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NAIPC reflects modern developments in alternative, electrified propulsion systems, high tech gasoline, diesel ICEs, hydrogen fuel cells, battery electric systems, variable transmissions.

Two new 4 X 4 drivetrain systems have been developed for highway tractors that are used to pull multiple trailer combinations. The first one is a 4 X 2 that automatically becomes a 4 X 4 when conditions exist that require 4 X 4 operation. The second one is a full-time 4 X 4 that proportions the drive torque 36% to the front axle and 64% to the rear axle. A unique front driving steering axle has also been developed that permits a 4 X 4 system to be installed in a standard 4 X 2 truck. There is no need to relocate any major components to make space available for a front driving steering axle.

A braking force distribution strategy in integrated braking system composed of the main braking system and the auxiliary braking system based on braking pad wear control and hitch force control under non-emergency braking condition is proposed based on the Electronically Controlled Braking System (EBS) to reduce the difference in braking pad wear between different axles and to decrease hitch force between tractors and trailers. The proposed strategy distributes the braking force based on the desired braking intensity, the degree of the braking pad wear and the limits of certain braking regulations to solve the coupling problems between braking safety, economical efficiency of braking and the comfort of drivers. Computer co-simulations of the proposed strategy are performed.

This paper starts with an analysis of design configurations of the drivelines with different power-dividing units (PDUs) of main dump truck manufacturing companies. As it follows from the analysis, improvements of articulated truck energy efficiency and reduction of fuel consumption by optimizing the power distribution to the drive wheels are still open issues. The problem is that a variety of operating and terrain conditions of dump trucks requires different wheel power distributions that cannot be provided by one set of PDUs employed in a truck. The central PDU in the transfer case was identified as the most important PDU among the five PDUs, which plays a crucial role in the power distribution between the front axle and the rear tandem of a 6×6 articulated dump truck. The paper formulates a constraint optimization problem to minimize the tire slippage power losses by optimizing the power distribution between the drive wheels.

A new hydro-mechanical coupling has been developed for use as a slip limiting device in differentials, axle and transfer cases as well as a stand alone, self contained transmission coupling for all wheel drive applications. The exceptional torque capacity to packaging size ratio of this device allows secondary axles to be driven exclusively through the coupling before or after the final drive reduction. In this paper, the operation principle and general construction of the Gerodisc type coupling devices are discussed as well as analysis and comparison of theoretical performance capabilities, laboratory bench test data and actual on vehicle field testing data.

Environmental concerns and government regulations are factors that have led to an increased focus on fuel economy in the automotive industry. This paper identifies a method used to improve the efficiency of a front-wheel-drive (FWD) automatic transmission. In order to create improvements in large complex systems, it is key to have a large scope, to include as much of the system as possible. The approach taken in this work was to use Design for Six Sigma (DFSS) methodology. This was done to optimize as many of the front-wheel-drive transmission components as possible to increase robustness and efficiency. A focus of robustness, or consistency in torque transformation, is as important as the value of efficiency itself, because of the huge range of usage conditions. Therefore, it was necessary to find a solution of the best transmission component settings that would not depend on specific usage conditions such as temperatures, system pressures, or gear ratio.

Heavy commercial vehicle axle shafts are designed for torsion load. Typically, axle shaft fracture mode during the test is torsional in nature through either shaft body diameter or spline end. However, some of the field return axles shows fracture mode on axle shaft flange. This fracture mode does not resemble with a typical lab test torsional fracture. Metallurgical investigation report indicated that the fracture mode is bending in nature. This paper thus focuses on detail study of change in boundary condition and load transfer path under abusive vertical bending load on axle. A detail finite element analysis is performed to understand stress state change in axle shaft under this condition. A fracture hypothesis is proposed based on observations of finite element analysis results. A detail case study is presented depicting correlation of proposed hypothesis with physical fracture mode.

Adjuster rings are used in commercial vehicle axle assembly to preload differential bearings and provide support in the axial direction. Adjuster along with the carrier and bearing cap combined to form a threaded joint. Adjuster with external threads engages with internal threads formed in carrier and bearing cap. Preload in differential assembly maintains the system rigidity and helps to maintain an optimized hypoid gear engagement. An adequate preload is important to achieve a desirable bearing life. Reduction in thread engagement at adjuster joint fully or partially will cause a reduction in preload and can lead to gear misalignment. This can cause severe durability concerns. In some cases, it is observed that under vehicle operating loads adjuster ring is backed off from its assembled condition by bending the split pin (split pin is, positive lock, used to maintain adjuster position) and adjuster threads were stripped off.

The simulation of the longitudinal performance of trucks and articulated vehicles requires careful attention to tandem axle dynamics, the brake system model, and the tire model. The approach which was taken to these problems in a recently developed digital simulation is given. Results for the braking performance of an articulated vehicle and a straight truck are compared to empirical data. In addition, simulation results are given for the articulated vehicle equipped with a simple antiskid system.

In this course, participants will be exposed to various methods that can be used to accomplish an efficient, robust & quiet running drivetrain. This course focuses on the terms, functions, nomenclature, operating characteristics and effect on vehicle performance for each of the drivetrain components. Participants will receive an introduction to the various components of the drivetrain, including the clutch or torque converter, manual or automatic transmission, driveshaft, axle, wheel ends, and brakes.

In this study the finite element method is used to simulate a light truck multi-leaf spring system and its interaction with a driven axle, u-bolts, and interface brackets. In the first part of the study, a detailed 3-D FE model is statically loaded by fastener pre-tension to determine stress, strain, and contact pressure. The FE results are then compared and correlated to both strain gage and interface pressure measurements from vehicle hardware test. Irregular contact conditions between the axle seat and leaf spring are investigated using a design of experiments (DOE) approach for both convex and discrete step geometries. In the second part of the study, the system FE model is loaded by both fastener pre-tension and external wheel end loads in order to obtain the twist motion response. Torsional deflection, slip onset, and subsequent slip motion at the critical contact plane are calculated as a function of external load over a range of Coulomb friction coefficients.

A novel transmission has been designed, built, and tested utilizing a traction continuously variable drive and a planetary traction fixed ratio drive. This paper describes the design of the transmission both in terms of power flow concept and in new component construction. The continuously variable drive and planetary are combined in a scheme whereby three modes of power flow are meshed to provide a high continuously variable ratio range of more than 20:1 overall. Neutral and reverse are available with no additional hardware. The transmission was installed in a half ton pick-up truck for testing the concept as a high ratio vehicle transmission.

The proprietary CVT technology introduced at the 1991 SAE International Truck & Bus Meeting & Exposition in Chicago has subsequently gone through numerous design iterations and is currently in the second generation hardware stage. Ongoing optimization of the hardware has resulted in overall system performance which meets or exceeds initial predictions, thereby assuring suitability for all automotive applications.

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 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.

Taking a good longitudinal braking performance on flat and level road of tractor and semi-trailer combination as a target, in order to achieve an ideal braking force distribution among axles, while the vehicle deceleration is just depend on the driver's intention, not affected by the variation of semi-trailer mass, the paper proposes a model based vehicle mass identification and braking force distribution strategy. The strategy identifies the driver's braking intention via braking pedal, estimates semi-trailer's mass during the building process of braking pressure in brake chamber, distributes braking force among axles by using the estimated mass. And a double closed-loop regulation of the vehicle deceleration and utilization adhesion coefficient of each axle is presented, in order to eliminate the bad effect of mass estimation error, and enhance the robustness of the whole algorithm. A simulation is conducted by utilizing MATLAB/Simulink and TruckSim.

Overloading of trucks can easily cause damage to roads, bridges and other transportation facilities, and accelerate the fatigue loss of the vehicles themselves, and accidents are prone to occur under overload conditions. In recent years, various countries have formulated a series of management methods and governance measures for truck overloading. However, the detection method for overload behavior is not efficient and accurate enough. At present, the method of dynamic load identification is not perfect. No matter whether it is the dynamic weight measurement method of reconstructing the road surface or the non-contact dynamic weight measurement method, little attention is paid to the difference of different vehicles. Especially for different vehicles, there should be different load limits, and the current devices are not smart enough.

An organic Rankine Bottoming cycle added to Diesel engines used for long-haul trucks has the potential of improving their peak fuel economy by up to 15% over a typical duty cycle. General Electric has developed a multi-vane rotary expander which has a measured isentropic brake efficiency of 80+% over a wide range of speed and power levels with organic working fluids. High cycle efficiency for design and off-design conditions is achieved with the multi-vane expander. The potential advantages of the multi-vane expander for the Diesel engine bottoming cycle include the elimination of a high speed gear box and the potential for over 80% isentropic engine efficiency. The multi-vane expander is a ruggedly built component running at Diesel engine speed. This paper describes the design and evaluation of a nominal 40 HP multi-vane expander for this application.

Developed to cut down on maintenance costs and increase the earning power of the vehicle, this family of suspensions provides for improved vehicular behavior - items such as stability, braking, cornering, and overall ride. The suspensions utilize a principle of providing a cushioned variable rate ride through the use of molded rubber springs. Floating walking beams distribute weight equally on both axles in the case of tandems. The axles are positively located by upper wishbones and lower torque rods. The parallelogram thus formed prevents windup and axle hop. The correct use of metals shows a substantial weight saving in the entire model range.

In the course of studying the market requirements for seals in large axles and relating this to conventional sealing technology, it became apparent that a fresh approach to sealing was desirable. This paper describes such a development in detail. Centrifugal action is the principle sealing action of the seal. Although this is in itself not new, the method by which it is harnessed makes the design radically different from normal “slinger” seals. Both practical and analytical work are covered in the text.