SH/T 0338-1992 Determination of Low-Temperature Torque of Ball Bearing Greases

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

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

• Standard number: SH/T 0338-92 (confirmed in 2004)
• Full name: Determination of Low-Temperature Torque of Ball Bearing Greases
• English name: not provided in the available source
• Replacement relationship: replaces SY 2730-84
• Reference adoption: American Society for Testing and Materials standard ASTM D1478-1980 "Determination of Low-Temperature Torque of Ball Bearing Greases"
• Approval/implementation: approved by China Petrochemical Corporation 1992-05-20, implemented on 1992-05-20

2. Scope of application and non-applicability

• This standard specifies the determination method for low-temperature torque of ball bearing greases.
• Applicable to the determination of the low-temperature torque characteristics of greases on a ball bearing grease low-temperature torque testing machine at temperatures below -20°C.
• Not applicable: not provided in the available source.

3. Method principle

A qualified, clean D204 type bearing is repeatedly filled with the sample using a grease cup, held stationary at the specified temperature for 2h, then rotated at a speed of 1r/min±0.05r/min on the bearing inner ring, and the grease resistance acting on the bearing outer ring is measured. Since this resistance is proportional to torque, it is expressed as the measured starting torque and running torque.

• Starting torque — the maximum torque measured at the start of rotation.
• Running torque — the average value of torque after rotating for the specified time (60min).

4. Reagents and materials (purity / preparation)

• 3.1 Test bearing: select D204 type single-row radial ball bearing (composed of eight steel balls with a diameter of 7.9mm and a steel cage). Its radial clearance should be 0.008~0.018mm.
• 3.2 Oil for checking bearings: lubricating oil with a kinematic viscosity of 100° at 28.7~32mm²/s.
• 3.3 Rubber industry solvent naphtha.
• 3.4 Petroleum ether: 60~90°C, analytical reagent.
• 3.5 Silicone oil.
• Desiccant (such as activated alumina, etc.): see 6.7.

5. Instruments and equipment

• 4.1 Test apparatus (as shown in Figure 1), consisting of the following parts:
  • Low-temperature chamber: any well-insulated chamber with an internal volume of 0.03m³ or larger may be used. The air temperature inside the chamber can be controlled and maintained within the range of 0~-70°C±0.5°C. A baffle is provided at the cooling medium outlet inside the chamber to prevent direct contact between the test bearing and the cooling medium.
  • Transmission device: the transmission mechanism is shown in Figure 2. The test bearing is mounted on the test shaft. The height of the shaft shoulder should not be higher than the shoulder of the bearing inner ring. A flat washer with a thickness of not less than 1.6mm and a locking screw are used to press the bearing inner ring tightly onto the 1r/min test shaft.
  • Torque test device: a balanced squirrel-cage load bearing housing. The total mass of the bearing housing is adjusted to 454g±3g. As shown in Figure 3.
  • Torque measuring device: a calibrated dynamometer with a surface diameter of 178mm and a range of 0~1.8kg or larger. Accuracy per division 7g.
• 4.2 Special grease loader: composed of a grease cup, a mandrel and a pressing plate. The mandrel and grease cup are shown in Figure 4 and Figure 5 respectively.
• Figure 1 Test apparatus composition: 1— dynamometer; 2— force measuring cord; 3— temperature control thermocouple; 4— low-temperature chamber; 5— gear reducer; 6— motor (186W); 7— squirrel-cage load bearing housing; 8— dry ice outlet baffle plate; 9— dry ice regulating valve.
• Figure 2 Transmission mechanism: 1— low-temperature chamber; 2— test bearing housing; 3— load disc; 4—1r/min test shaft; 5— non-metallic insulating sleeve; 6—186W motor, 1725r/min (full load); 7— gear reducer, speed ratio 1740/1.
• Figure 3 Bearing housing component materials: bearing housing material 40 steel; fastening cover material 40 steel; load disc material 40 steel; load ring material brass; screw material stainless steel; total mass 454g±3g.
• Figure 4 Mandrel; Figure 5 Grease cup (grease cup base plate, grease cup ring, material: brass or aluminum).

6. Recommended operating conditions

• Test temperature: below -20°C (scope of application); the air temperature inside the low-temperature chamber can be controlled and maintained at 0~-70°C±0.5°C.
• Constant temperature time: 2h (stationary constant temperature).
• Test temperature difference: maintained within ±0.5°C.
• Rotation speed: bearing inner ring 1r/min±0.05r/min.
• Running torque measurement time: after rotating for the specified time 60min.
• Bearing housing torque radius: 0.065m.
• Dry ice regulating valve opening: when the test temperature is required to be above -50°C, during the constant temperature period the regulating valve at the dry ice inlet is adjusted to an opening of about 1/3, and the baffle plate should be aligned with the edge of the dry ice inlet gland; when the test temperature is required to be below -50°C, the valve opening should be increased accordingly, and the baffle plate should be moved away completely.

7. Sampling and sample preparation

• 6.1 The test bearing should be cleaned twice with solvent naphtha, then rinsed twice with petroleum ether. Place the cleaned bearing in an oven and dry it at 100°C for 20min, or blow it dry with a hot air blower. Before loading the sample, the bearing must be cooled to room temperature, and the bearing should be turned by hand to check whether it is normal.
• 6.2 Mount the clean, dry bearing on the mandrel (see Figure 4), secure the inner ring of the bearing with a shim and screw, and use a clean steel scraper to load the sample into the grease cup of the special grease loader (see Figure 5), filling 3/4 of the grease cup, avoiding the inclusion of air bubbles as much as possible. Then press the bearing into the sample in the cup, and slowly rotate the inner ring back and forth in both directions so that the sample can enter all parts of the bearing. When the end face of the bearing is aligned with the upper end face of the grease cup, pull out and remove the bearing. Then reverse the bearing end face and refasten it, press the bearing directly into the grease cup again, and when the end face of the bearing is aligned with the upper end face of the grease cup, slowly pull out the bearing; scrape off excess sample adhering to the edge of the bearing, remove visible air bubbles and fill with sample, then remove the mandrel and level both ends of the bearing with a scraper. The test bearing loaded with sample must not be rotated before measuring the starting torque, so as to facilitate the repeatability of test results.
• Note: During the entire operation of loading the sample into the bearing, it should be carried out in a clean and dry environment.

8. Analysis steps

• 5.1 Calibration of the test apparatus: regularly calibrate the temperature control instrument of the test apparatus and provide the calibration value to ensure the accuracy of test data. Regularly calibrate the dynamometer of the test apparatus using ordinary balance weights.
• 5.2 Selection of test bearing: clean and dry the D204 type test bearing whose radial clearance has been checked to meet the requirements with solvent naphtha, then gently turn it by hand; inflexibility is not allowed. Use lubricating oil with a kinematic viscosity of 100°C at 28.7~32mm²/s to check the running torque of the bearing. The checking steps are as follows: at room temperature, apply 1 drops of oil in each of the 120° directions to the bearing under test, for a total of 3 drops. After turning it back and forth by hand, install the bearing into the bearing housing of the test apparatus. Measure the running torque with the dynamometer. The bearing under test is run for a total of 3min; first pre-run for 2min, and complete the measurement during the 3min running period. Its average torque value shall not exceed 2.0mN·m, and its maximum torque value shall not exceed 2.5mN·m.
• 6.3 Carefully install the bearing loaded with sample into the bearing housing.
• 6.4 When the temperature inside the low-temperature chamber has been pre-cooled to the temperature required for the test, open the door of the low-temperature chamber, install the test bearing and bearing housing onto the test shaft and secure them. During installation, be careful not to rotate the test bearing.
• 6.5 Check the torque measuring cord and apply a little silicone oil to ensure it does not freeze or touch the hole wall, and ensure that the torque measuring cord is in a taut state. During cooling, seal the through hole tightly with a two-piece rubber stopper. The rubber stopper should be removed before starting.
• 6.6 Hang the force measuring cord on the hook of the outer ring of the bearing housing, and adjust the cord until it is nearly taut. At this time, the hook on the outer ring must exceed the tangent point, and at least deflect downward to the position of 90°, so as to ensure that the force measuring cord will not slip off the edge of the outer ring of the bearing housing. Bearing housing torque radius 0.065m.
• 6.7 Close the door of the low-temperature chamber, continue cooling to the temperature required for the test, then start timing, maintain constant temperature for 2h, and the temperature difference of the test temperature should be maintained within ±0.5°. During the constant temperature period, do not rotate the test bearing, otherwise the test is invalid. In order to prevent excessive condensation of moisture in the air, place some desiccant (such as activated alumina, etc.) in the low-temperature chamber before the test.
• 6.8 To ensure the smooth progress of the test, when the test temperature is required to be above -50°C, during the constant temperature period, the opening of the regulating valve at the dry ice inlet should be adjusted to about 1/3, and the baffle plate should be aligned with the edge of the dry ice inlet gland; when the test temperature is required to be below -50°C, the opening of the regulating valve at the dry ice inlet should be increased accordingly, and the baffle plate should be moved away completely.
• 7.1 Starting torque: start the drive motor, observe the dynamometer pointer, and record the maximum reading reached. This reading appears within a few seconds after starting operation. Multiply the scale reading value (lb) by the value K as the starting torque value, mN·m.
• 7.2 Running torque: continue rotating the test shaft for 60min, keep the temperature difference of the test temperature within ±0.5°C, observe the average reading of the dynamometer within 15s after 60min, multiply this reading value (lb) by the value K, and record this value as the running torque value, mN·m.
• 9 Repeat test: if a repeat test is to be carried out, the bearing should be cleaned and reloaded with new sample, and the above operation steps should be followed again.

9. Qualitative and quantitative determination and calculation formula

• The torque value of the sample M (mN·m) is calculated according to the following formula: M = K·P Where: K—— constant (289); P—— dynamometer reading, lb.
• Note: The constant 289 of the value K is obtained by converting the dynamometer scale reading value (lb) to mN and then multiplying by the bearing housing torque radius 0.065m.
• 11 Report results: each test in this standard can obtain the following two values: starting torque value and running torque value. The arithmetic mean of the two repeated determination results of the two values is taken respectively as the starting torque value and running torque value of the sample.

10. Precision

Use the following values to judge the reliability of the results (95% confidence level).

• 10.1 Repeatability: the difference between two results obtained by the same operator in repeated determinations shall not exceed the following values.
  • Starting torque, mN·m: 34 (percentage of the average value)
  • Running torque, mN·m: 78 (percentage of the mean)
• 10.2 Reproducibility: the difference between the results provided by two laboratories shall not exceed the following values.
  • Starting torque, mN·m: 79 (percentage of the mean)
  • Running torque, mN·m: 132 (percentage of the mean)
• Requires confirmation (source-text extraction): the correspondence between the values in 10.1 and 10.2 and the items was extracted according to the original layout; the original table structure is misaligned in source-text extraction; the correspondence between the values 34, 78, 79, 132 and "starting torque/running torque" requires confirmation (source-text extraction).

11. Report

• Each test of this standard can obtain the following two values: the starting torque value and the running torque value. The arithmetic mean of the two replicate determination results for each of the two values is taken as the starting torque value and the running torque value of the test sample, respectively.
• Other report format requirements: not provided in the available source.

12. Normative references

• ASTM D1478-1980 "Determination of low-temperature torque of ball bearing greases" (adopted by reference).
• Other normative references: not provided in the available source.

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