Browse Topic: Hydromechanical transmissions

Items (104)

Hydrodynamic Drives Terminology

J641_201912 (Current)12/02/2019

Since the torque converter and fluid coupling are commonly used components of automatic transmissions in industry, the SAE appointed a committee to standardize terminology, test procedure, data recording, design symbols, and so forth, in this field. The following committee recommendations will facilitate a clear understanding for engineering discussions, comparisons, and the preparation of technical papers. The recommended usages represent the predominant practice or the acceptable practice. Where agreement is not complete, alternates have been included for clarification. EXAMPLE: Two systems of blade angle designations are described. Consequently, when a blade angle is specified, the system should be designated. This SAE Recommended Practice deals only with the physical parts and dimensions and does not attempt to standardize the design considerations, such as the actual fluid flow angle resulting from the physical blade shape.

Automatic Transmission and Transaxle Committee

Automatic Transmissions - Schematic Diagrams

J647_201911 (Current)11/19/2019

The following schematic diagrams reflect various methods of illustrating automotive transmission arrangements. These have been developed to facilitate a clear understanding of the functional interrelations of the gearing, clutches, hydrodynamic drive unit, and other transmission components. Two variations of transmission diagrams are used: in neutral (clutches not applied), and in gear. For illustrative purposes, some typical transmissions are shown.

Automatic Transmission and Transaxle Committee

Domestic Performance Torque Converter Manufacturing

J2440_201910 (Current)10/09/2019

The scope of this SAE Draft Technical Report is to establish dimensional standards for high-performance domestic torque converter manufacturers. Many torque converter manufacturers build converters to their own standards. Some of these standards may be outside of the specifications that define a quality performance torque converter.

Motor Vehicle Council

Automotive Transmission Terminology

J645_201708 (Historical)08/25/2017

The following listed definitions are intended to establish terminology and criteria for describing the various kinds of automotive transmissions. A specific arrangement may be described by a combination of several of these definitions.

Automatic Transmission and Transaxle Committee

Reduction in Dynamicl of the Hydromechanical Transmission on the Wheeled Chassis

2015-01-278909/29/2015

The article has represented the results of researching multiple wheeled chassis (MWC) hydromechanical transmission dynamic loading. On the basis of comparing frequencies of dynamic moment resonant fluctuations and frequencies of diesel engine indignation, the hypothesis about subharmonic resonance realization in the mechanical system having strong nonlinear elastic characteristic is offered and grounded. A method of tuning out undesirable fluctuations which form dynamic loading to take subharmonic resonant modes out of the engine rpm speed working range is developed. On the basis of the results obtained, some technical decisions are suggested which allow decreasing transmission dynamic load and a new type damper designs of different models are developed. It allows taking resonant modes out of the engine rpm speed working range, thus creating the conditions of increasing transmission elements durability.

Taratorkin, Igor, Taratorkin, Alexander, Derzhanskii, Viktor

Passenger Car and Light Truck Automatic Transmission and Automatic Transaxle Test Code

J651_201506 (Current)06/30/2015

The extent of test conditions on the dynamometer must be sufficient to determine the efficiency characteristics corresponding to the following range of vehicle operations in all gear ratios with locked torque converters (open converter can also be done where appropriate and noted). a Efficiency versus output speed versus input torque b Torque ratio versus output speed c Input speed versus output speed d Output torque versus output speed e Parasitic loss versus input speed (spin losses) f Cooler flow g Output torque bias (front wheel drive transaxles)

Automatic Transmission and Transaxle Committee

Quasi-Continuously-Variable Transmission Provides Hydraulic Regenerative Braking for Passenger Cars, Trucks, and Buses

2014-01-171704/01/2014

A hydro-mechanical transmission is described that approximates the “gearing” performance of a continuously variable transmission and incorporates all functions required for hydraulic regenerative braking. Other characteristics such as efficiency, noise, and responsiveness, match or exceed that of present day conventional automatic transmissions. Performance and physical sizing are shown for passenger vehicle, bus and truck transmissions.

A Dual Clutch Torque Converter for Dual Input Shaft Transmissions

2013-01-023204/08/2013

This paper presents an alternative launch device for layshaft dual clutch transmissions (DCT's). The launch device incorporates a hydrodynamic torque converter, a lockup clutch with controlled slip capability and two wet multi-plate clutches to engage the input shafts of the transmission. The device is intended to overcome the deficiencies associated with using conventional dry or wet launch clutches in DCT's, such as limited torque capacity at vehicle launch, clutch thermal capacity and cooling, launch shudder, lubricant quality and requirement for interval oil changes. The alternative device enhances drive quality and performance at vehicle launch and adds the capability of controlled capacity slip to attenuate gear rattle without early downshifting. Parasitic torque loss will increase but is shown not to drastically influence fuel consumption compared to a dry clutch system, however synchronizer engagement can become a concern at cold operating temperatures. The performance of the

Robinette, Darrell, Skrzycke, Ted

Hydrodynamic Drives Terminology

J641_201206 (Historical)06/04/2012

Since the torque converter and fluid coupling are commonly used components of automatic transmissions in industry, the SAE appointed a committee to standardize terminology, test procedure, data recording, design symbols, and so forth, in this field. The following committee recommendations will facilitate a clear understanding for engineering discussions, comparisons, and the preparation of technical papers. The recommended usages represent the predominant practice or the acceptable practice. Where agreement is not complete, alternates have been included for clarification. This SAE Recommended Practice deals only with the physical parts and dimensions and does not attempt to standardize the design considerations, such as the actual fluid flow angle resulting from the physical blade shape.

Automatic Transmission and Transaxle Committee

Symbols for Hydrodynamic Drives

J640_201107 (Current)

07/08/2011

The following system of symbols is recommended for use in technical papers and engineering reports dealing with hydrodynamic drives.

Automatic Transmission and Transaxle Committee

Torque Converter Clutch Optimization: Improving Fuel Economy and Reducing Noise and Vibration

2011-01-014604/12/2011

The torque converter and torque converter clutch are critical devices governing overall power transfer efficiency in automatic transmission powertrains. With calibrations becoming more aggressive to meet increasing fuel economy standards, the torque converter clutch is being applied over a wider range of driving conditions. At low engine speed and high engine torque, noise and vibration concerns originating from the driveline, powertrain or vehicle structure can supersede aggressive torque converter clutch scheduling. Understanding the torsional characteristics of the torque converter clutch and its interaction with the drivetrain can lead to a more robust design, operation in regions otherwise restricted by noise and vibration, and potential fuel economy improvement. The objective of this paper is to present a generalized integration summary for torque converter clutches (TCC) to enable aggressive apply at high engine torques and engine speeds below 1500 rpm without adversely

Robinette, Darrell, Grimmer, Michael, Horgan, Jeremy, Kennell, Jevon, Vykydal, Richard

A Power-Split Hybrid Hydraulic Vehicle Transmission Modeling and Comparative Analysis

2010-01-201010/05/2010

Recent innovative drives in hydraulics could introduce very competitive hybrid hydraulic vehicles (HHV). These drives has been considered and analyzed only in the serial HHV architecture. The series-parallel transmission architecture, also called power-split or e-CVT is highlighted as the most popular concept for full (strong) hybrid electric vehicles (HEV). The examples are one-mode power-split in Toyota Prius and two-mode (compound) power-split in GM-Allison EVT. Ambitions to make the hybrid hydraulic power trains better and more efficient would certainly require deeper analysis of more complex power-split (series-parallel) HHV transmission structures and related optimal controls. This paper presents bond graph based mathematical model of kinematics of a one-mode and a two-mode power-split hybrid hydraulic vehicle transmissions which are based on their hybrid electrical counterpart. Such models serve as a basis for the analysis of the steady-state behavior of two representative power

Automatic Transmissions - Schematic Diagrams

J647_201004 (Historical)

04/23/2010

The following schematic diagrams reflect various methods of illustrating automotive transmission arrangements. These have been developed to facilitate a clear understanding of the functional interrelations of the gearing, clutches, hydrodynamic drive unit, and other transmission components. Two variations of transmission diagrams are used: in neutral (clutches not applied) and in gear. For illustrative purposes, some typical transmissions are shown.

Automatic Transmission and Transaxle Committee

Target Volume Based Shift Controls with High Flow PWM Solenoids

2010-01-036904/12/2010

The Chrysler Ultradrive four-speed transaxle 41TE was the first production transmission to pioneer fully adaptive direct clutch-to-clutch electronic controls without overrunning clutches. "Single stage" high flow PWM solenoids have been used for transmission control since 1989 and still being used in the later-developed 545RFE and 62TE transmissions. The proposed target volume-based shift control method allows the usage of flow-based control device such as PWM solenoids to implement torque-based control strategy. Vehicle test results with this new method have shown excellent shift quality and improved system consistency.

Chen, Gang, Dourra, Hussein

Automotive Transmission Terminology

J645_200903 (Historical)

03/03/2009

The following listed definitions are intended to establish terminology and criteria for describing the various kinds of automotive transmissions. A specific arrangement may be described by a combination of several of these definitions.

Automatic Transmission and Transaxle Committee

New Generation Hydraulic-Mechanical Transmission with Lock-up Mechanisms and Automatic Start Clutch

2008-32-004009/09/2008

New Generation Advanced Hydraulic-Mechanical Transmission (A-HMT) with the Lock-Up mechanism and the automatic start clutch mechanism was developed. In the lock-up mechanism, an electronic control in conjunction with transmission control was adopted using oil temperature, throttle opening, and input / output rotation ratio as parameter to reduce a rotational energy change of input and output axis caused by the volumetric efficiency of A-HMT. In the automatic start clutch, the load sensing function, damper function, and cooling function by replacing the simple hydraulic mechanism are equipped. By these solutions, the transmission efficiency has enhanced approximately 10% compared with former A-HMT, and excellent starting performance and smooth transmission performance have achieved.

Yoshida, Yoshihiro, Yakigaya, Nobuyuki, Nakamura, Kazuhiko, Takeuchi, Kazuhiro, Nakano, Kenichi, Usukura, Yasutaka

A numerical model for the simulation of Diesel/CVT power split transmission

2007-24-013709/16/2007

This paper presents a steady-state numerical model of a power split hydro-mechanical input-coupled transmission for off-road vehicles. In this kind of transmissions the combustion engine is connected to a planetary and to a hydrostatic unit. Depending on vehicle speed and power request, the power is transmitted either hydrostatically or mechanically, or in both ways. The performance of the Diesel engine has been simulated in a simple manner by means of a look-up table, based on the specific fuel consumption map; a similar approach has been adopted for the efficiency of the hydrostatic units. The code is able to predict the overall efficiency of the powertrain, while highlighting the contributions of the hydrostatic path, of the mechanical path and of the engine. The results show how the code can be used both for locating the optimum operating point, as a function of the specific duty, and for analysing different configurations of the transmission.

Casoli, P., Vacca, A., Berta, G.L., Meleti, S., Vescovini, M.

Analysis of a Hybrid Multi-Mode Hydromechanical Transmission

2007-01-145504/16/2007

A multi-mode hybrid hydromechanical transmission (HMT) with infinite variability is designed to meet the power transmission needs of medium duty on- and off-road vehicles. A hydraulic pump-motor assembly provides output speed and torque variability in an input coupled split power configuration. Dual planetary arrangements with two multiplate clutches allow multi-mode ratio change and combination of power from the mechanical and variable branches of the power path. Hydraulic accumulators offer hydraulic power assist during launch conditions and storage of reclaimed energy during braking events. Transmission kinematic, force and power flow analyses will be developed for the HMT and analyzed for suitability in a bus application. The resulting benefits and areas for improvement will be discussed.

Fussner, Doug, Wendel, Glenn, Wray, Chris

New Transmission Technologies on Gear Requirements for Global Powder Metal Industry

2006-01-039604/03/2006

Auto companies are transforming four and five speed to six and seven speed transmissions. Manual transmissions are being converted to dual clutch design and it is anticipated in North America true manual transmissions will be extinct. Continuous variable transmission although making slow inroads is a threat to PM. Hybrid vehicles using battery powered electric motors and fuel cell powered electric motors pose a continuing challenge to PM. This presentation will cover the new technologies and their impact globally on automotive transmission and opportunities for PM.

Narasimhan, Kalathur S., Boreczky, Eric

New Technology for the Management and Distribution of Torque in Modern Automotive Drivetrains

2005-01-063004/11/2005

Hydraulic, mechanical, and electro-magnetic technologies have been the primary means for torque management in today's drivetrains. Recent advances in electronic controls have provided even greater performance benefits for these base technologies. These facts coupled with an extended period of design and development for these drivetrain systems make the introduction of a new technology very challenging. However, recent developments at Borg Warner's Powertrain Technical Center have shown that a new technology, hydro-mechanical technology, may hold great promise in solving some of the fundamental problems and limitations of today's torque management technologies. This paper illustrates drivetrain applications where hydro-mechanical technology offers new and improved performance benefits for some of drivetrain's oldest problems. The opportunity to bring a new technology to the market in drivetrains also provides a new opportunity for powdered metallurgy (P/M) content in same. As a leader

Kelley, William R.

The Fundamental Aspects of the Structural Theory of Multispeed Transmissions Control

2005-01-159804/11/2005

The first level task among the tasks of analysis and synthesis of the control systems (CS) for multispeed transmissions (MT) is the organization of speed shifts process. The method of synthesis of electrohydraulic schemes of mechatronic CS, that is based on the theory of discrete logical devices is worked out by us (see SAE Tech. Pap. Ser. 2003-01-0319). It was shown, that there is a close relation between the structures of CS and MT. Therefore it is necessary to know the properties of MT as the object of control. The analysis of such properties is the subject of this paper. It is shown that the relation between CS and MT at the level of their structures may be described quite fully with help of three basic parameters of MT kinematics schemes: the number of freedom degrees, the number of control elements (CE), the number of speeds. The concept of generalized CS and MT is introduced. This concept permits to give quantitative evaluation of their multiplicity, to formulate and to decide

Power Split Transmissions Versus Hydrostatic Multiple Motor Concepts - A Comparative Analysis

2004-01-267610/26/2004

The aim of the presented study was to analyze the potentials of two different drive line concepts. The comparison is made for a simple Power Split Drive and a Hydrostatic Two-motor Transmission with a disconnectable hydromotor. The main focus is put on the achievable overall efficiency of both alternatives. The system complexity of the two compared transmissions is very different. The analysis therefore also looks towards this matter and further makes an assessment of the different control requirements.

Krauss, Alexander, Ivantysynova, Monika

The Synthesis Method of Electro-Hydraulic Schemes of Mechatronic Control Systems for Hydromechanical Transmissions

2003-01-031903/03/2003

The multispeed hydromechanical transmissions (HMT) belong to the most complicated automotive components. For many years the theory and the methods of the HMT analysis and synthesis were developed. For example, the “Lever Analogy” method is known (see SAE Pub. N810102 (1981). New computer-aided methods allow synthesis HMT kinematic schemes with preset gear ratio ranges. The most important element of any modern HMT is the mechatronic control system (MCS), that practically gives to it the properties of continuously variable transmission. The base of MCS is the electro-hydraulic part, that defines its liveness and safety. Nevertheless, the analysis shows that apparently there are no generally accepted methods of their construction. In this paper the analytical method of synthesising HMT electro-hydraulic control system is proposed. It is based on the theory of analysis and synthesis of discrete logical devices which is well known in technical cybernetics.

Krasnevski, Leonid

Concepts and Development Trends for Efficiency Improvement of Hydrostatics in Mobile Applications

2002-01-142203/19/2002

In mobile vehicles such as earth moving machines, agriculture machines, forest machines, industrial and mining lifters there is a demand for sophisticated performance. Since the requirements on productivity are very high for mobile machinery, high output capacity combined with high overall efficiency over a wide velocity range is therefore of great importance. A traditional solution for drive train in mobile machinery is to use a hydrodynamic transmission (torque converter) in series with a multi-speed shiftable gearbox. For heavy machines, engine power above 150 kW, torque converters have been used exclusively until a few years ago. However, the development of hydrostatic drive concepts and microprocessor control have made it possible to be competitive with converter drives. Joining pumps, motors and mechanical gears in smart concepts, so called power split transmissions, has make it possible to keep prescribed output power and velocity range without the need of sophisticated power

Rydberg, Karl-Erik

The Universal Control and Protection Hydraulic Automaton for Hydromechanical Transmissions

2001-01-087903/05/2001

Modern hydromechanical transmissions are equipped with electronic-hydraulic (mechatronic) control systems having much more functional capabilities compared to classic hydraulic systems. However, automatic hydraulic systems are widely used not only as the basic transmissions' control device and a mechanical part of mechatronic systems but also as an important facility providing reliability and safety of such systems. At the same time such an application has quite a number of restrictions, especially for transmissions with a great number of gearstages. One of the main reasons is the inability to control more than 3 or 4 stages of gears while using the vehicle's speed as a control parameter. It deals with the parabolic characteristic of the output pressure of centrifugal governor used as the vehicle speed sensor. This restriction can be eliminated by using a hydraulic detector of torque converter's turbine (i.e. input shaft of gearbox) speed. The paper considers the operating principles

Krasnevski, L., Vysotski, M., Boikov, V.

Advanced Hydro-Mechanical Transmission with High-Durability for Small Utility Vehicles

2001-01-087603/05/2001

The new automatic transmission, A-HMT (Advanced Hydro-Mechanical Transmission) has been developed for the Honda ATV (All Terrain Vehicle), which is for wide applications such as utility, recreation, etc. The A-HMT system features high performance, durability and reliability attained by improving the structures from the original hydro-mechanical automatic transmission used for the scooter called “Juno”, which Honda had produced many years ago, working on the same principle. In addition to it, by applying the electronic control system, the highly responsive driveability that suits the requirements of ATV's has been realized. The A-HMT is installed in the new 500 cm3 ATV, FOURTRAX FOREMAN RUBICON, which has been introduced in the USA market since June 2000.

Hayashi, Tsutomu, Saito, Mitsuru, Yoshida, Yoshihiro, Nanri, Takehiko

Hydrodynamic Drive Test Code

J643_200005 (Historical)05/16/2000

The range of test conditions on the dynamometer shall be sufficient to determine the primary operating characteristics corresponding to the full range of vehicle operations. The characteristics to be determined are: a. Torque ratio versus speed ratio and output speed b. Input speed versus speed ratio and output speed c. Efficiency versus speed ratio and output speed d. Capacity factor versus speed ratio and output speed e. Input torque versus input speed

Automatic Transmission and Transaxle Committee

Hydrodynamic Drives Terminology

J641_200003 (Historical)03/10/2000

Since the torque converter and fluid coupling have become commonly used components of automatic transmissions in industry, the SAE appointed a committee to standardize terminology, test procedure, data recording, design symbols, and so forth, in this field. The following committee recommendations will facilitate a clear understanding for engineering discussions, comparisons, and the preparation of technical papers. The recommended usages represent the predominant practice or the acceptable practice. Where agreement is not complete, alternates have been included for clarification. Example - Two systems of blade angle designations are described. Consequently when a blade angle is specified, the system should be designated. This SAE Recommended Practice deals only with the physical parts and dimensions and does not attempt to standardize the design considerations, such as the actual fluid flow angle resulting from the physical blade shape.

Automatic Transmission and Transaxle Committee

Symbols for Hydrodynamic Drives

J640_200003 (Historical)03/10/2000

The following system of symbols is recommended for use in technical papers and engineering reports dealing with hydrodynamic drives.

Automatic Transmission and Transaxle Committee

The Safety of Mechatronic Control Systems for Hydromechanical Transmissions

1999-01-104903/01/1999

Modern vehicles have a number of safety systems, main of which are basic control systems - steering and braking systems. Requirements to these systems, defined by the vehicles design safety, are regulated by the system of the international and national standards and rules. Mechatronic control systems of the hydromechanical transmissions pertain to the “yongest” automotive systems, and questions dealing with their safety don't have yet the complete theoretical and normative base. The connection between these mechatronic systems safety and their structure is investigated in this paper. The method of the safety analysis with help of the “refusal graphs” is proposed, which permits to bring out and to eliminate the possibility of the dangerous refusals capable to create the crash situations during automobile motion.

Krasnevski, L., Vysotski, M., Boikov, V.

Simulation of a Continuously Variable Power Split Transmission

1999-01-006203/01/1999

Continuously variable transmissions promise to improve the performance and drivability of vehicles. The design and implementation of continuously variable transmissions for medium or large displacement (power) engines have been hampered by the power limitations of the belts. A continuously variable transmission with a power split design (CVPST) has been developed to minimize the loading on the belt while providing for increased power transfer compared to existing designs. To aid in the design and development of this CVPST, a simulator program has been developed. The simulator can be used to optimize the CVPST and to compare with other transmissions. Finally, an optimized CVPST design is presented.

Lu, Zhijian, Thompson, Gregory J., Mucino, Victor H., Smith, James E.

Hydrostatic Drives in Heavy Mobile Machinery–New Concepts and Development Trends

98198909/14/1998

The use of hydrostatic transmission as vehicle drives is primarily motivated by its large range of continuously variable speed, high maneuverability and a possibility to increase the overall efficiency. Consequently an optimally designed system can provide low fuel consumption and thereby low exhaust gas emission. Modern technology involving electro-hydraulic systems, microprocessor control and control theory makes it easier to utilize the advantage of these properties than using traditional hydro-mechanical control. The requirements on productivity are very high for mobile machinery. High output capacity and a wide velocity range are therefore of great importance. To meet these requirements an ordinary hydrostatic transmission is generally used with a mechanical gearbox connected in series. The main drawback in this concept is the high cost in using a gearbox, which can switch gear ratios without jerks and other disturbances in speed and torque transmission. By joining pumps, motors

Rydberg, Karl-Erik

A “Back-to-Back” Comparison of Currently Available Hydromechanical Transmissions – Utilising Boeing Easy 5™ Mathematical Modelling with the Ricardo Powertrain Library

98198709/14/1998

Three currently available hydromechanical transmissions have been considered, all targeted at the off-highway market. For the purposes of this paper, these are designated Types “A”, “B” and “C”. Each unit has discreet qualities and types of application, and further differences will be highlighted. To provide a reference, a conventional six speed power-shift transmission has also been included, with a down-stream range change unit, held in “Hi” range; designated type “X”. The problem Ricardo have addressed in this paper is how to compare and contrast the qualities of these units for a potential user, who may not be familiar with off-high-way applications. The example considered in this study is a mobile rough-terrain crane manufacturer, contemplating a 25 tonne machine with a 193 kW engine and an on-highway max. speed of 75 kph.

Turner, Will, Anderson, Scott

Domestic Performance Torque Converter Manufacturing

J2440_199802-TEST-REC (Historical)02/01/1998

The scope of this SAE Draft Technical Report is to establish dimensional standards for high-performance domestic torque converter manufacturers. Many torque converter manufacturers build converters to their own standards. Some of these standards may be outside of the specifications that define a quality performance torque converter.

Motor Vehicle Council

Domestic Performance Torque Converter Manufacturing

J2440_199802 (Historical)

02/01/1998

The scope of this SAE Draft Technical Report is to establish dimensional standards for high-performance domestic torque converter manufacturers. Many torque converter manufacturers build converters to their own standards. Some of these standards may be outside of the specifications that define a quality performance torque converter.

Motor Vehicle Council

Transmissions-Schematic Diagrams

J647_199707 (Historical)07/01/1997

The following schematic diagrams exemplify the SAE recommended method of illustrating automotive transmission arrangements. They were developed to standardize industry practice and facilitate a clear understanding of the functional interrelations of the gearing, clutches, hydrodynamic drive unit, and other transmission components. Two variations of diagrams are used: Transmission in neutral and in gear. For illustrative purposes, some typical transmissions are shown.

Automatic Transmission and Transaxle Committee

Theoretical Investigation into the Natural Characteristic of Torsional Vibration of a Hydromechanical Vehicular Transmission System

96177008/01/1996

In this paper the working principle of hydraulic branch of the hydromechanical transmission is introduced, dynamic characteristic analysed, its actuating medium enclosed in the working space consists that of pump, soft pipeline and motor considered to be a torsional hydraulic spring whose torsional stiffness and damping provided. The multidegrees-of-freedom of the concentrated mass-elasticity discrete mechanics model is utilized to analyze the transmission system, and the finite element method is employed to model it, the torsional natural characteristic of the system are calculated, these provide the scientific basis for structural modification of controlling the vibration and noise.

Wu, Guangqiang, Liu, Qinghe, Zhao, Keding

The Flow Field Inside an Automotive Torque Converter: Laser Velocimeter Measurements

96072102/01/1996

The 3-D flow field inside an automotive torque converter was measured using laser velocimetry. For the tests, a torque converter completely machined from Plexiglas was operated at the 0.065 and 0.800 turbine/pump speed ratio, and detailed velocities were measured in 13 planes throughout the torque converter. Digital shaft encoder information was used to correlate measured velocities with the pump/turbine angular positions to generate blade-to-blade profiles, 3-D vector plots, and contour through flow plots. Results showed large flow separation regions, jet/wake flows, circulatory secondary flows, and significant flow unsteadiness in all three torque converter elements (pump, turbine, and stator). From the measured velocities, torque converter performance parameters such as mass flows, input/output torque, element incidence angles, slip factors, and vorticities were determined. Mass flows were seen to be consistent between the elements and torque results agreed well with shaft load cell

Brun, Klaus, Flack, Ronald D.

Some Conceptual Designs of Heavy Vehicle Continuously-Variable Transmissions

95213409/01/1995

Continuously-variable transmissions are reviewed with an emphasis on heavy agricultural and construction equipment. Designs of split-torque hydromechanical transmissions are discussed. The combination of powershift and hydrostatic elements should provide comfortable, stepless shifting and the ability to allow the vehicle to operate at optimum engine and travel speeds. An integration of a continuously-variable transmission and differential steering is proposed for tracked vehicles.

Schueller, John K., Khan, Naveed

Automatic Transmissions - Schematic Diagrams

J647_199506 (Historical)06/01/1995

The following schematic diagrams exemplify the SAE recommended method of illustrating automotive transmission arrangements. They were developed to standardize industry practice and facilitate a clear understanding of the functional interrelations of the gearing, clutches, hydrodynamic drive unit, and other transmission components. Two variations of diagrams are used: Transmission in neutral and in gear. For illustrative purposes, some typical transmissions are shown.

Automatic Transmission and Transaxle Committee

Dynamic Modeling and Simulation of the Ford AOD Automobile Transmission

95089902/01/1995

A transmission system model for Ford Motor Company's automatic transmission (AOD) system used in the Lincoln Town Car has been developed using the free-body diagram method (Newtonian approach). This model is sophisticated enough to represent the dynamic behavior of the transmission system, yet simple enough to use as a real time computer simulation tool, and as an embedded model within a dynamic observer. The transmission system and torque converter models presented in this paper are part of a larger powertrain system model at the Powertrain Control Research Laboratory, University of Wisconsin-Madison.

Pan, Chung-Hung, Moskwa, John J.

Development of Hydromechanical Transmission (HMT) for Bulldozers

94172209/01/1994

Conventional medium to large-sized bulldozers have a powertrain comprised of a manually operated powershift transmission connected in series with a torque converter. There is a growing need, however, for a power train that is more efficient and easy to operate, thereby increasing bulldozer productivity. One answer to this growing demand is the hydromechanical transmission (HMT) developed by Komatsu for medium to large-sized bulldozers. The HMT consists of a powershift transmission combined in parallel with a hydrostatic transmission (HST) featuring a pair of hydraulic units. The HMT has a continuously variable shifting ratio and achieves high efficiency and automatic shifting. Additionally, it has an electronic controller that controls the transmission ratio to maintain engine speed at the maximum power point. As a result, bulldozers with the HMT demonstrate greatly improved productivity over bulldozers with the conventional powertrain. Furthermore, automatic shifting releases the

Mitsuya, Hiroyuki, Otani, Keiji, Ishino, Tsutomu, Maruyama, Ryouichi, Akasaka, Toshiyuki

A Hydromechanical Transmission Optimized for Automotive Application-An Update

93300211/01/1993

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.

Folsom, Lawrence R.

Theoretical Formulation For Power Losses In Torque Converters

93170210/01/1993

In this study are equated the main power losses that occur in the torque converters. The mathematical model is developed through empirical methods, taking into consideration the fluid circulation movement similar to the forced vortex. All equations for the fluid flow sections inside the torque converter are derived.

Santini, Joaquim E., Weber, Hans L.

On Dynamic Characteristics of Passenger Car Powertrain with Hydromechanical Transmission

93291810/01/1993

In this paper, the powertrain of passenger car is supposed to be a concentrated parameter model with its inertia neglected, the transfer function of the system is deduced, the relationship of natural frequency between hydromechanical and mechanical & hydraulic system is revealed, and several measures to increase values of powertrain freqency are proposed. Finally, the computer calculated result of dynamic characteristics of the powertrain is given.

Luo, Bangjie, Wu, Guangqiang, Wu, Shurong, Luo, Lang

Mathematical Model to Predict the Performance Characteristics of the Torque Converters

92145211/01/1992

A theoretical procedure is described to predict the performance characteristics of torque converters with three elements. The mathematical model is developed assuming that the circulation motion of the fluid is similar to a forced vortex with a linear velocity distribuition from the mean radius (Rv). Therefore, all equations are developed for the flow section of the fluid inside the torque converter. The results obtained are compared with the conventional model and with the experimental measurements.

Santini, Joaquim Emanuel, Weber, Hans Ingo

The Lotus CVT and Evolution of the Smart Transmission Concept

92210609/01/1992

This paper describes the process that redirected research effort from continuously variable transmissions (CVT's) to Smart Transmissions, the electronic control of a conventional manual gearbox. Initially work was carried out on theoretical and existing CVT's, and culminated in the proposal for a system that might solve some of the practical limitations. Following further simulation work comparing the CVT against an intelligently shifted 7 speed gearbox, it was concluded that the Smart Transmission could closely match the CVT for performance and fuel consumption. This meant original targets set by using a CVT could now be met without having to develop new transmission technology. At this point research effort was changed to developing this type of electronically controlled gearbox.

Thompson, Andrew C., Lipman, John M.

Automatic and Powershift Transmissions for Trucks

91248611/01/1991

This paper reviews the development of automatic and powershift transmissions for both on-highway and off-highway trucks. Firstly, it discusses the development of the current generation of powershift transmissions and some of the technological factors that have influenced them before going on to look at some of the alternative types of automatic transmissions that have either been considered in the past or that are being considered for the future.

Mizon, R., Tuck, R. M.

A Hydromechanical Transmission Optimized for Automotive Application

91269811/01/1991

The application of hydromechanical continuously variable transmission technology to a wide variety of automotive applications is made feasible by a unique design approach. Analysis indicates that the basic design scales readily to accommodate power inputs of under 7.5 KW to over 750 KW. The first prototype has been targeted to compete in the mid-range truck and bus market segments with transmission input torques in the order of 850 N.m to 1300 N.m and a maximum torque multiplication of approximately 10:l. The problems of high cost, poor efficiency and excessive noise which prevented prior hydromechanical units from gaining acceptance for automotive applications have been eliminated or reduced to acceptable levels in the new design.

Folsom, Lawrence R.

Static Pressure Measurement in a Torque Converter Stater

91193409/01/1991

The objective of this paper is to experimentally investigate the static pressure field in a torque converter stator. Static pressure is the most reliable and useful quantity to measure since it is based on good fundamental physics and the experimental procedure is simple. Although the automotive torque converter is one of the most complicated turbomachines, static pressure measurement in this device has not been reported in the literature. Static pressure measurements were made in a stator blade passage. The measurements were taken at 72 locations under several operating conditions. Results show that: 1) the stator pressure field is three-dimensional throughout the whole range of speed ratio conditions, 2) the pressure distribution is poor at the blade tip section, 3) the well-known one-dimensional performance model can not accurately predict the radial distribution of torque from hub to tip, and 4) a two-dimensional inviscid flow model can reasonably predict the static pressure field

By, Robert R., Lakshminarayana, Budugar

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