GB/T 38074-2019 Determination of friction and wear performance of manual transmission lubricants SRV test machine method

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Card type: Test method

1. Method number / full name / English name / replacement relationship

• Standard number: GB/T 38074—2019
• Chinese name: Determination of friction and wear performance of manual transmission lubricants SRV test machine method
• English name: Standard test method for determining the friction and wear properties of manual transmission fluid using a high-frequency—Linear-oscillation (SRV) test machine
• Replacement relationship: not provided in the available source (the foreword only states that it was drafted in accordance with GB/T 1.1—2009, and does not mention replacing any standard)
• Publication/implementation: published on 2019-10-18, implemented on 2020-05-01
• Custodian: National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC 280)

2. Scope of application and non-applicability

• Scope of application: This standard specifies a method for determining the friction and wear performance of manual transmission lubricants using a high-frequency linear vibration test machine (SRV), intended to simulate the friction behavior of automotive manual transmission synchronizer materials (the source text writes "friction behavior" as "friction action force", requires confirmation against the source standard (source-text extraction)). This standard applies to manual transmission lubricants.
• Non-applicability: no explicit non-applicability clause is provided in the available source.
• Introductory note: This standard is only a simulation test method for simulating synchronizer bench tests (such as CEC L-66-99) under 60 °C; users need to determine whether there is a correlation between its test results and actual service performance or other applications.

3. Method principle

Using a high-frequency linear SRV test machine, the upper specimen notched steel ring and the lower specimen copper disk are in surface-to-surface contact, and a reciprocating vibration test is carried out under conditions such as a constant 260 N test load, 60 °C test temperature, 50 Hz test vibration frequency, 1.00 mm test stroke, and 120 min test time, and the friction coefficient at different test time periods is read. After the test, observe the wear scar condition on the surface of the lower specimen copper disk; if necessary, a surface profilometer may be used to measure the wear volume of the surface wear scar (Wv). Note (source text): The vibration frequency, stroke, test temperature, test load, and the materials of the upper specimen notched steel ring and lower specimen copper disk may be changed according to actual conditions. If point or line contact is to be used, specimens of different shapes may be used to replace the upper specimen steel ring.

4. Reagents and materials (purity / preparation)

4.1 Reagents

• Cleaning solvent: petroleum ether, 60 °C~90 °C, analytical grade. Warning: flammable, harmful to the body.

4.2 Materials

• 6.2.1 Upper specimen notched steel ring: the material is 20CrMnTi bearing steel, meeting the requirements of GB/T 3077, HRC is 58–62, Ra 0.040 μm–0.060 μm, the parallelism and flatness of the ring surface are not greater than 0.0040 mm; the outer diameter of the upper specimen notched steel ring platform is 21 mm±0.10 mm, total thickness 6 mm±0.01 mm; wherein the ring outer diameter is 20 mm±0.05 mm, inner diameter is 17 mm±0.05 mm, ring height is 1.5 mm±0.10 mm; ring notch dimensions width × height 1 mm×1 mm. Its surface morphology must satisfy the four parameter value ranges in Table 1.
• Table 1 Surface morphology parameter ranges of the upper specimen notched steel ring (unit μm):
  • Maximum average profile height Rz: 0.200~0.350
  • Arithmetic mean deviation of profile Ra: 0.040~0.060
  • Removed peak height Rpk: 0.150~0.300
  • Removed valley depth Rvk: 0.200~0.350
• 6.2.2 Lower specimen copper disk: the material is HMn64-8-5-1.5 (TL-VW084) manganese brass, meeting the requirements of YS/T 669, HB (2.5/62.5) is 210～260, Ra 0.040 μm~0.060 μm, parallelism and flatness are both not greater than 0.0040 mm, disk diameter is 24 mm±0.10 mm, thickness 7.8 mm±0.05 mm. Its surface morphology must satisfy the four parameter value ranges in Table 2.
• Table 2 Surface morphology parameter ranges of the lower specimen copper disk (unit μm):
  • Maximum average profile height Rz: 0.450~0.650
  • Arithmetic mean deviation of profile Ra: 0.040~0.060
  • Removed peak height Rpk: 0.250~0.450
  • Removed valley depth Rvk: 0.300~0.500
• 6.2.3 Calibration oil: calibration oil provided by the instrument company, vehicle gear oil.
• 6.2.4 Calibration test specimens: standard steel ball, AISI52100 steel or similar material, HRC is 58–62, Ra 0.020 μm–0.030 μm, diameter is 10 mm±0.05 mm; standard steel disk, AISI52100 steel or similar material, HRC is 58–62, Ra 0.450 μm–0.650 μm, diameter 24 mm±0.50 mm, thickness 7.8 mm±0.10 mm.

5. Instruments and equipment

• 5.1 High-frequency linear SRV test machine: the schematic diagram of the test chamber structure is shown in Figure 1. Load force 10 N–2 500 N, frequency is 1 Hz–511 Hz, stroke is 0.01 mm~5.0 mm.
• 5.2 Syringe: range is 1.0 ml (the source text writes "range force 1.0 ml", requires confirmation against the source standard (source-text extraction)).
• 5.3 Ultrasonic cleaner.
• 5.4 Surface profilometer (optional): 2D or 3D surface profilometer.
• Figure 1 Test chamber structure description: ① base; ② piezoelectric measuring device; ③ support platform; ④ lower specimen fixture; ⑤ resistance heater and resistance thermometer; ⑥ vibration drive rod; ⑦ upper specimen fixture; ⑧ loading rod; ⑨ lower specimen copper disk; ⑩ top ball and upper specimen notched steel ring.

6. Recommended operating conditions

• Test temperature: 60 °C
• Test time: 120 min
• Test frequency: 50 Hz
• Test load: 260 N
• Test stroke: 1.00 mm
• Running-in: run in under 50 N load for 30 s, then automatically apply to the test load 260 N
• Calibration test conditions (7.2): temperature 50 °C, load 200 N (running-in load 50 N, running-in period 30 s), frequency 50 Hz, stroke 1.00 mm, time 120 min, and the test is required to start after reaching the set temperature 5 min.

7. Sampling and specimen preparation

• Sampling: no dedicated sampling clause is provided in the available source.
• Specimen amount and preparation (9.1~9.3): wipe the surfaces of the upper specimen notched steel ring and lower specimen copper disk with a laboratory silk cloth or lint-free paper towel dipped in cleaning solvent, repeatedly wiping until there is no black residue on the silk cloth; immerse the upper specimen notched steel ring and lower specimen copper disk in a beaker containing cleaning solvent, place in an ultrasonic cleaner and vibrate for 10 min, then wipe with clean silk cloth or lint-free paper towel to ensure that no streaks appear on the specimen surfaces. Use a syringe to drip 0.4 ml of sample onto the surface of the treated lower specimen copper disk, and spread it evenly over the surface area of the lower specimen copper disk. Install the treated upper specimen notched steel ring into the top ball fixture, and place it in the center of the lower specimen copper disk with the sample, so that the sample forms a uniform thin layer between the upper specimen notched steel ring and the lower specimen copper disk.

8. Analysis procedure

• 8.1 Turn on the test machine and computer, and preheat for not less than 15 min.
• 8.2 Enter the desktop software operating program, open the software connection program for online automatic detection and connection.
• 8.3 Enter the test program and step unit, and set the test parameters in the test conditions submenu (temperature 60 °C, time 120 min, frequency 50 Hz, load 260 N, stroke 1.00 mm).
• 8.4 Enter the test measurement driver program, and in the test condition type submenu input: test sample name, upper/lower specimen name, test type, test operator, test data save file name.
• 8.5 Confirm the test conditions such as temperature, load, frequency, and stroke, and enter the test steps.
• 9.4 After confirming that the test machine is not loaded, carefully place the top ball fixture with the upper specimen notched steel ring and the lower specimen copper disk containing the sample onto the test base; during installation, the lower specimen copper disk number faces outward, and the fixture fastening screw faces the number.
• 9.5 First tighten the top ball fixture with screws, then tighten the lower specimen copper disk fixture with screws; then adjust the upper specimen notched steel ring so that the steel ring notch direction faces outward and is consistent with the direction of the lower specimen copper disk fixture fastening screw, that is, perpendicular to the vibration direction (installation structure is shown in Figure 6).
• 9.6 First enter the computer operating software preloading program; the machine will automatically apply a load of 50 N for running-in test, then use a torque wrench to tighten the top ball fixture and copper disk fixture to 2.5 N·m.
• 9.7 Enter the software test run preparation program, and the machine will automatically heat up.
• 9.8 After the test temperature stabilizes at 60 °C, the testing machine will automatically start reciprocating vibration operation at the test frequency 50 Hz and test stroke 1.00 mm, and the computer displays the running curve graphs of each parameter.
• 9.9 When the machine runs in under a load of 50 N for running-in for 30 s, the test load 260 N will be automatically applied, and after running under this test load for 120 min±15 s, the testing machine and software program will automatically stop.
• 9.10 After the test ends, the testing machine automatically stops and turns off heating, automatically unloads, and the computer automatically returns 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 curve graphs of each parameter, and read the friction coefficient values corresponding to each test time period.
• 9.12 Remove the upper specimen notched steel ring and the lower specimen copper disk, and clean them thoroughly as described in 9.1.
• 9.13 Read the friction coefficient at each specified time (15 min, 30 min, 90 min and 120 min) from the curve graph; if wear analysis or wear volume (Wv) measurement is required, the surface topography of the wear scar on the lower specimen copper disk may be measured according to the 2D surface topography instrument manufacturer's instructions, and then the wear volume calculated; the wear volume of the copper disk may also be directly measured using a 3D surface topography instrument.

9. Qualitative and Quantitative and Calculation Formulas

• Friction coefficient: the ratio (3.1.3) between the friction force (F) between two objects and the normal force (N) pressing on these two objects.
• Arithmetic mean deviation of the profile Ra (Formula 1): the arithmetic mean of the absolute values of the profile departure Y within the sampling length. The original formula (1) source-text extraction is incomplete, written as "R.--≥1.1", requires confirmation against the source standard (source-text extraction). In the formula: i—— is the ordinal number of the measurement point; —— number of measurements (the original lacks a symbol, requires confirmation against the source standard (source-text extraction)). Reference GB/T 17754—2012 definition 3.16.
• Maximum mean height of the profile Rz (Formula 2): the sum of the average values of the five largest profile peak heights Y and the five largest profile valley depths Y within the sampling length. The original formula (2) source-text extraction is incomplete, requires confirmation against the source standard (source-text extraction). In the formula: i—— is the ordinal number of the measurement point. Reference GB/T 17754—2012 definition 3.15.
• Wear volume Wv: the amount of volume loss of the copper plate surface material after the test (3.1.9).
• Seizure determination (3.1.10 Note): a sharp increase in friction coefficient, increased wear, or the appearance of abnormal noise and vibration often indicates that seizure has occurred; in this standard, the increase in friction coefficient is shown by the curve drawn by the recorder rising from a stable form to a fixed height.
• The final reported result is based on the friction coefficient of 120 min.

10. Precision

• 11.1.1 General: The precision of this standard is based on cyclic tests conducted on SRV testing machines in 9 laboratories using 9 lubricating oil samples, with 9 samples respectively run in 9 laboratories at 120 min, the average friction coefficient range being 0.047~0.153, and obtained after statistical analysis and calculation of test data with reference to GB/T 6683. The precision statistical test conditions are: test temperature 60 °C, test load 260 N, test frequency 50 Hz, test stroke 1.00 mm and test running time 120 min. Judge the reliability of test results according to the following provisions (95% confidence level).
• 11.1.2 Repeatability r: For measurements made by the same operator in the same laboratory using the same instrument on the same sample, the difference between two consecutive test results (friction coefficient at 120 min) shall not exceed the value specified in Formula (3):
  • r = 0.002 92X − 0.978 (Formula 3)
  • In the formula: X—— is the average of the two measurement results of the sample.
• 11.1.3 Reproducibility R: For measurements made by different operators in different laboratories using different instruments on the same sample, the difference between two single, independent test results (friction coefficient at 120 min) shall not exceed the value specified in Formula (4):
  • R = 0.001 77X − 1.482 (Formula 4)
  • In the formula: X—— is the average of the two measurement results of the sample.
• 11.2 Bias: There is no bias in evaluating the friction characteristics of lubricating oils using this test method, because the friction coefficient is defined only according to this test method.

11. Report

• 10.1 Report the following test parameters: temperature (°C); stroke (mm); frequency (Hz); test load (N); upper specimen notched steel ring number; lower specimen copper disk number; sample name.
• 10.2 Report the running 15 min, 30 min, 90 min, 120 min, as well as the minimum and maximum friction coefficient values; the final reported result is based on the friction coefficient of 120 min. If necessary, the friction coefficient curve may be reported.
• 10.3 If necessary, a surface topography instrument may be used to measure and report the wear volume of the lower specimen copper disk.

12. Referenced Documents

Normative referenced documents (Chapter 2):

• GB/T 3077 Alloy structural steel
• YS/T 669 Extruded copper alloy tube for synchronizer gear rings

References:

• [1] GB/T 6683 Method for determining precision data of petroleum product test methods
• [2] GB/T 17754—2012 Tribology terminology
• [3] GB/T 18778.2—2003 Geometrical product specifications (GPS) Surface texture: Profile method — Surfaces having stratified functional properties — Part 2: Height characterization using the linear material ratio curve
• [4] CEC L-66-99 Evaluation of the Synchromesh Endurance Life using the FZG SSP 180 synchromesh test rig.

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick Reference Q&A