Browse Topic: Limited slip differentials

Items (88)

Millers Oils tackles EV lubrication challenges

18AUTP10_0910/01/2018

Although electric vehicles (EVs) often are extolled as “low-maintenance” alternatives to conventional internal-combustion (IC) propulsion and its brew of critical fluids that require routine maintenance, EV drivetrains also rely on proper lubrication-and in many senses pose performance challenges at least equal to those of IC drivetrains. Not the least of electric drivetrains' unique stresses on lubrication: electric motors can deliver maximum torque at zero rpm.

Birch, Stuart

Automatic Drive Train Management System for 4WD Vehicle Based on Road Situation Identification

2018-01-098704/03/2018

The slip ratio of vehicle driving wheels is easily beyond a reasonable range in the complex and changeable driving conditions. In order to achieve the adaptive acceleration slip regulation of four-wheel driving (4WD) vehicle, a fuzzy control strategy of Automatic Drive Train Management (ADM) system based on road situation identification was proposed in this paper. Firstly, the influence on the control strategy of ADM system was analyzed from two aspects, which included the different road adhesion coefficients and the vehicle’s ramp driving state. In the meantime several quantitative expressions of relevant control parameters were derived. Secondly, the fuzzy logic control algorithm was adopted to design a road situation identification subsystem and a ramp driving state identification subsystem respectively. The former was based on the μ-S curve model, and the latter was based on the vehicle driving equilibrium equation. Thirdly, the physical model of limited slip differential was

Ke, Min, Zhu, Bing, Zhao, Jian, Deng, Weiwen

WHAT WE'RE DRIVING

18AUTP02_1502/01/2018

It isn't every carmaker that introduces its new model with a session on a tight and slippery test track. But when it's a 1955-kg (4090-lb) sedan with 450 kW (603 hp) and 850 N·m (627 lb·ft) available at the shove of a foot, it is a useful education. That's what Mercedes-Benz offers its U.K. buyers of the new Mercedes-AMG E 63 S 4Matic+.

Effect of Temperature on Braking Efficiency Stability of Magnetorheological Fluid Auxiliary Braking Devices

2017-01-251009/17/2017

Fluid auxiliary braking devices can provide braking torque through hydraulic damping, fluid auxiliary braking devices can also convert vehicular inertia energy into transmission fluid heat energy during the braking, which can effectively alleviate the work pressure of the main brake. Traditional hydraulic auxiliary braking devices use transmission fluids to transmit torque, however, there is a certain lag effect during the braking. The magnetorheological fluid (MR fluid) can also be used to transmit torque because it has the advantages of controlling braking torque linearly and responding fast to the magnetic field changed. The temperature of MR fluid will increase when the vehicle is engaged in continuous braking. MR fluid temperature changes will cause a bad influence on the efficiency stability of auxiliary braking. So it is necessary to clear about the effect of temperature on MR fluid auxiliary braking torque in order to keep the braking efficiency stability through torque

Xiong, Shengguang, Tan, Gangfeng, Yang, Bo, Xiao, Longjie, Xu, Yongbing, Wang, Yishi

Study on the Effects of Magnetic Field on Magnetorheological Fluid Hydraulic Retarder Braking Torque

2017-01-250309/17/2017

In order to ensure driving safety, heavy vehicles are often equipped with hydraulic retarder, which provides sustained, stable braking torque and converts the vehicle kinetic energy into heat taken away by the cooling system when traveling on a long downhill. The conventional hydraulic retarder braking torque is modulated by adjusting the liquid filling rate, which leads to slow response and difficult control. In this paper, a new kind of magnetorheological (MR) fluid hydraulic retarder is designed by replacing the traditional transmission oil with MR fluid and arranging the excitation coils outside the working chamber. The braking torque can be controlled by the fluid viscosity of MR fluid with the variation of magnetic field. Compared with the traditional hydraulic retarder, the system has the advantages of fast response, easy control and high adjustment sensitivity. To find out the influence of the magnetic field on the proposed MR fluid retarder braking torque, the fluid dynamics

Mei, Binyu, Guo, Xuexun, Yang, Bo, Xiong, Shengguang, Tan, Gangfeng

Evaluation of Stability and Control of Movement of 6x6 Truck for Different Operating Modes

2017-01-157503/28/2017

Trucks are one of the most common modes of transport and they are operated in various road conditions. As a rule, all-wheel drive trucks are equipped with special systems and mechanisms to improve their off-road capability and overall efficiency. The usage of blocked mechanisms for power distribution is one of the most popular and effective ways to improve the off-road vehicle performance. However, the lock of differential may adversely affect the stability and control of vehicle because of the unobvious redistribution of reactions acting on wheels, which consequently leads to poor performance and safety properties. Problems of rational distribution of power in transmissions of all-wheel drive vehicles, as well as research in the field of improving directional stability and active safety systems are among the priorities in modern automotive industry. To study dynamics of a vehicle with wheel formula 6x6 a mathematical model of the vehicle was developed in an environment of LMS Amesim

Keller, Andrei, Aliukov, Sergei, Anchukov, Vladislav

Positive Difflock Stopper for Off Road Vehicles

2015-26-014301/14/2015

The purpose of a differential is to allow the wheels of an automobile to turn at different speeds so that it does not skid during turning. However when a vehicle runs on a slick or muddy surface (especially in Agricultural and constructional Field applications) that same feature causes the wheel with less traction to spin freely as this unit transmits power to the tire with least amount of traction. The function of a difflock is to lock the differential gears, by locking the differential, both the axles receive equal power and hence equal traction is available at both the tires. This Paper describes the positive locking of a differential by stopper, and also in detail the problems associated with its engagement and disengagement in tractors and construction equipment's. Additionally a concept for a difflock stopper which has been experimentally proven for tractors and construction equipment's is also discussed.

Chaudhari, Navneet, Srinivasa, K.V.V. Rao, Cecil, Phillips

Torque Vectoring Control for Distributed Drive Electric Vehicle Based on State Variable Feedback

2014-01-015504/01/2014

Torque Vectoring Control for distributed drive electric vehicle is studied. A handling improvement algorithm for normal cornering maneuvers is proposed based on state variable feedback control: Yaw rate feedback together with steer angle feedforward is employed to improve transient response and steady gain of the yaw rate, respectively. According to the feedback coefficient's influence on the transient response, an optimization function is proposed to obtain optimum feedback coefficients under different speeds. After maximum feedforward coefficients under different speeds are obtained from the constraint of the motor exterior characteristic, final feedforward coefficients are calculated according to an optimal steering characteristic. A torque distribution algorithm is presented to help the driver to speed up during the direct yaw moment control. Simulations performing multiple maneuvers are carried out: The transient response and the steady gain of the yaw rate are improved; the

Feng, Yuan, Yu, Zhuoping, Xiong, Lu, Liu, Jun, Jin, Chi

Mobility and Energy Efficiency Analysis of a Terrain Truck

2013-01-067204/08/2013

While much research has focused on improving terrain mobility, energy and fuel efficiency of terrain trucks, only a limited amount of investigation has gone into analysis of power distribution between the driving wheels. Distribution of power among the driving wheels has been shown to have a significant effect on vehicle operating characteristics for a given set of operating conditions and total power supplied to the wheels. Wheel power distribution is largely a function of the design of the driveline power dividing units (PDUs). In this paper, 6×6/6×4 terrain truck models are analyzed with the focus on various combinations of PDUs and suspension systems. While these models were found to have some common features, they demonstrate several different approaches to driveline system design. In order to further investigate the effect of wheel power split on mobility and energy/fuel efficiency in conjunction with suspension characteristics, this paper provides an analytical method and

Vantsevich, Vladimir V., Murphy, Dennis, Bortolin, Gianantonio

Nomenclature and Terminology for Truck and Bus Drive Axles

J923_201207 (Current)07/02/2012

This SAE Recommended Practice outlines basic nomenclature in common use for truck and bus drive axle designs. Over a period of years there have been many different designs introduced; however, for this report, only the most common have been selected and only their general construction is illustrated to show the nomenclature of the various parts.

Truck and Bus Powertrain Committee

Development of Front-Wheel-Drive ELSD for Efficient Performance and Safety

2012-01-030504/16/2012

The open (standard) differential provides an important function in vehicle dynamics and handling by splitting the applied driveline torque and allowing each wheel or axle to spin at different speeds. This function is necessary to eliminate axle bind-up while negotiating turns. However, it inherently impedes optimal traction and mobility performance by allowing the available torque to be limited by the wheel or axle having the least amount of traction. Loss of traction could result in loss of driveline torque control and a resulting loss of vehicle control. This loss of control could be catastrophic in the case of higher speed maneuvers. The proposed electronically controlled hydraulic limited slip differential solution corrects this problem, seamless to the driver, while maintaining the fundamental open differential function. Furthermore, this system maintains efficient forward motion compared to other solutions that slow the vehicle down while expending valuable energy. A number of

Fox, Matthew, Grogg, John

Axle Drive and Brake-Based Traction Control Interaction

2011-01-216009/13/2011

Brake-based traction control systems (TC), which utilize the brake of a spinning wheel of the drive axle, are widely used in passenger cars and light trucks, and recently were applied to all-wheel drive construction equipment. Such machines employ various types of interwheel drive systems (i.e., axle drives such as open differentials, limited slip differentials, etc.) to control torque split between the drive wheels and, thus, improve vehicle traction performance. As experimental research showed, the interaction between the traction control system and the axle drive can lead to unpredictable changes in vehicle performance. Lack of analytical work in this area motivated this study of the interaction and impact of the two systems on each other and the dynamics and performance of a drive axle. The paper presents an analysis of the torque/force distribution between the driving wheels of an axle with open differential and limited slip differential with different torque bias characteristics

Vantsevich, Vladimir V., Bortolin, Gianantonio

High-Performance Differentials, Axles, & Drivelines

C111307/27/2011

Every automobile has a differential and most have axles, yet the exact function of these is not common knowledge. This comprehensive seminar introduces participants to the function and interfaces of axles and their individual components. As we modify cars for street performance or all out race applications, it is important to know the trade-offs in the drivetrain system. The theory and practice of axle systems is introduced along with a hands-on style approach to repairing and modifying axles for high performance applications. For this hands-on approach, actual hardware will be reviewed in an informal setting. The seminar begins by defining the axle fundamentals and operation followed by an in-depth review of original equipment axles, differentials, torque bias, hypoid gears, and rebuild steps. The different manufacturing and service techniques required for different gear architectures is also reviewed. The seminar concludes with a unique applications-specific workshop and industry

Permeability Measurements of Sintered and Paper Based Friction Materials for Wet Clutches and Brakes

2010-01-222910/25/2010

Wet clutches are important components used in the transmission and drive trains of many modern vehicles. The clutches transfer torque via the friction between a number of friction discs and the friction characteristics is therefore of great importance for the overall behavior of the vehicles. The friction characteristics is governed by a number of parameters such as lubricant base oil and additives, type and permeability of the friction material and temperature and surface roughness of the interacting surfaces. The permeability is considered to influence time of engagement and supply the sliding interface with lubricant and additives during engagement. In this work, a permeability measurement method suitable for wet clutch friction materials is thus used to measure the permeability of friction materials of different types; sintered bronze and paper based materials. The investigated friction materials come from different vehicle applications such as Limited Slip Differentials and

Marklund, Pär

Next Generation Torque Control Fluid Technology, Part IV: Using a New Split-μ Simulation Test for Optimizing Friction Material-Lubricant Hardware Systems

2010-01-223010/25/2010

Wet clutch friction devices are the primary means by which torque is transmitted through many of today's modern vehicle drivelines. These devices are used in automatic transmissions, torque vectoring devices, active on-demand vehicle stability systems and torque biasing differentials. As discussed in a previous SAE paper ( 2006-01-3271 - Next Generation Torque Control Fluid Technology, Part II: Split-Mu Screen Test Development) a testing tool was developed to correlate to full-vehicle split-mu testing for limited slip differential applications using a low speed SAE #2 friction test rig. The SAE #2 Split-Mu Simulation is a full clutch pack component level friction test. The purpose of this test is to allow optimization of the friction material-lubricant hardware system in order to deliver consistent friction performance over the life of the vehicle. In this paper we will describe the development of a new test based on the previous work including equipment modifications, data analysis

Whitticar, David, Basu, Shubhamita, Greene, Galen, Henley, Matthew, Parham, Dwight, Prengaman, Christopher, Schiferl, Elizabeth, Baker, Mark, Bartley, Stuart, Huston, Michael E.

Experimental Characterization of Wet Clutch Friction Behaviors Including Thermal Dynamics

2009-01-136004/20/2009

Wet clutches are widely used in automotive systems. They are essential parts of automatic transmissions, modern All-Wheel-Drive systems or dual-clutch transmissions. Regardless of the area of application, a good knowledge of clutch friction behaviors is crucial for the clutch control system development. This paper considers two important factors of the wet clutch dynamics: coefficient of friction behavior and thermal dynamics. An Active Limited Slip Differential wet clutch with carbon fiber-based friction lining material is experimentally characterized by using a precise wet clutch setup. The characterization of the coefficient of friction behavior includes influence of clutch slip speed, applied force, and friction surface temperature. The clutch thermal dynamics is characterized based on the heat power balance law applied to the clutch separator plate with a variable heat transfer coefficient. The results of the thermal model experimental validation are presented, as well.

Ivanović, Vladimir, Herold, Zvonko, Deur, Joško, Hancock, Matthew, Assadian, Francis

An Application of Traction Vectoring to a Formula SAE Car

2008-01-294412/02/2008

The Formula SAE competition is intended to encourage technical development consistent with safety. This paper describes an application of an automated “fiddle brake”, or traction vectoring system to a Formula SAE car. The expected performance advantages of the system over cars equipped with mechanical limited slip differentials is discussed. Test results are included using only a limited slip differential, the limited slip differential plus the new system, and finally the new system and an open differential. The power requirements of the system are discussed. A discussion of some other traction vectoring designs is included.

Bentz, Michael, Becker, Thomas, Cox, David, Janota, Charles, Tarlton, Robert, Ward, Steven, Miller, Norman

Effect of Limited Slip Clutch Friction on the Driveline Dynamics of a Rear Wheel Drive Vehicle Coasting in a Turn

2008-01-158206/23/2008

A model and simulation results are presented for the torsional dynamics of a rear wheel driveline while the vehicle is coasting in a turn. The model includes the effects of road load and powertrain drag, limited slip differential clutch friction, the inertias of the vehicle, wheels, axles, differential carrier, and driveshaft, the final drive ratio, torsional stiffnesses of the axles and driveshaft, vehicle track width, and radius of the turn. The dynamics of coasting in a turn differ from powered driving due to changes in the inertia loading the driveshaft, the damping effect of the disengaged transmission, and nonlinearities in the clutch friction. Specific focus is given to vibration in the axles and driveshaft due to variations in the torque-speed slope of the clutches, which is determined by the slope of the friction coefficient ‘μ’ versus sliding speed ‘v’ in the limited slip clutches. The clutch μ-v slope is strongly influenced by the lubricant in the differential and

Cameron, T. M., Jao, T. C., Hewette, C., McCombs, T., DeGonia, D.

Experimental Setups for Active Limited Slip Differential Dynamics Research

2008-01-030204/14/2008

In order to support active limited slip differential (ALSD) modeling work, a test rig of a DC motor-actuated ALSD has been developed. The test rig is equipped with a torque servomotor that provides a precise closed-loop control of the clutch slip speed, as well as with sensors of clutch torque, and DC motor position and current. In addition to the test rig, a precise wet clutch experimental setup has been developed by using the differential hardware. The setup provides direct measurements of the clutch pack axial force, the separator plate temperature, and the press plate axial position. The paper describes the ALSD test rig and the wet clutch experimental setup, presents and analyzes characteristic experimental results, and outlines the main ALSD modeling results.

Ivanović, Vladimir, Herold, Zvonko, Deur, Joško, Hancock, Matthew, Assadian, Francis

Research on Self-adaptive 4WD System

2007-01-375308/05/2007

Depending on good stability and pass ability on adverse road conditions, 4WD system is being attached importance by vehicle industry gradually. Traditionally, 4WD is mechanical or viscous type, but its performance is difficult to adapt to dynamic changes of inconstant road surface. This paper researched on self-adaptive 4WD system which is based on electronic differential of motor type: It can distribute driving torque dynamically among the driving wheels according to the vehicle driving state and road conditions, and utilize road adhesion capability to the maximum limit, improve vehicle stability and passthrough performance and reduce adverse effects on fuel economy. The research showed that 4WD system with motor-based electronic differential can be self-adaptive to vehicle driving state and road conditions and achieve best driving layout.

Jianhua, Wang, Yuncheng, Wang, Fei, Xie

Limited Slip Additive Testing and Development: New Products with Improved Thermal Stability

2007-01-198807/23/2007

Limited slip differentials, developed over 40 years ago to counter drive wheel slippage when different traction conditions exist on either side of an axle, are still widely employed by the automotive industry to improve driving control. In a limited slip differential (LSD) frictional couplings connect the axle shafts to the differential and provide the means of transmitting power to the wheels. The friction plates in the coupling may contain a variety of friction materials including metal, paper, sintered bronze, and carbon. Each one of these materials has very different frictional and wear characteristics and each one requires a different response from the gear additive package. Each plate must be durable over the course of the vehicle lifetime irrespective of the material used. As the demands on rear axles increases with the application of greater horsepower and the increasing requirements of aerodynamic engineers, the lubrication of these friction plates remains an ongoing challenge

Vettel, Paula, Lindsay, David

Traction and Clutch Effects on the Natural Frequency and Vibration Stability of Limited Slip Differential Axles

2007-01-229505/15/2007

The torsional natural frequencies of axles equipped with limited slip differential clutches depend on whether or not the tires and clutches are slipping since the effective inertia at each end of the axle is different for slipping and non-slipping conditions. Limited slip axle vibrations are typically analyzed for one tire slipping and the other not since that is the case for which the limited slip clutches are used. Vibrations often arise, however, during normal turning when both drive tires have good traction. Models for estimating the torsional natural frequencies of limited slip axles are presented for the cases of: Non-slipping clutches, neither tire slipping Non-slipping clutches, both tires slipping Non-slipping clutches, one tire slipping, one tire not slipping Slipping clutches, neither tire slipping Slipping clutches, both tires slipping Slipping clutches, one tire slipping, one tire not slipping Vibration frequencies varying from below 1 Hz to about 500 Hz are shown to arise

Cameron, T. M., Hewette, C., McCombs, T., DeGonia, D., Jao, T. C.

The Application Concept of Universal Joint to Make Limited Slip Differential, Center Differential and Clutch

2007-01-066204/16/2007

There are many types of joint that are popularly used nowadays; and the Universal joint is one of the types. However, the application of the Universal joint limits the angle of the driving axle and the driven axle not less than 160 degrees. The lower degree of this angle will require unnecessary higher input torque because the input load increases. Therefore, in this article presents the application concept of Universal joint at the angle lower than 160 degrees, such as: Limited Slip Differential, Center Differential, Viscous Coupling and Clutch.

Anantapal, Nonnwats

Axle and Manual Transmission Lubricants

J308_200703-TEST-REC (Historical)03/22/2007

This SAE Information Report was prepared by the SAE Fuels and Lubricants Technical Committee for two purposes: (a) to assist the users of automotive equipment in the selection of axle1 and manual transmission lubricants for field use, and (b) to promote a uniform practice for use by marketers of lubricants and by equipment builders in identifying and recommending these lubricants by a service designation.

Fuels and Lubricants TC 3 Driveline and Chassis Lubrication

Axle and Manual Transmission Lubricants

J308_200703 (Historical)

03/22/2007

Fuels and Lubricants TC 3 Driveline and Chassis Lubrication

Next Generation Torque Control Fluid Technology, Part II: Split-Mu Screening Test Development

2006-01-327110/16/2006

The popularity of SUVs and light trucks in North America, combined with the return to rear-wheel-drive cars globally, is significantly increasing the installation of torque control devices that improve vehicle stability and drivability. As with other driveline hardware, it is important to optimize the friction material-lubricant-hardware system to ensure that a torque control device provides consistent performance over the life of the vehicle. While there are many publications on friction tests relevant to automatic transmission fluids, the literature relating to torque control testing is not as well developed. In this paper, we will describe a split-mu vehicle test and the development of a split-mu screening test. The screening test uses the SAE#2 friction test rig and shows how results from this test align with those from actual vehicle testing.

Schenkenberger, Chris, Schiferl, Elizabeth, Garling, Gary, Baker, Mark, Huston, Michael E., Parham, Dwight, Prengaman, Chris, Rhoads, Gabe, Vermilya, Denise

All-Wheel Driveline Mechatronic Systems: Principles of Wheel Power Management

2006-01-058004/03/2006

All-wheel driveline systems with electronic torque control on each and all wheels, torque vectoring and torque management devices, hybrid electro-mechanical systems, and individual electro (hydraulic) motors in the wheels have been gaining a bigger interest in the industry for recent years. The majority of automotive applications are in vehicle stability control that is performed by controlling the vehicle yaw moment. Some devices also improve vehicle traction performance. The proposed paper develops a methodology that includes the key-principles in all-wheel driveline systems design and is based on the wheel power management as a broader analytical approach. The proposed principles relate to the optimization of power distributions to the drive wheels in both rectilinear and curvilinear vehicle motion. Inverse dynamics is the basis for the developed methodology. Combinations of optimal power distributions at the drive wheels and proactive estimation of the road conditions (friction

Vantsevich, Vladimir V.

Pyrolytic Carbon Wet Friction Materials

2005-01-358811/01/2005

Carbon based friction materials continue to gain increasing acceptance in many friction applications. One unique class of carbon based friction materials is Chemical Vapor Deposited carbon fabric (CVD Fabric™) Since 1991, CVD Fabric™ has been used in production automotive wet friction applications including limited slip differentials and heavy and medium duty truck transmission synchronizers. It offers stable friction levels, low wear rates and is readily wetted by transmission oils. Because CVD Fabric does not soften with temperature and is unaffected by solvents, this high energy absorption, high abuse tolerant material may provide significant performance advantages in off-highway wet brake and clutch applications. This paper will explore the Physical, mechanical and tribological properties of CVD Fabric wet friction materials.

Awasthi, S., Taccini, G.

Driveline Layout Influence on Four Wheel Drive Dynamics

2004-01-086003/08/2004

The paper presents the research activity managed to investigate the dynamics of a 4WD vehicle equipped considering drivelines with different layout. The procedure developed required to conceive an on purpose simulator to compare performance through virtual experimentation. Drivelines mechanical main characteristics and performance increasing due to control strategy were evaluated. Preliminary road test were performed with a single driveline layout, to evaluate simulation reliability and limits. The paper presents the 4WD vehicle simulator, the main equations applied to model open, torque sensing and limited slip differentials, some preliminary road test results showing torque sensing driveline performance.

Danesin, Davide, Girardin, Christian, Sorniotti, Aldo, Morgando, Andrea, Velardocchia, Mauro

All-Wheel Drive Vehicle Energy Efficiency Evaluation

2004-01-086403/08/2004

All-wheel drive (AWD) vehicle performance considerably depends not only on total power amount needed for the vehicle motion in the given road/off-road conditions but also on the total power distribution among the drive wheels. In turn, this distribution is largely determined by the driveline system and its mechanisms installed in power dividing units. They are interwheel, interaxle reduction gears, and transfer cases. The paper presents analytical methods to evaluate the energy and, accordingly, fuel efficiency of vehicles with any arbitrary number of the drive wheels. The methods are based on vehicle power balance equations analysis and give formulas that functionally link the wheel circumferential forces with slip coefficients and other forces acting onto an AWD vehicle. The proposed methods take into consideration operational modes of vehicles that are tractive mode, load transportation, or a combination of both. The methods are applicable to any type of AWD vehicles including

Vantsevich, Vladimir V.

Advances in Additive Technology for Limited Slip Axles – Part I Friction Test Development

2003-01-323410/27/2003

Limited slip differentials have been used for many years in the automotive industry to improve driving control and reduce chatter and vibrations from the rear axle. The choice of proper lubricant is essential to quiet and smooth operation. Special additives are available to modify the frictional response in the coupling to eliminate stick-slip problems. In recent years, there has been a trend in the US toward higher axle sump temperatures. Therefore, new limited slip additives are needed with better thermal stability and frictional performance. In this paper, we will present the results of the development of a bench test to measure the friction performance of limited slip lubricants.

Vettel, Paula, Bielik, Peter

Development of a Fuel Efficient Multipurpose 75W-90 Gear Lubricant

2003-01-199210/27/2003

Automotive gear oil development has expanded beyond the historical requirements of emphasizing wear protection to encompass modern needs for fuel economy and limited slip frictional properties. This paper describes the development process of a new generation, fuel efficient gear lubricant for use in light duty vehicles. A systematic formulation approach was used, encompassing fluid viscometrics and additive optimization. Performance testing in both laboratory and vehicle tests is described. Though standard GL-5 tests were used to confirm oxidation, wear and corrosion performance, emphasis is given to those methods used for optimizing fuel economy.

Bjornen, Kay K., Chambers, Harold, DeGonia, David

Linear Back-Drive Differentials

TBMG-2935902/01/2003

Linear back-drive differentials have been proposed as alternatives to conventional gear differentials for applications in which there is only limited rotational motion (e.g., oscillation). The finite nature of the rotation makes it possible to optimize a linear back-drive differential in ways that would not be possible for gear differentials or other differentials that are required to be capable of unlimited rotation. As a result, relative to gear differentials, linear back-drive differentials could be more compact and less massive, could contain fewer complex parts, and could be less sensitive to variations in the viscosities of lubricants.

2000 HP Tractor-Trailer for the 21st Century

2002-01-314111/18/2002

This paper presents the conceptual design of a high-power, high-speed tractor-trailer for severe duty applications. Design of the tractor-trailer introduces several new concepts, including the general vehicle architecture, a new electrical transmission system and a new electric tandem axle. The vehicle architecture consists of a low drag cab concept with a fully integrated turbo-generator power source, an exhaust gas electric decontamination system and auxiliaries. The electric transmission introduces a new combination of electrical machines and power electronics designed to perform under maximum load with minimum dimension, weight and price. The electric tandem axle is a new concept of an all-wheel steering independent suspension with virtual electromagnetic differential.

Cantemir, Codrin-Gruie, Hubert, Chris, Rizzoni, Giorgio, Ursescu, Gabriel

Fuel Economy Improvement Through Frictional Loss Reduction in Light Duty Truck Rear Axle

2002-01-282110/21/2002

In an effort to improve fuel economy for light duty trucks, an initiative was undertaken to reduce frictional losses in rear axle through use of low friction lubricants and novel surface finish on gears while maintaining durability. This paper describes the effect of rear axle lubricants on fuel economy. A laboratory rig was set up using a full size pick-up truck rear axle to measure axle efficiency and lubricant temperature with various SAE 75W-90 and SAE 75W-140 viscosity grade lubricants. Traction coefficients of lubricants were also measured at various temperatures using a laboratory ball and disk contact geometry. An improvement in axle efficiency up to 4.3% was observed over current Ford factory fill SAE 75W-140 lubricant depending on speed, torque and the type of lubricant used. The temperature of the lubricants was also lower than that with the current factory fill. This is important for maintaining bearing life and overall durability of the rear axle. Chassis roll fuel economy

Gangopadhyay, Arup, Asaro, Sam, Schroder, Michael, Jensen, Ron, Sorab, Jagadish

Improved Differential Function for Avoiding Slippage of Motor Vehicles in a Muddy Trench

2002-01-098803/04/2002

Vehicles such as trucks, buses and cars often get struck up in muddy trenches or in snow with one of wheels in the trench and the other on level ground. With an open differential, driver's effort to pull the vehicle out normally ends up with one wheel, which is rotating still going deeper into the trench. Until now Limited Slip Differentials (LSD), Locked Differentials and Viscous Coupling etc. have been used to overcome this difficulty but with limited success. Incorporating logic devices has developed a novel solution to this problem and the traction on the required wheel is achieved automatically. The system works independently of the conventional brakes.

Gill, S. S., Kalsi, N. S., Singh, Balraj, Singh, Nirmal, Singh, Neetu

Development of Active-Traction Control System

2000-01-163605/01/2000

Active-TRAC (A-TRAC) is the system for off-road 4WD vehicles. This system consists of independent four wheel brake control system and engine torque control system. This system applies the brake to any spinning wheel, and sends torque to the other wheels with grip. Therefore, the vehicle gets strong LSD(Limited Slip Differential) effect, and it has the same traction performance as a center and rear differential locked vehicle. Because the vehicle with A-TRAC does not have a differential locking mechanism, it no longer has the phenomenon of tight corner braking, and it frees a driver from operating the differential locking system. Therefore anyone can easily enjoy off-road driving with A-TRAC.

Hosomi, Kazushi, Nagae, Akira, Yamamoto, Shinsuke, Takahira, Yosuke, Koizumi, Masamichi, Ishikawa, Tosimi

New Traction-Optimized Front Axle Limited-Slip Differential for AWD All-Terrain-Vehicle

2000-01-115503/06/2000

An advancement in All-Terrain-Vehicle (ATV) traction control has entered the market place with the debut of the 1999 Bombardier Traxter. The basis for this is the progressive front axle limited-slip differential. The Visco Lok‚ differential provides a speed-sensing progressive traction-optimized characteristic for maximum off-road performance. This paper includes an overview of the vehicle driveline system, functional characteristics of the differential, and torque transfer requirements.

Barlage, John A., Bolton, Jerry L.

Automotive Driveline System Engineering

2000-01-143901/15/2000

The trend in the automotive industry to include niche products with 4WD results in high development and investment cost for the manufacturer due to major changes to the platform and new technology. System suppliers for 4WD drivelines can help to reduce these costs significantly by developing “standardised” driveline concepts and taking on the responsibility for the layout, design, manufacture, assembly and validation of the system. A range of traction and handling improving limited slip devices as well as halfshafts and propshafts are available. They need to be integrated into the driveline system which then is being optimised with regard to system function, endurance and NVH.

Trommer, Jörg, Exner, Wolfgang

Numerical Design of a Low Mass Differential Housing

1999-01-074103/01/1999

Lawrence Technological University's 1998 SAE Formula car needed a high performance differential assembly. The performance requirements of a competitive SAE Formula car differential are as follows: Torque sensing capabilities Perfect reliability High strength Low mass Ability to withstand inertia and shock loading Small package Leak proof housing Ability to support numerous components With these requirements in mind an existing differential was selected with the capability for torque sensing. This differential lacked the desired low mass, support, internal drive splines, and proper gearing protection. The differential was re-engineered to remedy the deficiencies. The internal gearing from the selected differential was used in an improved casing. This casing and it's position in the car, reduce the number of side-specific parts required as well as improving the performance. The new design significantly reduces the size and mass of the assembly. This design improves reliability while

Jawad, Badih A., Fowler, John G., Brandow, Leon M., Trimboli, Brian A.

Redesign of a Differential Housing for a Formula Car (FSAE)

98307711/16/1998

A unique differential assembly was needed for the Lawrence Technological University (LTU) SAE Formula race car. Specifically, a differential was required that had torque sensing capabilities, perfect reliability, high strength, light weight, the ability to withstand inertia and shock loading, a small package, no leaks, the ability to support numerous components. In that regard, an existing differential was selected that had the torque sensing capabilities, but had deficiencies that needed to be fixed. Those deficiencies included the following: Differential unit was over 4 kg unmounted, with no housing. This was considered too heavy, when housed properly. Bearing surface was provided on only one end of the carrier. This design provides insufficient bearing surface to support either the differential housing or half-shafts The internal drive splines integral to the case are not optimized for a perpendicular drive/axle arrangement, such as, a chain drive. Differential unit is an open cased

Jawad, Badih A., Fowler, John G.

An All Wheel Drive System Utilizing Twin Hydraulic Couplings with Gerodisc System

97323511/17/1997

Hydraulically actuated, friction disc type couplings are capable of being utilized as direct drive limited slip devices for use on auxiliary drive axles. These couplings can be excited to function at wheel speed Δn levels due to their high torque transfer density and high torque transfer capacity. The utilization of these hydraulic couplings eliminates the need for torque multiplication through speed reduction. The common differential element is replaced by two independent, but communicating couplings to facilitate direct drive of the wheels on the auxiliary axle. The arrangement described in this paper provides a built in limited slip differential (LSD) effect as well as a simple and powerful all wheel drive (AWD) system. This paper will compare the performances of such systems with classic architectures under various driving conditions.

Okcuoglu, Murat

Actuating Vehicle Systems and Unified Limited Slip Differentials

97275109/08/1997

A peculiarity of all-wheel drive off-highway vehicles is that their running abilities (cross-country mobility, tractive and velocity properties, turnability and the like) depend not only on total traction effort but also on its distribution between driving wheels. The latter is in great measure determined by actuating vehicle system and characteristics of the mechanisms installed in power dividing transmission units, i.e. in interwheel, interaxle reduction gears, and transfer cases. The characteristics of locking performance of these mechanisms regulate the circumferential force distribution between driving wheels and, respectively, a vehicle's performance indicators. Such mechanisms have been created and are being created in a multitude. The classification of power dividing mechanisms and system is given. They provide a high level of the traction performance of all-wheel drive off-highway vehicles and agricultural tractors, in particular. The article features a statistical analysis of

Vantsevich, V. V.

A Descriptive Analysis of Gerodisc Type Limited Slip Differentials and All Wheel Drive Couplings

95264211/01/1995

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.

Okcuoglu, Murat N.

A Building Block Approach for Understanding Four Wheel Drive Systems: Past-Present-Future

95264311/01/1995

This paper describes a building block approach for understanding the past, present and future four wheel drive systems. The emphasis will be on light trucks and sport utility vehicles. It will describe the advantages of four wheel drive and how it improves performance and safety. The building block approach is a tool for categorizing the basic systems in the market. Systems are separated into main component areas and are rated for the effect they have on the overall performance and safety. This paper can be used as a means for understanding a very complex 4x4 market.

Williams, Randolph C., Socin, Richard J., Varma, Sanjeev K.

Passenger Car 4WD-Systems for Light Trucks?

95264711/01/1995

Four-wheel-drive technology for passenger cars shows a remarkable variety of solutions, whereas in off-road-vehicles usually only systems are used which are well known since decades. With passenger cars, good traction is only one of several criteria, of which ease of operation is certainly a must. Effects on driving behavior and safety factors such as braking stability and ABS-compatibility become more and more significant. Since the average owner of an off-road-vehicle uses his car mainly in normal traffic situations, the question arises, why the modern 4WD-systems of passenger cars are not applied to off-road-vehicles or light trucks. This question will be discussed in the light of the typical torque distribution of these systems, the traction performance, and the driving behavior resulting from it.

Lanzer, Heribert

Oversteer/Understeer Characteristics of a Locked Differential

94248512/01/1994

The type of differential used in a vehicle has an important and often-neglected effect on handling performance. This is particularly important in racing applications, such as in IndyCar racing, in which the type of differential chosen depends on the course being raced (superspeedway ovals, short ovals, temporary street courses and permanent road courses). In the present work, we examine the effect of a locked rear differential on oversteer/understeer behavior. Using a linear tire model, it is shown that employing a locked differential adds a constant understeer offset to the steering wheel angle (SWA) -v- lateral acceleration vehicle signature. A computer simulation of steady-state cornering behavior showed that the actual effect is much more complicated, and is strongly influenced by static weight distribution, front/rear roll couple distribution, available traction and the radius of the turn being negotiated. Testing performed on a Formula SAE racing car was used to verify the

Hopkins, Patrick, Metz, L. Daniel

Advanced Development of Self-Controlled Torque Sensitive Limited-Slip Differential by Means of Helical Gears

94073303/01/1994

This paper compares and contrasts several types of torque-sensitive limited slip differential designs while focusing on the self-controlled helical gear differential. Cone-and plate-type locking differentials in common use today offer a low production cost but tend to change locking characteristics as they wear and influence vehicle handling and braking. Current worm gear type limited slip differentials present a disadvantage in that they have a limited range of available locking ratios as a function of cost and also present long-term durability issues. Thus, attention has turned in recent years to the self-controlled helical gear approach. This method offers a wide range of locking ratios thus making it possible to tune the performance of the differential to match virtually any vehicle. Applications involving use of this design as a rear wheel differential and as a center differential are described. Uneven distribution of torque is often desirable in a center differential and the

Rohregger, W., Amborn, P., Kaufmann, O. A.

Analysis of Traction Control Systems Augmented by Limited Slip Differentials

94083103/01/1994

Traction Control Systems (TCS's) are becoming increasingly present in today's automobiles. These systems strive to improve the traction and stability characteristics of the vehicle by actively controlling wheel slip. Limited Slip Differentials (LSD's) offer a passive method (no control system required) of improving the traction and stability of the vehicle, by appropriately proportioning wheel torque. This paper will investigate the compatibility of these two approaches by demonstrating the function and performance of various LSD/TCS combinations.

Holzwarth, Robert K., May, Kenneth A.

The Effect of a Viscous Coupling Used as a Front-Wheel Drive Limited-Slip Differential on Vehicle Traction and Handling

94087503/01/1994

The viscous coupling is known mainly as a driveline component in four wheel drive vehicles. Developments in recent years, however, point toward the probability that this device will become a major player in mainstream front-wheel drive application. Production applications in European and Japanese front-wheel drive cars have demonstrated that viscous couplings provide substantial improvements not only in traction on slippery surfaces but also in handling and stability even under normal driving conditions. This paper presents a series of proving ground tests which investigate the effects of a viscous coupling in a front-wheel drive vehicle on traction and handling. Testing demonstrates substantial traction improvements while only slightly influencing steering torque. Factors affecting this steering torque in front -wheel drive vehicles during straight line driving are described. Key vehicle design parameters are identified which greatly influence the compatibility of limited-slip

Huchtkötter, H., Taureg, H.

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