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Improved performance creates a need for a limited slip differential for widespread application. Existing types suffer from the disadvantage of high cost and they are generally not well suited to front wheel drive applications. The ‘Suretrac’ differential meets this enhanced requirement. In this new design torque is transmitted through the unit using a cam and follower principle. Any relative rotation of the cams on the output shafts is opposed by friction forces which generate a torque ratio between the output shafts. The design is novel in using helical faces to give large contact areas and avoid high Hertzian stresses. The performance of this type of differential differs from viscous types or traction control because the torque difference is established before any relative motion takes place. The tyre dynamics dictate the torques generated so that the differential always provides the optimum torque balance. This maintains tyre adhesion and enhances directional stability and safety.

This paper introduces and discusses a new 2D physical model which has been developed and validated in order to study and optimize the handling behavior of the tire. It can be divided into two parts, the structural model and the contact area model. The parameters, that are function of the vertical load, are identified or calculated by comparison with the results provided by 3D finite element models. The input data for the identification procedure consist of a set of frequency responses performed on the finite element model. A second set of simulations on the 3D model of the tread pattern gives the characteristics of the contact model. Once built the 2D model it is easy to carry out both steady state and transient analysis. The steady state analysis returns the cornering carpet, in terms of lateral force and self-aligning moment as function of the cornering angle. The transient analysis allows the evaluation of the relaxation length and dynamic characteristics.

The newly developed optical measuring system allows adjustment of front and rear wheel angularities - toe, camber, caster - in assembly-line production. There is no need to align the car, since the measuring base for the angle alignment is formed by the car itself. Defined spring compression values and direct caster angle determination lead to higher accuracy. Adjustment is carried out directly on the assembly line. Measuring pits are not required. The working time for each car and the working area required, which are important cost factors, are markedly lower than with conventional instruments. The axle measuring system was developed for the VW Vanagon, but can also be used for passenger car chassis. This present paper describes the measuring principle, the optical and mechanical design of the device, and a statistical analysis of over 100 cars aligned by means of this system, in comparison with conventional measuring instruments.

This paper includes a brief description of present day rear axle designs and their bearings. It also includes a complete discussion of the design objectives of a new concept in single row tapered roller bearings and of the design features of this new bearing. The new bearing is preadjusted and carries thrust loads in either direction, as well as radial loads in any combination. A detailed discussion of its development and testing, both laboratory and field, is presented.

A concept of an entirely new single point tandem axle suspension designed only for highway operation, featuring a torsion rubber spring, independent wheel action, high spring deflection, controlled axle movement, and maximum arm articulation is presented. A superior ride, easier steering, reduced tire wear, weight reduction, ease of maintenance, elimination of friction, no lubrication required, and a balanced driveline under all load conditions are featured. NOTE: This is not a walking beam design of a suspension. This paper attempts to give as broad a picture as possible of the design, development, testing and operational features of the suspension.

Most vehicles designed primarily for off-road use - whether for the SUV, military, agricultural or earthmoving industries - employ all wheel drive systems. For off-road conditions where the traction is limited by the deformable nature of the ground, for example, loose track, soil or sand, providing a drive torque to all the wheels is the obvious design solution for maximising the total tractive effort. For military or commercial vehicles, this results in optimum mobility in difficult terrain, whereas for agricultural or earthmoving vehicles it often results in optimum work rates. In order to analyse the performance of off-road vehicles, it is necessary to understand the torque and power flows through the driveline system to each axle or wheel. The research presented in this paper focuses on the use of novel, non-contact torque sensors to measure the driveline torque distribution.

Heavy-duty vehicles are primarily powered by diesel fuel, emitting CO2 emissions regardless of the exhaust after-treatment system. Contrastingly, a hydrogen engine has the potential to decarbonize the transportation sector as hydrogen is a carbon free, renewable fuel. In this study, a multi-physics 1D simulation tool (GT-Power) is used to model the gas exchange process and performance prediction of a two-stroke hydrogen engine. The aim is to establish a maximum torque-level for a four-stroke hydrogen engine and then utilize different methods for two-stroke modeling to achieve similar torque by optimizing the gas exchange process. A camless engine is used as base, enabling the flexibility to utilize approximately square valve lift profiles. The preliminary step is the GT-Power model validation, which has been done using diesel and hydrogen engines (single-cylinder heavy-duty) experiments at different operating points (871 rpm, 1200 rpm, 1259 rpm, and 1508 rpm).

In some situations, designers need quick and powerful instruments to provide information for philosophical choices in powertrain layout. The increase of computational capabilities favors the implementation of complex equations and the possibility of making powerful software for supporting technical decisions. The paper presents a numerical model of a shaft that provides information about shaft dynamic and structural behavior. The model can be used for simulating gearbox shaft, drive shaft or axle shaft. By means of a MATLAB/Simulink® model, a finite element (FE) procedure is implemented: the shaft is depicted as its inertial and stiffness features and it is also possible to evaluate stresses, strains and boundary condition forces. In addition, MATLAB/Simulink® powerful allows evaluating shaft behavior during working or test conditions, such as the abuse maneuver, and not only in an abstract situation used by analysts for structural and dynamic calculations.

Next generation vehicles are under environmental and economic pressure to reduce emissions and increase fuel economy, while maintaining the same ride and performance characteristics of present day combustion engine automobiles. This has prompted researchers to investigate hybrid vehicles as one possible solution to this challenge. At Southwest Research Institute (SwRI), a unique parallel hybrid drivetrain was designed and prototyped. This hybrid drivetrain alleviates the disadvantages of series hybrid drivetrains by directly coupling the driving wheels to two power sources, namely an engine and an electric motor. At the same time, the design allows the engine speed to be decoupled from the vehicle speed, allowing the engine to operate at its most efficient state. This paper describes the drivetrain, its components, and the test stand that was assembled to test the parallel hybrid drivetrain.

This paper discusses the torque-fill capability of a novel hybrid electric drivetrain for a high-performance passenger car, originally equipped with a dual-clutch transmission system, driven by an internal combustion engine. The paper presents the simulation models of the two drivetrains, including examples of experimental validation during upshifts. An important functionality of the electric motor drive within the novel drivetrain is to provide torque-fill during gearshifts when the vehicle is engine-driven. A gearshift performance indicator is introduced in the paper, and the two drivetrain layouts are assessed in terms of gearshift quality performance for a range of maneuvers.

Thermal management systems (TMS) of armored ground vehicle designs are often incapable of sustained heat rejection during high tractive effort conditions and ambient conditions. During these conditions, which mainly consist of high torque low speed operations, gear oil temperatures can rise over the allowable 275°F limit in less than twenty minutes. This work outlines an approach to temporarily store excess heat generated by the differential during high tractive effort situations through the use of a passive Phase Change Material (PCM) retrofit thereby extending the operating time, reducing temperature transients, and limiting overheating. A numerical heat transfer model has been developed based on a conceptual vehicle differential TMS. The model predicts the differential fluid temperature response with and without a PCM retrofit. The developed model captures the physics of the phase change processes to predict the transient heat absorption and rejection processes.

The driveshafts can be an important contributor to vehicle interior noise including low-frequency (booming) noise where the vibrations, originating in the powerplant, travel to the vehicle body through the driveshafts. A suitable Key Performance Indicator (KPI) for the driveshaft performance is the transmissibility, which is an output/input acceleration ratio and can be used to describe the amount of vibration transferred from the inboard to the outboard joint of the driveshaft. This paper introduces a simple physical model of the driveshaft transmissibility able to support the development and evaluation of the driveshaft and to estimate the effectiveness of countermeasures such as a dynamic damper. The model is validated through comparison with on-vehicle measurements. The proposed approach offers ease of use, low computational cost and clear relation of the measured transmissibility with the system’s physical properties.

Wheel hubs typically are set in vehicles through nuts with self-locking feature to assure safety. That feature may be done by an external component like a cotter pin, a deformable element incorporated to the nut like polyamide or metallic insert or some controlled mechanical deformation applied right on nut body. Nuts with some self-locking elements are being used in order to eliminate cotter pins from the system. However, during the maintenance of vehicles, some disadvantages appear like damage in thread axle due disassembling, considering controlled mechanical deformation nuts or the replacement of nut with polyamide insert to assure self-lock featuring. This paper presents a solution to replace a fastening in a current front and rear wheel-hub for a passenger vehicle. The study is made comparing a current solution, a controlled mechanical deformed nut - stover type - from a polyamide insert nut and an innovative prevailing torque nut with incorporated washer.

A nonlinear finite element passenger car radial-ply tire model was developed to investigate a tire's three-dimensional transmissibility in the X, Y, and Z directions. The reaction forces of the tire axle in longitudinal (X axis), lateral (Y axis), and vertical (Z axis) directions were recorded when the tire encountered a cleat, and then the FFT (Fast Fourier Transform) algorithm was applied to extract tire's transient response information in the frequency domain. The result showed that this passenger car tire has clear peaks at 47-51 and 91-92 Hz longitudinal, 41-45 Hz lateral, and 80-83Hz vertical. An analytical rigid ring model was also formulated, based on the dynamic equations of the rigid ring tire model. The characteristic equations were obtained and solved for eigenvalues and eigenvectors, which represent tire's free vibration natural frequencies and mode shapes.

Rear disc brakes were released as standard equipment on 1975 Mark IV and as a regular production option on 1975 Lincoln, Thunderbird, and Mercury. This brake is the result of a joint Ford/Kelsey-Hayes design and development effort. The key feature is a single-piston sliding caliper with an integral, self-adjusting parking brake mechanism. The design offers great flexibility in packaging on various car lines and on different axles. This paper describes the major features of the design and the significant problems found and overcome in the development program.

Aerodynamic aids, such as spoilers, applied to the rear of cars can provide drag reduction to improve performance, or can enhance high speed stability by reducing lift at the rear axle. In some cases these can be conflicting demands. It has been noted, however, that when rear axle lift is reduced there is often a reduction in yawing moment which has a beneficial effect on crosswind sensitivity. Wind tunnel results from real road vehicles are presented to illustrate this effect. This beneficial relationship is further explored in a wind tunnel experiment using simple models to represent road vehicles. Force and moment coefficients as a function of yaw angle are measured for a range of vehicle geometries which generate a substantial variation in lift. It is shown that as lift is reduced, yawing moment is also reduced, while side force and rolling moment are increased.

The electric vehicle market in India has tremendous growth potential in the upcoming years and decades, attracting numerous automotive manufacturers, including Tier-1 suppliers, seeking to participate in this growth phase. Electric powertrains used in e-cars on Indian roads comply with BIS and AIS standards. However, these standards alone do not provide sufficient clarity on the complete list of tests required for developing an e-Axle through all stages of development. Developing the e-Axle in-house for the Indian market poses a significant challenge for OEMs and Tier-1 suppliers, as it will play a crucial role in overall profitability at high volumes in the long term. Adhering solely to the BIS and AIS standards may prove insufficient in fulfilling the developmental prerequisites of an electric axle (e-Axle) system.

Abstract The Noise, Vibration, and Harshness (NVH) performance of automotive powertrain (PT) mounts involves the PT source vibration, PT mount stiffness, road input, and overall transfer path design. Like safety, performance, and durability driving dynamics, vehicle-level NVH also plays a major contributing factor for electric vehicle (EV) refinement. This article highlights the recent research on PT mounting-related NVH controls on electric cars. This work’s main contribution lies in the comparative study of the internal combustion engine (ICE)-based PT mounting and EV-based PT mounting system (PMS) with specific EV challenges. Various literature on PT mounts from the passive, semi-active, and active mounting systems are studied. The parameter optimization technique for mount stiffness and location by various research papers is summarized to understand the existing methodologies and research gap in EV application.

This paper presents the characteristics of more than 260 trim levels for over 50 production electric vehicle (EV) models on the market since 2014. Data analysis shows a clear trend of all-wheel-drive (AWD) powertrains being increasingly offered on the market from original equipment manufacturers (OEMs). The latest data from the U.S. Environmental Protection Agency (EPA) shows that AWD EVs have seen a nearly 4 times increase in production from 21 models in 2020 to 79 models in 2023. Meanwhile single axle front-wheel-drive (FWD) and rear-wheel-drive (RWD) drivetrains have seen small to moderate increases over the same period, going from 9 to 11 models and from 5 to 12 models, respectively. Further looking into AWD architectures demonstrates dual electric machine (EM) powertrains using different EM types on each axle remain a small portion of the dual-motor AWD category.

Optimizing/maximizing regen braking in a hybrid electric vehicle (HEV) is one of the key features for increasing fuel economy. However, it is known [1] that maximizing regen braking by braking the rear axle on a low friction surface results in compromising vehicle stability even in a vehicle which is equipped with an ESP (Enhanced Stability Program). In this paper, we develop a strategy to maximize regen braking without compromising vehicle stability. A yaw rate stability control system is designed for a hybrid electric vehicle with electric rear axle drive (ERAD) and a “hang on” center coupling device which can couple the front and rear axles for AWD capabilities. Nonlinear models of the ERAD drivetrain and vehicle are presented using bond graphs while a high fidelity model of the center coupling device is used for simulation.