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The Pennsylvania Transportation Institute (PTI) operates the Bus Testing and Research Center for the Federal Transit Administration (FTA). The objective of this paper is to present a summary of important findings during the first eight years of Center operation. This paper presents an overview of the test procedures and a descriptive matrix of vehicles submitted for testing. A summary of test results is provided, which includes a distribution of failures classified by severity and subsystem type. The paper briefly describes the developmental status of including brake performance and emissions testing as well as future plans for the implementation of electric and hybrid-electric bus testing.

The handling and ride comfort characteristics of a medium bus during a single lane change manoeuvre and bump pass are investigated in terms of the change of the center of gravity, stiffnesses of springs, and damping coefficients through computer simulation using DADS. Dynamic full model of the vehicle is established using tires, dampers, leaf springs, sprung mass, and unsprung masses. A driver is assumed to steer the vehicle along a prescribed path which was obtained from field tests. He was modeled as a PID controller in the simulation. In order to confirm the validity of the model, simulation results are compared with those obtained from field test. The handling and ride comfort characteristics of the vehicle are compared with root mean square values.

As competitive pressures in the automotive industry continue to increase the need for reduction in product development time, OEM's are searching for ways to eliminate non-valued added activities. Today, still too much time is devoted to the laborious process of manipulation of CAD geometry in the advanced stages of a program in order to develop feasibility for emerging design themes, involving the packaging and function of vehicle systems. Technology is being developed that will eliminate much of the tedium currently involved in this design engineering process. As theme iterations or packaging changes occur, CAD models that intelligently link the theme, the packaging, and the engineering “rules” will automatically “morph” into new designs. This Morphing process will execute CAD model changes according to engineering rules that are considered to be industry best practices.

This paper will introduce the concept of Concept and Concurrent Analysis and Optimization (CCAp for short), and discuss its merits and challenges for its successful application, from a technical perspective. Increasingly strong emphasis have been placed upon integrating analysis and optimization into a product design and development process (PD&D for short) for shorter time-to-market, lower cost, and increased quality and reliability. However, its effect and influence are ultimately limited in scope and extent to downstream from its entry into the process. CCAp promotes early introduction (at and before concept) and continued application (concurrent) along design evolution paths in a process. Concepts, which exist at all levels and on all scales throughout an entire process, are when design changes and variations are the easiest and least expensive to make, and when optimizations are the least constrained and the most effective.

The increase in automotive systems complexity coupled with the requirements to meet tight development schedules and costs, have pushed development teams to find new ways of delivering their product on time. Over the past few years, simulation has become a powerful approach for compressing product development cycles. However, systems are defined using components from different engineering domains such as control system design, mechanical design, hydraulic design, circuit design or software design. Each of these components generally requires different simulation tools. Using these tools each development team independently designs and simulates their specific component. While the current simulation approaches are appropriate for component design, system simulations are harder to execute and maintain. This paper presents a new architecture for co-simulation using distributed object referred as CUDOs. An implementation of the architecture is used to provide a cosimulation example.

A new, enclosed brushless alternator is developed for use in either hazardous or contaminated environments which can produce 50 Amps at 28 Volts DC. The fully enclosed design of this alternator allows it to work in environments which contain corrosive agents, metallic particulates, or volatile media. The brushless design of this unit in conjunction with the enclosure makes this alternator virtually maintenance free.

Allison Transmission and Castrol Industrial North America have teamed up to offer a new synthetic automatic transmission fluid specially formulated for heavy duty automatic transmissions. The new product is called TRANSYND™1 and is approved for use in all current transmission models in all current truck and bus applications. Allison's worldwide customers now have a new option when selecting transmission fluid. Customers may continue to choose from a wide variety of approved DEXRON®-III or Allison C4 quality fluids or they may elect to switch to TRANSYND™ and extend drain intervals. TRANSYND™ has been shown to be cost effective by reducing maintenance through extended drain intervals while providing superior performance. Benefits may be optimized in severe vocations such as transit fleets where there are more vehicles and fluid change intervals tend to be more frequent. Similar savings may also be achievable in general (lighter) duty vocations such as school buses, motor homes, etc.

Truck OEM's, fleetowners, and truck drivers have a variety of criteria for a transmission system. Easy installation, high reliability, good fuel economy, long clutch life and ease of use are important goals. Concept comparisons between two types of automated mechanical transmissions, torque converter automatics and manual transmissions are discussed. Based on this study a highly integrated transmission system was developed. The fully automatic solution combines the cost advantages of a manual with the comfort and ease of a converter automatic transmission. One feature of the automated manual is that no clutch pedal is required. The transmission system comunicates with other vehicle systems via a CAN-bus data link. The concept of the electropneumatic components is shown, including the selected integration of sensors, actuators and microprocessor controls into separately testable modules.

Distribution of traction forces among driving wheels is one of the main factors governing the performance of a highway truck during acceleration and braking on varying macro and micro road surface conditions. Comprehension of the interaction between wheels and road surface provides a profound systematic way to simulate a truck's motion and design required components for the optimal performance. The development of electronic technologies has created the pre-conditions necessary to develop systems with controlled parameters. However, to realize the pre-conditions, vehicle dynamics problems have to be formulated and solved for both optimization and control. Many different approaches emerged with the aid of electronics to control the circumferential wheel forces (wheel torque) by restricting wheel slip. A part of such systems has been named as Acceleration Slip Regulation (ASR) and Anti Slip Differentials (ASD).

This paper deals with our surveyprofiles of several types of road surfaces, which was intended to provide the basis for establishing such critical design, as well as with our study to predict durability of heavy-duty vehicles. First, road profile measurements were conducted to evaluate evenness of various roads and then attempts were made to evaluate road evenness. Second, the test dump truck traveled over the surveyed road sections and cumulative damage fatigue caused by the road inputs is analyzed by Miner's law and the simulation of the vehicle dynamics. Finally, correlation between road profiles and durability of the heavy vehicle is reviewed schematically.

This paper shows the use of dedicated short range communications, DSRC, as a resource as implemented in a LAN environment. Customer wants and needs are reviewed in light of the requirements for trucking companies to reach 100% utilization of assets and to pursue the constant goal of lowering operating costs. The user perspective of applications are discussed with respect to lane based versus area based data collection. Multiple applications are satisfied from multiple departmental needs. Application design considerations are discussed for using this wireless communication.

Tractors are generally provided with step and grab rail systems to facilitate driver entrance and exit from the cab. However, many of these systems are not designed based on human factors engineering principles, particularly anthropometry and thus are not always used. Some examples include steps or rails that are too high for a cross-section of the population to reach or steps that are difficult to see as the occupant descends from the cab. Trailers frequently do not have any “designed steps/grab rails” to aid the driver or material handler in safely climbing up or down from the rear of the unit. As a result, squat jumping from the trailer floor down to the ground is a common method of exit from commercial trailers. Injuries resulting from exiting commercial vehicles could represent a substantial cost to businesses operating these equipment.

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.

The electrical system of a commercial vehicle is a critical component for reliable vehicle operation. While the demands on today's electrical system have increased dramatically due to higher horsepower engine environments and increased key-off loads, the design of these systems continues to evolve in order to meet these demands. Unfortunately, this design evolution has not kept pace with user expectations for enhanced performance, durability and reduced maintenance of the electrical system. In support of the TMC's S.1 Tomorrow's Truck initiative, this paper offers the following vision of future alternator requirements that will fulfill the expectations of commercial vehicle drivers, maintenance and support personnel. The intent of this vision is that it be used by designers and vehicle manufacturers as a guideline of desirable features for the alternators of tomorrow's truck.

In response to a perceived need by a variety of commercial and personal users for high quality 60 Hz 120/240 volt electric power on board vehicles at any engine speed, the “AuraGen™ Mobile Generator” system with 5 kW user power capacity has been designed, built, tested, and installed on a variety of automotive platforms. The technical solutions to several significant design challenges, involving capacity, manufacturing cost, physical volume, and integration, are described and discussed. A variety of data indicating the characteristics of the power, operational conditions, and efficiency are shown.

Motor racing circuit barrier systems have traditionally been tested by impacting them with, typically, a 780kg, 450mm x 450mm flat impactor, at a velocity of 12m/s (43.2kph). Since the adoption of energy absorbing nose-cones on Formula1 and other single-seater racing cars, which are subject to an FIA impact test into a rigid barrier, it has become necessary to develop a more appropriate barrier test to take into account the compatibility between the sharp, rigid nose-cone and the relatively soft tyre barriers that are used on circuits world-wide. The FIA commissioned the Transport Research Laboratories (TRL) in the UK, to carry out a series of barrier impact tests using a Formula 3000 nose-cone mounted on the 780kg impacting trolley, at speeds of 16.7m/s (60kph) and 22.2m/s (80kph).

Preliminary development and testing has been conducted on two energy-absorbing safety devices for racing circuits, termed the Fitch Inertial Barrier and the Compression Barrier. The first is an array of sacrificial modules, filled with sand and/or water progressively weighted. It is a racing version of inertial barriers used for 30 years on highways in 50 States. In its test, the Inertial Barrier recorded a 4.7 average G deceleration in 36 feet, compared with a 70 G deceleration for a car hitting a concrete barrier head-on with 2.3′ of crush. In the test of the compression barrier, 15 avg. longitudinal Gs were recorded in less than 3 feet of energy-absorption. It reduced the speed of the car by nearly half and reduced rebound by 5 degrees. The barrier self-restored after impact.

In the '97 Dakar Rally, Hino FT model, 8,000cc engine truck, won 1st, 2nd and 3rd places by defeating upper class trucks having engine of 19,000cc. The average speed of the '97 Hino model was increased more than 15 km/h over the '96 model by improving the riding comfort and handling stability. Larger diameter tires, and softer parabolic leaf springs with long and inclined axle-locus for reducing road impact, gas charged dampers, suspension rods which control compliance-steer-motion and wind-up motion of unsprung masses were adopted for the '97 model.

The process and the tools that are used for engineering an optimum engine air-flow subsystem are critical for the successful execution of an engine program. From the perspective of the Air-Flow Subsystem Engineer, the requirements and concept subsystem of components, component subsystem, engine subsystem, and vehicle system engineering processes are described. Additionally, applicable tools such as benchmarking, engine cycle simulation, vehicle simulation, computational fluid dynamics, steady air-flow bench, engine dynamometer, and vehicle testing are explained. As an example, this paper illustrates the process by which a modern, high-performance, high-volume production-intent engine air-flow subsystem, in particular, the intake manifold component, is engineered and how these tools are applied.

Predictable handling of a racecar may be achieved by tailoring chassis stiffness so that roll stiffness between sprung and unsprung masses are due almost entirely to the suspension. In this work, the effects of overall chassis flexibility on roll stiffness and wheel camber response, will be determined using a finite element model (FEM) of a Winston Cup racecar chassis and suspension. The FEM of the chassis/suspension is built from an assembly of beam and shell elements using geometry measured from a typical Winston cup race configuration. Care has been taken to model internal constraints between degrees-of-freedom (DOF) at suspension to chassis connections, e.g. t ball and pin joints and internal releases. To validate the model, the change in wheel loads due to an applied jacking force that rolls the chassis agrees closely with measured data.