GB/T 25962-2010 Test method for leakage of automotive wheel bearing grease under high-speed conditions

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Card type: Test method

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

• Standard number: GB/T 25962—2010
• Chinese full title: Test method for leakage of automotive wheel bearing grease under high-speed conditions
• English name: Standard test method for determining the leakage tendencies of automotive wheel bearing grease under accelerated conditions
• Replacement relationship: not provided in the available source (no replacement of any standard is mentioned)
• Adoption relationship: modified adoption by redrafting method of ASTM D4290-07 "Test method for leakage of automotive wheel bearings under high-speed conditions"
• Publication/implementation: published on 2011-01-10, implemented on 2011-05-01
• Drafting rules: drafted according to the rules given in GB/T 1.1—2009
• Main differences from ASTM D4290-07:
  • Deleted Chapter 5 and Chapter 14 of ASTM D4290-07, and the numbering of other chapters and clauses continues accordingly
  • Added to the normative references GB/T 686, GB 1922, GB/T 11121, GB/T 11122, GB/T 11117.2 and HG/T 2892 (because Chapter 7 imposes requirements on reagents)
  • The cleaning solvent was changed from pentenone to acetone
  • Deleted Chapter 5 "Significance and use" of ASTM D4290-07, and its content serves as the introduction to this standard
  • Deleted Chapter 14 "Keywords" of ASTM D4290-07 according to the drafting provisions
  • Deleted informative Appendix X1.2 of ASTM D4290-07 (the dimension conversion table in the figure), and the dimensions in the figure were converted from the imperial system to the International System of Units
• Appendix: Appendix A is an informative appendix
• Proposed by/under the jurisdiction of: proposed by the National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC 280); under the jurisdiction of SAC/TC 280/SC1
• Drafting organization: Sinopec Research Institute of Petroleum Processing
• Main drafter: Liu Zhongqi

2. Scope of application and non-applicability

• This standard specifies the determination method for the leakage of automotive wheel bearing grease under high-speed conditions.
• This standard is applicable to laboratory evaluation of the leakage of automotive wheel bearing grease under specified conditions.
• Introduction statement: This standard can be used to distinguish wheel bearing greases with significantly different high-temperature leakage characteristics; this standard is not equivalent to a long-duration life test; this standard has been proven helpful in screening automotive wheel bearing greases for leakage tendency.
• Non-applicability: no explicit "non-applicability" clause is provided in the available source.

3. Method principle

The test grease is distributed in a modified automotive front wheel hub-spindle-bearing assembly. During the test, the axial load on the bearing is 111 N, the hub speed is 1 000 r/min, the spindle temperature is maintained at 160 ℃, and operation is carried out for 20 h. After the test is completed, the leakage amount of grease and/or oil is determined, and the condition of the bearing surfaces is recorded.

4. Reagents and materials (purity / preparation)

• 7.1 Acetone: chemically pure, meeting the requirements of GB/T 686. Warning: flammable, vapors are harmful.
• 7.2 n-Heptane: chemically pure, meeting the requirements of GB/T 11117.2. Warning: flammable, harmful if inhaled.
• 7.3 Isopropanol: 99%, chemically pure, meeting the requirements of HG/T 2892. Warning: flammable.
• 7.4 Solvent naphtha: meeting the requirements for No. 3 solvent naphtha in GB 1922. Warning: flammable, vapors are harmful.
• 7.5 Machine oil: meeting the requirements of 10W in GB/T 11121 or GB/T 11122.
• 7.6 No. "00" steel wool.
• Note: further preparation instructions for each reagent are not provided in the available source.

5. Instruments and equipment

• 5.1 Test apparatus, as shown in Figure 1 and Figure 2.
  • 5.1.1 Hub-spindle-bearing assembly made according to the conventional external shape, as shown in Figure 3.
  • 5.1.2 Oven: 1800 W electric heater, controlling the spindle temperature to remain constant at 160 ℃±1.5 ℃.
  • 5.1.3 Spindle drive motor: 186 W, 1725 r/min, 120 V DC electric control, with motor torque displayed on an adjustable automatic stop instrument.
  • 5.1.4 Fan drive motor: 25 W, 1550 r/min, 120 V DC electric control.
• 5.2 Auxiliary devices: control or monitor motor speed, box temperature, spindle temperature, running time and torque.
• 5.3 A steel ring added to the original design to make leaked grease fall into the grease collector (as shown in Figure 4, respectively the grooves and steel ring of Koehler and PAM). Note: the steel ring is used to prevent leaked grease from creeping along the hub wall and then falling outside the grease collector; adding this steel ring will not affect the precision of the test results.
• 5.4 Balance: minimum weighing (original numerical value missing, requires confirmation against the source standard (source-text extraction)), sensitivity 0.1 g.
• Components labeled in Figure 1 (excerpt from source-text extraction): thermometer sleeve, temperature probe, hub, thermocouple jack, insulation material, sliding door, drive coupling, drive motor 120 W/1725 r/min, bearing thrust load device, electronic sensor, motor balance bolt, motor base, grease collector, heater 1800 W, fan, base plate.
• Components labeled in Figure 2 (excerpt from source-text extraction): fan motor 25 W/1550 r/min, fan, motor support, drive joint, motor base, thermocouple jack, drive motor, bearing thrust loading device, hub, grease collector, wax cover, base, built-in bearing LM67048 cone/LM67010 race, temperature probe, external bearing LM11949 cone/LM11910 race.
• Components labeled in Figure 3 (excerpt from source-text extraction): shock absorber (D), end cover (D), electronic sensor, rod (A), spindle (C), spring (F), rear plate (E), compression gauge (J), lock nut (G), compression nut (G), flat section, guide rod (B).

6. Recommended operating conditions

• Axial load: 111 N
• Hub speed: 1 000 r/min±50 r/min
• Spindle temperature: 160 ℃±1.5 ℃
• Running time: 20 h±0.25 h
• Motor interruption value: C = 8(T − N) + N (Formula 1), where C is the motor interruption value (A), T is the steady-state current (A), and N is the no-load motor current (A)
• Note: the motor is protected by a 30 s relay.

7. Sampling and specimen preparation

• 6 Test bearings: use LM67048-LM67010 and LM11949-LM11910 respectively as built-in and external bearings, meeting the requirements of the American Anti-Friction Bearing Manufacturers Association AFBMA standard 19—1974 (American National Standard B.3.19-1975).
• 8 Bearing preparation:
  • 8.1 Carefully take the new bearings (bearing outer ring and bearing cone) out of the packaging and place them into a 250 mL clean beaker. Clean the bearings with n-heptane to remove the rust preventive.
  • 8.2 Then clean twice more with fresh n-heptane to ensure all rust preventive is removed. A clean beaker should be used each time.
  • 8.3 Drain the n-heptane from the bearings and place the bearings on a clean silk cloth to air dry.
  • Note: an ultrasonic cleaner may be used to clean the bearings.
• 9.3 Specimen loading: weigh the built-in and external bearing cones accurately to 0.1 g; use another set of bearing outer rings and the grease loader shown in Figure 5 and Figure 6 to add the specimen into the bearing cones; use a small scraper to scrape off excess grease specimen overflowing from the bearing cones, wipe the cone shaft hole, the rear side of the bearing cone, the outer surface of the cage and the exposed roller surfaces with a clean silk cloth, and weigh again. Adjust the grease mass in the built-in and external bearing cones to 8 g±0.1 g and 2 g±0.1 g respectively (the numerical value source-text extraction here in the original text is shown as "8 ± 0.1g and 2g ± 0.1g", and the built-in bearing value requires confirmation against the source standard (source-text extraction)). Apply a thin layer of grease to the bearing outer rings.
• 9.4 Evenly apply 55 g±0.2 g grease to the inside of the hub.

8. Analytical procedure

• 9.1 Before each test, check the freedom of movement of the thrust load rod (Figure 3); if sticking is found, remove and clean the load rod and spindle hole.
• 9.2 Install the bearing outer rings into the cleaned hub according to the positions in Figure 1 and Figure 2.
• 9.3 Load the specimen (see Section 7).
• 9.4 Evenly apply 55 g±0.2 g grease to the inside of the hub.
• 9.5 Weigh the grease leakage collector accurately to 0.1 g.
• 9.6 Install the grease leakage collector, built-in cone, hub and external cone on the spindle (Figure 2). Secure the assembly on the spindle with the end cap and screws. Install the drive joint.
• 9.7 Referring to Figure 3, adjust the axial load: screw on the compression nut G until the spring F is in a position where it just presses against the rear plate E, but do not compress it. Screw the lock nut H onto the compression nut G without moving H, tighten G so that the spring F is compressed until the gauge J is inserted between H and G. Keep J in place, back off G until J is tightly clamped between H and G. Note: Insert the gauge J and adjust G to compress the spring F and apply an axial load of 111 N on the wheel bearing.
• 9.8 Insert the thermocouple into the main shaft thrust rod, and position the junction at the center of the outer bearing, then close the box cover. At this time, do not connect the motor to the drive section. Start the motor and adjust the speed to 1 000 r/min±50 r/min. Observe and record the no-load motor current value (N).
• 9.9 Turn off the motor, connect the motor to the drive section, and secure it in this position. Set the timer and start the 20 h operation. Restart the motor and readjust the speed to 1 000 r/min±50 r/min. Turn on the heater and adjust the box temperature until the shaft temperature is maintained at 160 ℃±1.5 ℃. After the shaft temperature stabilizes at the test temperature, do not adjust the box temperature again during the test.
• 9.10 The 2 h at the start of operation can form a stable operating torque and display a stable current. Record this value as the steady-state current (T). Determine the motor interruption value C according to formula (1), and set the motor to the interruption value of C.
• 9.11 Under the specified load, speed, and temperature conditions, operate the instrument for 20 h±0.25 h. If the motor current exceeds the interruption value, the test will stop automatically.
• 9.12 Open the box cover and allow the testing machine to cool naturally to about 55 ℃ for disassembly.
• 9.13 Weigh the grease loss collector to an accuracy of 0.1 g, and report the increased mass as the grease loss. The grease collector will hold 15 g before overflowing. This represents approximately 25% of the total grease fill. If the collector overflows, report the grease loss as greater than 25%.
• 10 Parts cleaning:
  • 10.1 Using a suitable scraper, remove as much grease as possible from the hub, grease collector, hub cap, and drive section.
  • 10.2 Place these parts in a suitable container (preferably stainless steel) and soak in acetone. Cover with a loose lid and gradually heat (50 ℃) until the parts are clean (takes about several hours). Avoid prolonged (overnight) heating to prevent corrosion of the parts.
  • 10.3 Remove the parts from the solvent and rinse with flowing hot water. Immediately rinse with isopropyl alcohol. Air dry. If the parts are not to be used immediately, coat with a thin layer of SAE10W machine oil.
  • 10.4 Use a suitable scraper to scrape off the grease on the shaft. Then use "00" steel wool and solvent naphtha to remove remaining deposits from the spindle. If the residue adhering to the spindle cannot be removed, remove the spindle and wash with acetone.

9. Qualitative and Quantitative Determination and Calculation Formulas

• Quantification: The mass increase of the grease loss collector after the test is taken as the grease loss, accurate to 0.1 g (9.13, 11.1).
• Overflow determination: The collector holds 15 g before overflowing, which is about 25% of the total grease fill; if overflow occurs, report the grease loss as greater than 25% (9.13).
• Calculation of motor interruption value (Formula 1):
  • C = 8(T − N) + N
  • Where: C— motor interruption value, in amperes (A); T— steady-state current, in amperes (A); N— no-load motor current, in amperes (A).
• Qualitative/phenomenon recording: Report other phenomena, such as movement of grease in the hub, condition of bearings, etc. (11.2); after the grease is removed, report any obvious adherent paint-like, gum, or varnish-like substances on the bearing surfaces (11.3). Note: Some thickeners in wheel bearing greases cannot be completely washed off the bearing with n-heptane, and a thin layer of grease thickener may remain on the bearing; this thin layer can be easily distinguished from paint, gum, or varnish-like deposits produced by lubricant degradation.

10. Precision

• 12.1 Precision: The precision of this test method is based on statistical analysis of interlaboratory cooperative test results from 2 laboratories (see Appendix A), and the reliability of test results is judged according to the following provisions (95% confidence level).
  • 12.1.1.1 Repeatability (r): For consecutive duplicate determinations of the same sample by the same operator in the same laboratory using the same instrument under the same operating conditions, the difference between the two test results should not exceed the requirement of formula (2).
    • r = 1.504 X^(1/2) (Formula 2)
    • Where: X— is the average of the two test results.
  • 12.1.1.2 Reproducibility (R): For tests of the same sample by different operators in different laboratories using different instruments under the specified test conditions, the difference between two single independent test results should not exceed the requirement of formula (3).
    • R = 3.848 X^(1/2) (Formula 3)
    • Where: X— is the average of the two test results.
• 12.2 Bias: There is no bias in determining the grease loss of automotive wheel bearing grease under high-speed conditions according to the procedure of this method, because grease loss is defined only according to this test method.
• Appendix A (Informative Appendix) Interlaboratory Cooperative Test Data: Table A.1 lists test data from 11 laboratories, with samples including G-8018, G-8019, G-8020, G-8023, G-8024, in grams. Note: The total number of laboratories is m=11+1; some laboratories have more than 1 testing machines, and this statistics considers each testing machine as 1 laboratory; X₁ is the first test, X₂ is the second test.

11. Report

• 11.1 Report the grease loss in grams weighed according to 9.13 of this standard, accurate to 0.1 g.
• 11.2 Report other phenomena, such as movement of grease in the hub, condition of bearings, etc.
• 11.3 After the grease is removed, report any obvious adherent paint-like, gum, or varnish-like substances on the bearing surfaces.

12. Normative References

• GB/T 686 Chemical reagent Acetone (GB/T 686-2008, ISO 6353-2:1983 NEQ)
• GB 1922 Solvent naphtha for paints and cleaning
• GB/T 11121 Gasoline engine oil
• GB/T 11122 Diesel engine oil
• GB/T 11117.2 Knock test reference fuels Reference fuel n-Heptane
• HG/T 2892 Chemical reagent Isopropyl alcohol (HG/T 2892-1997, neq ISO 6353-3:1987)
• American Anti-Friction Bearing Manufacturers Association Standard 19—1974 (American National Standard B.3.19-1975) (AFBMA Standard 19—1974 (ANSI B.3.19-1975))
• Note: In the original cited documents, the year numbers after GB/T 686 and the NEQ notation, and the "ncg" in HG/T 2892 are suspected to be source-text extraction noise, requires confirmation against the source standard (source-text extraction).

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.

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