NB/SH/T 0306-2013 Determination of load-carrying capacity of lubricating oils FZG Visual method

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Card type: Test method

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

• Standard number: NB/SH/T 0306—2013
• Chinese title: Determination of load-carrying capacity of lubricating oils FZG Visual method
• English title: Standard test method for evaluating the scuffing load capacity of oils (FZG visual method)
• Replacement relationship: Replaces SH/T 0306—1992 "Determination of load-carrying capacity of lubricants (CL-100 gear machine method)"; SH/T 0306—1992 was formulated with reference to IP 334/80 "Load-carrying capacity test of lubricating oils (FZG gear machine method)".
• Adoption relationship: Modified adoption of ASTM D5182-97 (2008) "Determination of load-carrying capacity of lubricating oils (FZG visual method)", redrafted according to ASTM D5182-97 (2008); structural differences are given in Appendix C.
• Previous versions: SH/T 0306—1992.
• Publication/implementation: Published on 2013-06-08, implemented on 2013-10-01; issued by the National Energy Administration.
• ICS 75.100; E 34.

2. Scope of application and non-applicability

• 1.1 specifies a test method for evaluating the load-carrying capacity (gear scuffing) of lubricating oils used for hardened steel gears. Scoring is a form of abrasive wear and is also a failure mode specified in this standard.
• It is mainly used to evaluate the load-carrying capacity of lubricating oils containing a small amount of additives (for example: industrial gear oils, transmission oils, hydraulic oils, etc.).
• It is not applicable to evaluating the load-carrying capacity of lubricating oils with high extreme pressure performance (for example: gear oils of API GL-4 and GL-5 specifications).
• 1.2 uses International System of Units [SI] units.
• 1.3 involves certain hazardous materials, operations, and equipment, but does not purport to address all safety problems associated with them; users are responsible for establishing appropriate safety and protective measures and determining the applicability of relevant regulatory limitations. For relevant safety measures and precautions, see Appendix A.
• The test method in 5.2 is used to evaluate the load-carrying capacity of oils for spur gears and helical gears (parallel shafts); the ability of the test results to evaluate gears (spur gears and helical gears) limits the scope of application of the test method, and there is no direct correlation with the test results for helical hypoid gears; it is also limited in distinguishing test oils with a small amount of additives from those without additives. Additives meeting the higher level requirements of GL-4 or GL-5 generally exceed the maximum testing capability of this test equipment, so this test method cannot be used to evaluate the load-carrying capacity of these additives (or test oils).

3. Method principle

• Summary of the method in 4: Use a FZG gear testing machine to evaluate the load-carrying capacity of lubricating oils. After the testing machine is loaded to the 1th stage, it runs at a constant speed (about 1450 r/min) (21700 revolutions), then the load is increased stage by stage until the failure stage is reached (see Table 1); from the 4th stage onward, the starting oil temperature is controlled (90 ℃). Before installing the test gears and after each stage of testing, the tooth surface condition is inspected to evaluate the cumulative scuffing condition of the tooth surfaces.
• The 6.1.2 FZG gear testing machine adopts the closed-loop power application principle, i.e., the positive force test principle, to apply the specified torque (load) to the test gears. The test gears and the drive gears are connected together through two elastic shafts. Elastic shaft 1 contains a loading clutch, and the specified torque is applied to the test system by hanging weights on the loading arm.
• Table 1 Standard FZG load stages (source-text extraction severe noise, values require confirmation):

Note: The values in the above table come from the source-text extraction text and contain obvious noise (such as "3.7/35.3/60.8/94.1/135.5/183.4/239,3/302.0/372.6/450.1/534.5", "99/407/1044/1799/2786/4007/5435/7773/8949/11029/13342/15826", etc.); they must be checked against the original text before use. The load stage combination column in the original text source-text extraction is "H+K+…", "K+W+…", etc., which cannot be reliably restored and is marked as requiring confirmation.

4. Reagents and materials (purity / preparation)

• 7.1 Cleaning solvent: Use solvent naphtha or other suitable cleaning solvent to clean the testing machine.
  • Note 1: Cleaning solvents are flammable, and their vapors are harmful. Keep away from heat sources, sparks, and open flames (see Appendix A).
  • Note 2: Solvent naphtha meets the requirements of SH 0004.
  • This standard adds "other suitable cleaning solvents" in clause 7.1 (technical difference relative to ASTM D5182-97 (2008)).
• 7.2 Test gears: Use FZG "A" type gears or domestic QCL-003 type gears; technical parameters are given in Table 2, and a schematic diagram of the gear pair profile is shown in Figure 3. Each pair of gears may be used twice, but should be cleaned thoroughly to avoid the previous test oil affecting the next test.
  • This standard adds "QCL-003 type gears" in clause 7.2.
• Table 2 Technical parameters of "A" type gears and QCL-003 type gears (source-text extraction values require confirmation):

Note: In Table 2, the correspondence between "pitch circle diameter/outside diameter" and "pinion/gear" is misaligned in source-text extraction and is marked as requiring confirmation.

5. Instruments and equipment

• 6.1 FZG gear testing apparatus
  • For a more complete and detailed description and operating instructions of the 6.1.1 test equipment, see the manual provided by the manufacturer/supplier.
  • The 6.1.2 FZG gear testing machine adopts the closed-loop power application principle, i.e., the positive force test principle, to apply the specified torque (load) to the test gears. Figures 1 and 2 give schematic diagrams of the FZG testing machine. The test gears and the drive gears are connected together through two elastic shafts. Elastic shaft 1 contains a loading clutch, and the specified torque is applied to the test system by hanging weights on the loading arm.
  • The 6.1.3 test gearbox is equipped with a heater and cooling lines to control the test oil temperature. A thermocouple is installed at one end of the test gearbox to control the heating and cooling system so as to obtain the conditions specified in the method.
  • The 6.1.4 FZG testing machine is driven by an electric motor, and at a speed of 1440 r/min the power is not less than 5.5 kW (7.4 HP). (source-text extraction original text is "1440r/mim" "5.SkW", requires confirmation)
• 6.2 Timer principle: Use a suitable timer to cut off the motor power. (source-text extraction original text "use a suitable ... cut off the motor power", specific wording requires confirmation)
• 6.3 Heating plate: Use a heating plate or suitable heating tool to heat the gears to 60 ℃~80 ℃, so as to facilitate mounting the gears on the shafts. (source-text extraction original text "607: ~801", requires confirmation)
• Figures 1 and 2 are schematic diagrams/structural diagrams of the FZG testing machine (including labels such as electric motor, pinion, gear, coupling, elastic shaft 1, drive gearbox, loading arm/loading rod, and weights).

6. Recommended operating conditions

• Test speed: constant speed approximately 1450 r/min (11.2 clause: start the motor 1450 r/min); after each stage runs for 15 min (21700 revolutions), shut off the motor.
• Starting oil temperature: for stages 1~3, follow the original text; (source-text extraction not clearly given, requires confirmation against the source standard); starting from stage 4, including all subsequent load stages, the test oil temperature at startup is controlled between 90 ℃–93 ℃ (source-text extraction original text "904–93°", requires confirmation against the source standard).
• Test oil quantity: 1.25 L.
• Loading: increase the load stage by stage according to Table 1; before the stage 1 test, first install the stage 12 load and maintain it for 2 min~3 min (without running) (see the preface and the explanation of differences in SH/T 0306—1992).
• Gear heating: 60 ℃~80 ℃ (for installation).
• Gearbox cleaning temperature: before cleaning with cleaning solvent, the gearbox temperature should drop below 60 ℃.

7. Sampling and specimen preparation

• No independent sampling chapter is provided in the available source. For test oil addition, see 10.4: add 1.25 L test oil to the test gearbox (liquid level approximately to the shaft centerline position).
• Note: To ensure thorough cleaning, approximately 1.25 L test oil may first be added to the test gearbox, the gearbox upper cover installed according to clause 10.5, no load applied, the clutch tightened, the guard cover put on, and after running without load for 3 min~5 min, drain it, and then add 1.25 L test oil. (source-text extraction noise, requires confirmation against the source standard)
• 10.1 Test gears: thoroughly clean the test gears with cleaning solvent to remove the protective layer on the gears; use a soft brush if necessary. Naturally air-dry or blow-dry the cleaned gears, and inspect (visually) the tooth surfaces for damage or corrosion. Gears with any damage or corrosion must not be used for the test.
• 10.2 Test gearbox: thoroughly clean the test gearbox and bearings with cleaning solvent to remove test oil remaining from the previous test. This cleaning step may be performed after the test is completed and the test oil drained, before disassembling the test gear assembly. It is recommended to clean the gearbox and bearings twice so as to thoroughly remove residual oil from the previous test. After draining the cleaning oil, air-dry the test gearbox and bearings.
• 10.3 Test gear assembly: use a heating plate or other suitable heating tool to heat the gears, spacers, and bearings to 60 ℃~80 ℃, and install the test gears onto the shafts at the positions indicated in Figure 4 (the large gear is installed on the left elastic shaft, and the small gear is installed on the right elastic shaft). Install the appropriate spacers, bearings, conical washers, stop washers, lock nuts, and front cover in sequence.
  • 10.3.1 Correctly installing the test gears on their respective shafts is very important for obtaining correct results.
  • Note: Incorrect installation can cause uncertain distribution of tooth surface load, resulting in unstable or lower failure stages.

8. Analysis procedure

• 11.1 Before the formal test: load to stage 2 (loads see Table 1), do not start the motor, and maintain for 2 min~3 min to ensure all clearances are in the correct positions; remove all loads before running clause 11.2.
• 11.2 Stage 1: lock the clutch with the locating pin, loosen all nuts on the clutch, and apply the stage 1 load (loads see Table 1). Tighten all nuts on the clutch (tighten the nuts in a star or cross pattern, torque magnitude 100 N·m, source-text extraction original text "magnitude 100Nm", requires confirmation against the source standard), remove all external loads, load arms, and locating pins, and put on the guard cover. Start the motor (1450 r/min), turn on the heater, and after running for 15 min (21700 revolutions), shut off the motor.
• 11.3 Stage 2: remove the locating pin and loosen all nuts on the clutch. Apply the stage 2 load according to Table 1. Tighten all nuts on the clutch (tighten the nuts in a star or cross pattern, torque magnitude 100 N·m), remove all external loads, load arms, and locating pins, and put on the guard cover. Start the motor (1450 r/min), and after running for 15 min (21700 revolutions), shut off the motor. The procedure for stage 3 is the same as above.
• 11.4 Starting from stage 4, including all subsequent load stages, the test process is similar to clause 11.2; however, starting from stage 4, the test oil temperature at startup is controlled between 90 ℃~93 ℃.
• 11.4.1 After each stage test, record and inspect the damage condition of the small gear (there is no need to remove the small gear from the shaft). According to the terminology in Chapter 3 and the examples in Figure 5~Figure 8 and the description of the worst tooth surface condition in Table 3, record the type and degree of tooth surface damage. Visually inspect the tooth surfaces without magnification; it is recommended to use a table to record the tooth surface damage condition observed at each stage.
• 11.4.2 If on 16 tooth surfaces the total adhesive wear (scuffing) or scratching width is greater than or equal to one tooth surface width (20 mm), the test fails, and that stage is the failure stage. Report the failure stage. Examples of test result evaluation are given in Appendix B.
• 11.5 Test until test failure; if failure has still not occurred after running stage 12, also terminate the test, and the test result is that stage 12 did not fail.
• 11.6 After the test is completed, the nuts on the clutch should be loosened; otherwise the test machine will be damaged.
• Note: The failure stage is based only on the small gear.
• Table 3 Tooth surface damage description and characteristics:

Note: The table lists the differences in FZG tooth surfaces; no failure forms are provided in the available source. Inspect the tooth surfaces visually at an observation distance of about 25 cm, and evaluate against the original tooth surface (source-text extraction noise, requires confirmation against the source standard).

9. Qualitative and quantitative determination and calculation formulas

• Qualitative determination: visually inspect the tooth surface damage type (polishing, scoring, scratching, scuffing) according to 11.4.1, and record according to the description in Table 3.
• Failure determination: 11.4.2 If on 16 tooth surfaces the total adhesive wear (scuffing) or scratching width is greater than or equal to one tooth surface width (20 mm), the test fails, and that stage is the failure stage.
• Result expression: report the failure stage; if the failure criterion is not reached after running stage 12, report that stage 12 did not fail.
• Calculation formulas: not provided in the available source.

10. Precision

• 13.1 Precision: judge the reliability of test results according to the following provisions (95% confidence level).
  • 13.1.1 Repeatability r: in the same laboratory, by the same operator using the same instrument, according to the same method, the difference between two consecutive test results on the same sample shall not exceed 2 load stages. r=2.
  • 13.1.2 Reproducibility R: in different laboratories, by different operators using different instruments, according to the same method, the difference between two single, independent results on the same sample shall not exceed 2 load stages. R=2.
• 13.2 Bias: because there is no generally accepted reference oil that can determine test bias, bias is not defined.

11. Report

• 12 Test report: report the test result obtained in 11.4.2. If the failure criterion is not reached after running stage 12, report that stage 12 did not fail.
• In addition to reporting the failure stage, the test report should also include the corresponding test information, such as: test oil name, gear type, test speed, test oil temperature (starting temperature), test method, pre-test gear inspection results, etc.
• This standard adds the above report content requirements in Chapter 12 (relative to the technical differences of ASTM D5182-97 (2008)).

12. Normative references

• GB/T 17754 Tribology terminology
• SH 0004 Solvent naphtha for rubber industry
• Note: For dated references, all subsequent amendment sheets (excluding errata content) or revised editions do not apply to this standard; for undated references, the latest edition applies to this standard.
• Reference standards (adoption relationship): ASTM D5182-97 (2008); IP 334/80 (historical reference).

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 Q&A reference