paper are engineering issues and suggestions from an auto component supplier point of view in the design of such a powertrain system. The particular system being considered consists of a downsized diesel engine, a generator, a battery package, two identical AC induction motors, and gearbox systems for the left and right driven wheels. The assembly is supported by an H-shaped suspension sub-structure uniquely designed to achieve the “ultra-low floor” configuration. Our discussion covers the system performance, as well as the durability issues. In particular, the presentation focuses on the durability and the design layout of the gearbox and suspension substructure.

The transporting of live cattle involves the use of Class 8 tractors and livestock semi-trailers for transportation from farms and feedlots to processing plants. This travel may include unimproved roads, local streets, two lane highways, as well as interstate highways. Typically, cattle are compartmentalized in a “double deck” fashion as it provides utility and comports with size and weight limits for commercial Class 8 vehicles. Concern has been expressed for the effect of cattle movement upon the dynamic performance of the loaded Class 8 tractor-livestock trailer assembly. Loading guidelines exist for cattle that attempt to prevent injury or debilitation during transit, and literature exists on the orientation and some kinematics of loaded cattle. Considerable literature exists on the effect of liquid slosh in tankers and swinging beef carcasses suspended from hooks in refrigerated van trailers on the dynamic response and roll stability of those vehicles.