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Often, commercial considerations surrounding the development of new electronics designs are given less importance than design-based issues. Tooling ownership agreements for instance, can scuttle a program as rapidly as the inability to meet geometric requirements. Several commercial issues must be addressed to help ensure a timely conclusion to the new products development program.

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.

A new method of analysis for the dynamic response of layered pavements to moving dynamic loads has been developed. The method accounts for wave propagation as well as inertia and damping effects. The loads are modeled as a series of moving haversine pulses. The proposed method can handle any load configuration, thus making it possible to model multiple wheel configurations of trucks, buses and airplanes. Vehicle speed was found to have a significant effect on pavement response, while loading frequency proved to have only a minor effect. Excellent agreement with field results from full-scale pavement tests was achieved.

A yaw/roll simulation model is developed to assess the dynamic performance of 5, 6, 7, and 8-axle logging truck configurations in this paper. Results predicted by the yaw/roll models for a 5-axle tractor/pole trailer (with outriggers) and a 6-axle tractor/jeep/pole trailer (with outriggers) are compared with those measured in field tests for purposes of model validation. Good agreement between the simulations and measurements has been obtained. Certain performance measures for the tested tractor/pole trailer and tractor/jeep/pole trailer, such as Rearward Amplification Ratio, Load Transfer Ratio, Transient High-speed Offtracking, Understeer Coefficient, Static Rollover Threshold, and Low-speed Friction Demand, are examined by using the yaw/roll models.

The use of dampers (shock absorbers) in heavy truck suspensions is central to reducing dynamic wheel loads. Dynamic wheel loads are responsible for a significant component of vehicle related road damage. Improving the viscous damping characteristics of suspensions will substantially reduce dynamic wheel loads thereby enhancing suspension “road-friendliness”. Because dampers deteriorate over time, a new test is required to determine the in-service condition of dampers. There is a need to develop improved dampers that are optimized to reduce dynamic wheel loads while providing good ride quality. They must be sufficiently robust to dissipate the required energy from various magnitudes of road unevenness over extended life cycles.

The longitudinal load transfer encountered in a partly-filled ellipsoidal tank truck, subject to a straight-line braking maneuver, is investigated as a function of the location of partition walls, deceleration and the fill level. The response characteristics of the truck equipped with a compartmented tank are evaluated in terms of dynamic load transfer, stopping distance, braking time and time lag between the front and rear axle wheel lock-up. The braking response characteristics are derived as a function of the load shift, and number and location of partition walls. Road tests were performed on an airport fuel truck, equipped with a 3 m long tank with two movable partition walls. The simulation results derived from the test vehicle model are compared to the road test data to demonstrate the validity of the analytical model. The results show good correlation with the measured data acquired under straight-line braking maneuvers performed under different fill levels and initial speeds.

A dynamic stability analysis model of a five-axle tractor semitrailer vehicle is developed using the MATLAB/SIMULINK application tool. The linearized vehicle model is utilized to investigate the impending instability limits under various design, and operating conditions. Computer simulations are performed for step steer and a typical highway maneuver as input conditions to generate the yaw response characteristics. The model development is accomplished in a modular form to accommodate interactive re-runs of the model with design variations. SIMULINK modeling provides greater flexibility in development and incorporation of active control system modules in the model in order to investigate possible enhancement of vehicle stability limits.

Buses used in inter- and intra-city applications are characterized by large windshields. These are usually higher than their width and, in most instances, are divided with a center molding. The configuration lends itself to a pantograph wipe pattern to allow cleaning of the largest area possible. Wiper operation is demanding due to real estate constraints, that is, limited area for the motor and its linkage. FEATURES OF OPERATION have been lacking due to complication of the pneumatic system, confusion due to multiple controls, and the ever-present need to contain price. ECAM (Electronically Controlled Air Motor) has introduced the electronic control of the windshield wipers while combining, for operator safety and convenience, operation in alternative modes, smooth stroke, added features, and greater available power. Improvements in operational features such as INTERMITTENT or interval wiping, PROGRAMMED WASH, and headlight activation are featured with ECAM.

One of the major goals in the design of the new Ford Aeromax and Louisville heavy truck product line was to achieve competitive leadership in visibility. Market research found that visibility was an important issue to the heavy truck driver. Visibility is defined as both direct and indirect (i.e., the driver's ability to see with and without the use of supplemental vision devices such as mirrors) and both interior and exterior. The scope of this paper includes the work which was accomplished in evaluating direct and indirect exterior visibility and the resulting vehicle design which achieved Ford's leadership goals. Poor weather visibility and interior vision are beyond the scope of this paper. Polar Plots were the method of choice in the Aeromax/Louisville visibility studies. Industry acceptance of these techniques has been established in the recent approval of SAE J1750, “Evaluating the Truck Driver's Viewing Environment”.

This paper describes the assessment of driver interfaces of a type of electronics-based collision avoidance systems that has been recently developed to assist drivers of vehicles in avoiding certain types of collisions. The electronics-based crash avoidance systems studied were those which detect the presence of objects located on the left and/or right sides of the vehicle, called Side Collision Avoidance Systems, or SCAS. As many SCAS as could be obtained, including several pre-production prototypes, were acquired and tested. The testing focused on measuring sensor performance and assessing the qualities of the driver interfaces. This paper presents only the results of the driver interface assessments. The sensor performance data are presented in the NHTSA report “Development of Performance Specifications for Collision Avoidance Systems for Lane Changing, Merging, and Backing - Task 3 - Test of Existing Hardware Systems” [1].

Sustainable development and product life cycle design are rapidly becoming important elements in a company's environmental management program. The primary purpose of this paper is to review the background of these concepts and show how Navistar is approaching their implementation. Topics discussed include the definition and background of sustainable development, industry's role relative to implementing sustainable development, ecosystems and importance of maintaining ecosystems, industrial ecology and ecosystems, International Chamber of Commerce (ICC) environmental principles, product life cycle design and pollution prevention. Key to Navistar's implementation of sustainable development is the utilization of product life cycle design approaches and pollution prevention practices.

The objective of the American Automobile Manufacturers Association (AAMA) Heavy Truck Brake Tire Test was to evaluate how different tires might effect a vehicle's performance when tested per the Society of Automotive Engineers, Inc. (SAE) J1626 “Braking, Stability, and Control Performance Test Procedures for Air-Brake-Equipped Truck Tractors.” During the summer of 1991, the Motor Vehicle Manufacturer's Association (MVMA), now known as the American Automobile Manufacturer's Association (AAMA), contracted Transportation Research Center Inc. (TRC) to perform a Heavy Truck Round Robin Brake Test to evaluate the practicality and repeatability of the ABS test procedure developed for the Motor Vehicle Safety Research Advisory Committee of NHTSA (SAE Paper 922484). One of the conclusions derived from that test program was that tires seem to play a more significant role than expected in vehicle braking performance.

The Clean Air Act Amendments of 1990 have brought about wholesale changes in the mandated requirements for the EPA and states to bring clean air to the country. Of particular interest to the light and heavy duty truck and bus industry are the requirements for VOC reductions in Title I, the hazardous pollutant reductions requirements in Title III, and the new permitting scheme required under Title V of the Act. The inter-relationship of lower VOC coatings, hazardous pollutant reduction, and permitting requirements will be presented. Since the Act does not fully mesh these requirements, the pathways that coating suppliers and coating application facilities can use to come into compliance will be explored. Specific VOC content of conforming coatings will be presented, how they will impact application processes, and how hazardous air pollutant reductions can be achieved is explored.

Fluid mountings have become a common means of supplying damping in vibrating systems at a fairly specific frequency, amplitude and direction across the mount. They have been successfully applied in the automotive and truck industries as engine and cab suspension components. A less complex type of mounting/damper is described, drawing on the hysteresis/frictional properties of elastomers, to provide multiple axis damping properties porportional to input amplitude and that are frequency insensitive when compared to hydraulic mount designs. Although based on an old concept of multiple indenters sliding along an elastomeric layer, recent materials improvements have allowed a robust and versatile mounting/damper design to be developed and applied.

This paper reports a numerical simulation method for suppressing abnormal vibration on the cab caused by torsional vibration on the powertrain, using a mechanical dynamics analysis software. The simulation model for the numerical analysis is adopted to the powertrain. Seven design parameters were selected and optimized to minimize the acceleration of the vibration by using Design of Experiment (DOE). Validation tests were conducted on the optimized model, and a good agreement was achieved between the test results and the calculated ones. This new design has helped us a lot to save weight, cost and time by narrowing down design change proposals.

For Sports-Utility, Off-Road and Light Truck application, a new, permanent 4x4„double offset” type of Transfer Case is under development by SFT, which extends the state of the art by introducing an extremely compact, modular combination of proven elements to form a unit which can meet the requirements of different, modern 4x4 system configurations. The specific arrangement of components results in reduced cost and weight, lower noise, and high manufacturing flexibility for a number of options, such as fully synchronized High-Low shift, motorized High-Low shift, mechanical or VC differential lock, front axle shut-off, additional power take-off, and transmission brake. The first unit is designed for a maximum input torque of 1250 Nm and, according to market requirements, can be supplemented with units of different torque capacity to form a new generation of Transfer Cases.

Environmental and economic factors are contributing to a growing market for vehicular engines fueled by natural gas. Engine users are moving from general curiosity in alternative fuels and their low emissions potential to demanding Original Equipment Manufacturers to provide such engines that meet their operational requirements. Customer needs of performance, reliability and durability from natural gas engines are requiring the engine manufacturers to develop appropriate technologies to achieve these objectives. This paper describes some of the technologies developed at Cummins Engine Company for the B5.9G natural gas engine. The lean burn concept developed for the engine and its advantages are described in addition to the techniques utilized to implement the technology for vehicular applications.

Diesel emission control is being addressed worldwide to help preserve the global environment. In 1994, emission controls in the U.S. called for reduction of diesel particulate matter (PM) to 10 to 20% of 1986's initial limit. In the same year, we developed and marketed small and medium duty trucks which were equipped with PM reduction systems that oxidize soluble organic fraction (SOF) contained in the PM, in order to satisfy these new regulations. Prior to their marketing, a catalyst was selected from among several types of candidate catalysts. Durability tests were performed using a catalytic converter-equipped small duty truck to verify the durability of the chosen catalyst. The durability test course was set up combining urban areas and expressways in the southern part of California, U.S.A.. The cumulative total distance covered on the test course reached 200,000 km. During the durability test, the catalyst was evaluated by measurement of PM emission using a chassis dynamometer.

Heavy-duty diesel engines for transit bus applications are having to meet increasingly stringent emission standards. The new engines are significantly cleaner than they were just a few years ago. However, due to the long life of transit buses in Ontario (18 years), many buses still in service are powered by older engines which produce greater amounts of regulated exhaust emissions. The Ottawa-Carleton Regional Transit Commission (OC Transpo) has an interest in reducing emissions from older transit buses in their fleet. Eight Donaldson particulate trap systems were installed on transit buses. The purpose of the work, involving four different bus/engine combinations, was to assess the practicality and benefits of particulate traps in transit applications. This paper discusses the demonstration of diesel exhaust particulate traps in Ottawa-based transit buses.

A heavy-duty engine testing project involving Cummins Engine Company, Southwest Research Institute (SwRI), and West Virginia University (WVU) has been completed. This project evaluated the transient exhaust gas emissions rate of Cummins N-14 heavy-duty diesel engines converted to natural gas. Three heavy-duty N-14 diesel engines were converted to run on natural gas using a lean burn strategy by SwRI and are in field service in Santa Barbara Air Pollution Control District (SBAPCD). Two of the engines were tested under a steady-state cycle that simulates the U.S. heavy-duty transient cycle. The third engine was tested at the WVU Engine Research Laboratory following the U.S. Federal Test Procedure (FTP). However, at WVU, lean burn combustion strategy was shifted rich of stoichiometric during idling time of the FTP test. This may have caused the engine to produce more total hydrocarbons (THC) and carbon monoxide (CO).