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Standard

SAE No. 2 Friction Test Machine 6000 rpm Stepped Power Test

2019-07-24
CURRENT
J2488_201907
This SAE Recommended Practice is intended as the definition of a standard test, but may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use. The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems. The specific purpose of this document is to define a 6000 rpm stepped power test for the evaluation of wet friction system performance variation as a function of power level. This procedure uses an initial engagement speed of 6000 rpm and is intended as a standard procedure for common use by both suppliers and end users.
Standard

SAE No. 2 Friction Test Machine μPVT Test

2019-05-31
CURRENT
J2490_201905
This SAE Recommended Practice is intended as the definition of a standard test, which may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use. The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems. The specific purpose of this document is to define a μPVT Test for the evaluation of the variation of wet friction system performance as a function of speed, temperature, and pressure. This procedure is intended as a standard for both suppliers and end users. The only variables selected by the supplier or user of the friction system are: a Friction material b Fluid c Reaction plates These three variables must be clearly identified when reporting the results of this test.
Standard

SAE No. 2 Friction Test Machine 3600 rpm Stepped Power Test

2019-05-23
CURRENT
J2487_201905
This SAE Recommended Practice is intended as the definition of a standard test, but may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use. The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems. The specific purpose of this document is to define a 3600 rpm Stepped Power Test for the evaluation of wet friction system performance variation as a function of power level. This procedure uses an initial engagement speed of 3600 rpm and is intended as a standard procedure for common use by both suppliers and end users.
Technical Paper

Implementation of Torque Hole Filling for Transmission Shift Control

2018-04-03
2018-01-1169
Torque Hole Filling (THF) is a model based approach for controlling the automatic transmission clutches and input torque during a part-pedal upshift or zero-pedal downshift. A desired transmission output torque is first calculated and then the clutches and input torque are controlled to achieve that output torque. This is a system design approach with drivability as one of the direct design objectives. This paper presents the control design and implementation of Torque Hole Filling. First, the paper introduces the topic, defines the terms, and explains the basic operation and intended result. Next, it describes how it works with one instance of implementation and its corresponding dynamics equations, for both torque transfer and ratio change phases. Lastly but most importantly, it covers the various robustness considerations for real-world applications.
Journal Article

Statistical Modeling of Plate Clearance Distribution for Wet Clutch Drag Analysis

2017-10-08
Abstract Wet clutch packs are the key component for gear shifting in the step-ratio automatic transmission system. The clutch plates are coupled or de-coupled to alter gear ratios based on the driver’s actions and vehicle operating conditions. The frictional interfaces between clutch plates are lubricated with automatic transmission fluid (ATF) for both thermal and friction management. In a 10-speed transmission, there may be as many as 6 clutch packs. Under typical driving conditions, 2 to 3 clutch packs are open, shearing ATF and contributing to energy loss. There is an opportunity to improve fuel economy by reducing the associated viscous drag. An important factor that directly affects clutch drag is the clearance between rotating plates. The axial position of clutch plates changes continuously during operation. It is known in practice that not only the total clearance, but also its distribution between the plates affects the viscous drag.
Standard

SAE No. 2 Friction Test Machine µPVT Test

2012-08-06
HISTORICAL
J2490_201208
This SAE Recommended Practice is intended as the definition of a standard test, which may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use. The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems. The specific purpose of this document is to define a µPVT Test for the evaluation of the variation of wet friction system performance as a function of speed, temperature, and pressure. This procedure is intended as a standard for both suppliers and end users. The only variables selected by the supplier or user of the friction system are: a Friction Material b Fluid c Reaction Plates These three variables must be clearly identified when reporting the results of this test.
Standard

Glossary of Terms - Lubricated Friction Systems

2012-03-19
CURRENT
J1646_201203
This SAE Recommended Practice defines the principal terms and equations pertaining to automotive automatic transmission clutch plate, band, or other wet-friction systems. The terms apply directly to friction-system testing as is typically conducted on inertia-stop test equipment. Some terms can be directly applied to the analysis of friction in the transmission or brake assembly and other friction-test equipment. The glossary presents terms used to describe the set-up, testing, and results of tests as shown in Figure 1, which were taken on a clutch SAE No. 2 machine. The glossary is intended to provide a collection of definitions in the hope of eliminating confusion in development and their application to passenger cars and trucks. This document focuses on the terminology of friction-system testing. References for this type of testing are shown in Section 2.
Journal Article

Spin Loss Computation for Open Clutch Using CFD

2011-04-12
2011-01-1238
Open clutch spin loss computation is of interest for new clutch designs. It is desirable to minimize open clutch spin loss. Spin loss in automatic transmission clutches is mainly due to the viscous shear of the transmission fluid. Depending on the relative rotational speed of the plates the spin loss varies. At low rotational speeds the gap between the plates is filled with ATF (Automatic Transmission Fluid) and spin loss increases linearly with the rotational speed. At higher speeds the ATF layer, which is held together primarily by surface tension, begins to breakdown due to higher centrifugal forces and air pockets form at outward radial locations of the clutch plates. This results in a decrease in spin loss for the open clutch. CFD (computational fluid dynamics) modeling is an attractive option in calculating the spin loss for an open clutch.
Standard

SAE No.2 Friction Test Machine 6000 r/min Stepped Power Test

2006-08-16
HISTORICAL
J2488_200608
This SAE Recommended Practice is intended as the definition of a standard test, but may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use. The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems. The specific purpose of this document is to define a 6000 r/min Stepped Power Test for the evaluation of wet friction system performance variation as a function of power level. This procedure uses an initial engagement speed of 6000 r/min and is intended as a standard procedure for common use by both suppliers and end users. The only variables selected by the supplier or user of the friction system are:a. Friction Material b. Fluid c. Reaction Plates.
Standard

Fluid for Passenger Car Type Automatic Transmissions

2000-02-22
CURRENT
J311_200002
This SAE Information Report details some of the equipment and procedures used to measure critical characteristics of automatic transmission fluid (ATF) used in current automatic transmissions. It is intended to assist those concerned with the design of transmission components, and with the selection and marketing of automatic transmission fluids for the use in passenger car and light-duty truck automatic transmissions. The information contained herein will be helpful in understanding the terms related to properties, designations, and service applications of automatic transmission fluids.
Technical Paper

Fundamental Studies on ATF Friction I.

1997-05-01
971621
Automatic transmission clutches are complex tribological systems. Frictional performance is controlled by the interaction of base fluids, additive components, composition clutches, and steel reaction plates with varying energy inputs and thermal stresses in an oxidizing environment. This paper, rather than addressing fully formulated fluid performance in such a system, takes a more fundamental approach where the number of system variables is reduced and the relative effects of formulation variables on system performance can be better examined. Relationships among observed friction performance, system oxidation, friction member condition, and representative performance additives are explored using a synthetic base fluid and a conventionally refined mineral base fluid.
Technical Paper

The Effects of Water on Cellulose-Based Frictional Surfaces in Automatic Transmission Clutch Plates

1996-10-01
961917
A bench scale apparatus and accelerated test protocol were developed to evaluate the effect of contamination of automatic transmsission fluid by mg/kg levels of water on cellulose frictional clutch surfaces. The testing indicated that water added at levels as low as 600 mg/kg migrated to the surface of untreated paper frictionals and contributed to loss of the paper coating and erratic torque transfer properties. Treated, “high performance” paper frictional surfaces showed less physical damage but the same torque transfer effects from water contaminated ATF. A mechanism of the water coating, swelling and weakening the hydrophillic cellulose fibers, with subsequent destruction due to hydrodynamic shear was proposed.
Standard

SAE No. 2 Clutch Friction Test Machine Guidelines

1996-09-01
HISTORICAL
J286_199609
This SAE Recommended Practice is intended as a guide toward implementation of a standard practice but may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use. The SAE No. 2 friction test machine is used to evaluate the friction characteristics of automatic transmission plate clutch with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems.
Technical Paper

The Effect of Separator Flatness on the Performance and Durability of Wet Friction Clutches

1993-03-01
930915
The automatic transmission clutch represents a complex system involving critical interactions between the separator plates, fluid, operating conditions and friction material. This paper focuses on the effect of separator plate flatness on the performance and durability of two friction materials on an SAE #2 machine. The data from this study shows that flat separator plates yield higher dynamic coefficients and lower wear when compared to non-flat plates. These effects were obtained for separator plates with peak-to-peak departure from flatness values between approximately .08mm and .25mm. In addition, other variables such as material elastic modulus, separator plate thickness, and material operating pressure were studied. The use of soft friction materials to improve performance with non-flat reaction plates was quantified.
Technical Paper

Control of Band/Drum Interface Temperature in Automatic Transmissions and the Impact Upon Friction System Durability

1990-10-01
902147
The importance of controlling band/drum interface temperature to maintain friction system durability in an automatic transmission clutch is investigated in this paper. Frictional durability is extremely important to assure smooth, consistent shifts and long transmission life. A statistically designed series of experiments was run in a SAE No. 2 band test machine to determine the parameters which impact interface temperature. Sump level, sump temperature, engagement speed, system inertia, direct lubrication of the drum surface, and engagement time were all examined. The analysis reveals each of these parameters, with the exception of engagement time, directly influences interface temperature under the tested conditions. Interface temperature was then linked to frictional system stability. This was accomplished through a second series of experiments where interface temperature was varied by changing only one of the previously identified parameters.
Technical Paper

Optimizing Automatic Transmission Clutch Lining Load Distribution Using Finite Element Analysis

1990-02-01
900559
A Finite Element Analysis technique was used to predict the clutch lining load distribution in automatic transmissions. This technique is explained and demonstrated on several clutch designs. The analysis shows the importance of rigid backing plates and optimum piston apply points. The benefit of tapered apply plates is also discussed. The importance of having a uniform clutch lining load distribution is described as it relates to clutch torque and energy capacity. THE PURPOSE of this paper is to discuss the importance of clutch lining load distribution for automatic transmissions as it relates to torque and clutch energy capacity. The design variables that affect these will be presented. Clutch pack compliance versus rigidity will also be addressed. A finite element technique for calculating the clutch lining load distribution will be discussed. This technique will be demonstrated on several clutch designs.
Technical Paper

An Analysis of Automatic Transmission Clutch-Plate Temperatures

1972-02-01
720287
Automatic transmission clutch failures and rapid oxidation of the transmission fluid have sometimes been attributed to high temperatures in the clutch pack. For the purpose of estimating these temperatures, an analysis was made of the clutch system, and a solution was developed from the partial differential equations of heat conduction with appropriate boundary conditions. The solution thus obtained was verified experimentally. There were several important conclusions to this study. The maximum temperature rise occurs somewhat earlier than the end of the lockup time. The interface temperature rise increases as the lockup time decreases for a fixed amount of energy input. The ratio of heat flux entering the reaction plate to that entering the composite plate is not constant, as has been assumed by others. The heat absorbed by the fluid outside the clutch pack is negligible during the short lockup time. Temperature rises for some typical cases are computed.
Standard

SAE No. 2 Clutch Friction Test Machine Guidelines

1972-01-01
HISTORICAL
J286_197201
This SAE Recommended Practice is intended as a guide toward implementation of a standard practice but may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use. The SAE No. 2 friction test machine is used to evaluate the friction characteristics of automatic transmission plate clutch with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems. This Standard is intended for common use by both suppliers and end users to define minimum test machine requirements to allow objective comparisons of wet friction material system performance.
Technical Paper

Putting Automatic Transmission Clutch Friction Researchers on Speaking Terms

1967-02-01
670051
With the object of improving the technique of testing and specifying friction materials, a new type of friction material test fixture has been developed by the SAE Friction Subcommittee. This is a completely self-contained machine especially designed for cyclic testing and quality control work. This does not replace, but rather supplements, the steady state type friction test fixture (SAE No. 1) previously developed by the committee. This fixture, known as the SAE No. 2 test fixture, is designed to test clutch packs in an environment which is as close as possible to that of the friction elements in an automatic transmission. Both friction material manufacturers and users are employing this machine for quality control, component selection, and evaluation of friction materials and lubricants.
Technical Paper

A NEW BENCH TEST FOR EVALUATING CLUTCH PLATE LUBRICATION

1963-01-01
630029
A new, low cost, simple and compact bench type machine has been developed for investigating automatic transmission clutch plate lubrication. The energy absorbed per unit of clutch facing area during clutch engagement is comparable to that absorbed by the clutch during a full-throttle upshift in a car. The machine uses full-size clutch plates and requires a 13-ounce sample of fluid. Condition of the clutch plates after running under cycling conditions correlates with that found in an engine-transmission-dynamometer cycling test.
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