GB/T 38074-2019Standard test method for determining the friction and wear properties of manual transmission fluid using a high-frequency—Linear-oscillation (SRV) test machine (English PDF)

1 Scope

This Standard specifies the method that uses a high-frequency linear oscillation (SRV) test machine to determine the friction and wear properties of manual transmission fluid. Its purpose is to simulate the friction behavior of automotive manual transmission synchronizer materials. This Standard is applicable to manual transmission fluid.

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

GB/T 3077, Alloy structure steels

YS/T 669, Copper alloy tube of extruded product for synchronizer rings

3 Terms and definitions, abbreviations

4 Method summary

Use a high-frequency linear SRV test machine. The notch steel ring of upper test piece and the copper plate of lower test piece adopt surface-to-surface contact. Under conditions that the test load is constant at 260N, test temperature is 60°C, the test vibration frequency is 50Hz, the test stroke is 1.00mm and the test time is 120min, conduct reciprocating vibration test and read the coefficient of friction in different test periods. After the test, observe the wear scar conditions on the copper plate surface of lower test piece. When necessary, it can use a surface topography to measure the wear volume (Wv) of its surface wear scars.

NOTE: The vibration frequency, stroke, test temperature, test load, and material of the notch steel ring of upper test piece and the copper plate of lower test piece can be changed according to the actual situation. If point or line contact is used, different shapes of test pieces can be used instead of the steel ring of upper test piece.

5 Instruments

5.1 High-frequency linear SRV test machine: See Figure 1 for the schematic diagram of test chamber structure. The load is 10N~2500N, the frequency is 1Hz~511Hz and the stroke is 0.01mm~5.0mm.

5.2 Syringe: the measuring range is 1.0mL

5.4 Surface topography (optional): 2D or 3D surface topography

8 Preparation of the instrument

8.3 Enter test procedures and step units. In the submenu of test conditions, set the following test parameters:

8.4 Enter the test measurement driver. In the submenu of test conditions type, input the following parameters:

- Names of upper, lower test pieces;

- Name of test data save file.

8.5 Conform the test conditions such as temperature, load, frequency and stroke. Enter the test steps.

9 Test steps

9.1 Use a laboratory silk or lint-free paper towel that is dipped in cleaning solvent to wipe the surface of notch steel ring of upper test piece and copper plate surface of lower test piece. Wipe repeatedly until there is no black residue on the silk. Immerse the notch steel ring of upper test piece and copper plate of lower test piece into a beaker that contains the cleaning solvent. Place in an ultrasonic cleaner to vibrate 10min. Then use a clean silk or lint-free paper towel to wipe the notch steel ring of upper test piece and copper plate of lower test piece to make sure that no streaks appear on the surface of the test piece.

9.2 Use a syringe to drop 0.4mL of specimen on the surface of the copper plate of lower test piece that has been treated according to 9.1. Make them evenly cover on the surface area of the copper plate of lower test piece.

9.3 Put the notch steel ring of upper test piece that has been treated according to 9.1 into the top ball fixture. Place in the middle of the copper plate of lower test piece with specimens. Make the specimens to form a uniform thin layer of 50N, it shall automatically apply to the test load of 260N. Run under this test load for 120min ± 15s. The test machine and software program shall stop automatically.

9.10 After the test, the test machine shall automatically stop and turn off the heating. Automatically unload. The computer shall automatically return to the initial desktop program selection interface.

9.11 Enter the data analysis program. Select the operator module. Enter the test number unit to display the graph of each parameter. Read the coefficient of friction value corresponding to each test period.

9.12 Remove the notch steel ring of upper test piece and the copper plate of lower test piece. Clean them as described in 9.1.

9.13 Read the coefficient of friction at the specified time (15min, 30min, 90min and 120min) from the graph. If it needs to conduct wear analysis or measure the wear volume (Wv), it shall conduct the surface topography measurement on the wear spots on the copper plate of lower test piece according to the manufacturer's instruction manual of 2D surface topography. Then calculate the wear volume. It shall also use a 3D surface topography to directly measure the wear volume of the copper plate.

10 Result report

10.1 Report the following test parameters:

- Temperature, °C;

- Stroke, mm;

- Frequency, Hz;

- Test load, N;

- Notch steel ring of upper test piece, number;

- Copper plate of lower test piece, number;

- Specimen name.

10.2 Report running of 15min, 30min, 90min, 120min, as well as minimum and maximum coefficient of friction values. The coefficient of friction of 120min shall prevail as the final report result. Report the coefficient of friction curve if required.

10.3 If necessary, use a surface topography to measure and report the wear volume of the copper plate of lower test piece. […]