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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 is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluid combinations. The specific purpose of this document is to define a µPVT test for the evaluation of the variation of wet friction system low speed slip characteristics as a function of speed, temperature, and pressure. This procedure is intended as a suggested method for both suppliers and end users. The only variables selected by the supplier or user of the friction system are: Friction material Fluid Reaction plates Oil flow (optional) These four variables must be clearly identified when reporting the results of this test.

The following is a list of the most common terminology used in describing automatic transmission functions.

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 NOTE: For more information about these characteristics and the design of hydrodynamic drives, refer to “Design Practices: Passenger Car Automatic Transmissions,” SAE Advances in Engineering, AE-18 (Third Ed.) or AE-29 (Fourth Ed.).

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.

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 specific purpose of this SAE Recommended Practice is to define a procedure to determine intrinsic properties of friction materials such as compressive modulus and rebound/recovery time at specific fatigue test pressures. Results from this test will both independently characterize the friction material and serve as input to the compression fatigue test. NOTE: If this test is intended to determine the rebound interval for the compression fatigue test, then the maximum test pressure (Pmax) in this procedure must be selected with future fatigue testing levels in mind. It is important that the rebound time is sufficient at the maximum apply pressure to allow the matieral to rebound back to its original thickness. Standard reporting processes are recommended.

This test procedure is intended to apply to hydraulic pump suction filters and strainers used in automotive automatic transmissions that include hydraulic power pumps. The various paragraphs of Section 5 include a variety of tests and alternative tests that are not applicable to all filters and applications, so the engineer must specify which tests are to be performed for a particular application. These test procedures are intended to evaluate filter functional performance characteristics only, durability is not evaluated under this standard. Filter design requirements must be specified by the engineer on the filter assembly drawing, an applicable engineering specification, or summarized on an application data sheet similar to that found in this recommended practice. See Figure 6. Pressure circuit filters, both barrier and system contamination control types, are not covered under this standard.

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.

The definitions and illustrations in this SAE Recommended Practice are intended to establish common nomenclature and terminology for automotive transmission one-way clutches.

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 NOTE: For more information about these characteristics and the design of hydrodynamic drives, refer to “Design Practices: Passenger Car Automatic Transmissions,” SAE Advances in Engineering, AE-18 (Third Ed.) or AE-29 (Fourth Ed.).

Figures 1 through 5 illustrate in simplified form some of the more common planetary gear arrangements in order to establish applicable terminology. Figures 6 and 7 provide additional examples that use elements of those gear arrangements. Gear ratio is the numerical ratio of input to output speed.

The following is a list of the most common terminology used in describing automatic transmission functions.

The scope and purpose of this SAE Recommended Practice is to provide a standard pattern or sequence for the manual control of automatic transmissions in passenger cars and light-duty trucks. This generally refers to left hand drive mechanical shift applications.

To provide a Recommended Practice for validating the function and integrity of an automatic transmission park mechanism with its associated control system and environment.

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)

The definitions and illustrations in this SAE Recommended Practice are intended to establish common nomenclature and terminology for automotive transmission one-way clutches.

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 NOTE: For more information about these characteristics and the design of hydrodynamic drives, see “Design Practices—Passenger Car Automatic Transmissions,” SAE Advances in Engineering, AE18 or AE29

The following is a list of the most common terminology used in describing automatic transmission functions.

The scope and purpose of this SAE Recommended Practice is to provide a standard pattern or sequence for the manual control of automatic transmissions in passenger cars and light-duty trucks. This generally refers to left hand drive mechanical shift applications.

To provide a Recommended Practice for validating the function and integrity of an automatic transmission park mechanism with its associated control system and environment.

To provide a means of obtaining the efficiency characteristics of automatic transmissions and automatic transaxles. It outlines dynamometer tests that map the steady-state characteristics over a range of operations of an automatic transmission/automatic transaxle and provides a method of presenting test data. This procedure must be followed, with similar test facilities so that results obtained from different laboratories are comparable. For this SAE Recommended Practice, the transmission is defined as the complete automatic transmission or transaxle assembly between the engine and the driveshaft(s) used to effect a ratio change in transmitting power. For 4WD/AWD, it does not include transfer case or power take off subsystems. This test procedure deals with the aspect of conducting complete transmission and transaxle assembly testing.