ASTM D3336 Test Method for Life of Lubricating Greases in Ball Bearings at Elevated Temperatures
5. Apparatus
5.1 Test Spindle (see Fig. 1, Fig. 2, Fig. 3 and Fig. 4), capable of operating at speeds of 10 000 rpm and temperatures as high as 371°C (700°F). The test bearing seat dimension shall be 19.99 to 20.00 mm (0.7870 to 0.7874 in.). For spindles having the test bearing and the support bearing in the same housing (CRC Type, Figs. 1, 2 and 3) (Note 2) the internal construction of the spindle shall be such that the outboard support bearing, or both bearings are free to float axially in the housing. In designs where both bearings are free to float, the spindle shaft shall have a 0.508 to 0.762 mm (0.020 to 0.030 in.) free axial movement or end play. The outboard bearing seat dimension should be 19.99 to 20.00 mm (0.7870 to 0.7874 in.).
5.1.1 The test unit design (Fig. 1 and Fig. 2) should be such that a finger spring washer produces a 22 to 67 N (5 to 15 lbf) thrust load on the floating outboard support bearing.

5.2 Bearing Housing:
5.2.1 For CRC Type Spindles - The bearing housing diameter shall be 47.005 to 47.021 mm (1.8506 to 1.8512 in.) to give proper bearing mounting. Construction shall be such that the test bearing is equipped with flush spacers or shields to confine the grease to the bearing. The spacers or shields shall have a clearance between the inside diameter and the shaft of 0.127 to 0.178 mm (0.005 to 0.007 in.) per side.

NOTE 1 - This type of spindle is described in CRC Research Technique for the Determination of Performance Characteristics of Lubricating Grease in Antifriction Bearings at Elevated Temperature (CRC Designations L-35-54 and CRC L-35-62).

5.2.2 For Navy Type Spindles (Test Bearing Mounted Outside Spindle Housing) - The bearing housing shall be constructed of material similar to that of the test bearing and shall be tempered to retain dimensional stability at temperatures up to 371°C (700°F). Internal diameter shall be 47.005 to 47.021 mm (1.8506 to 1.8512 in.). The housing cover shall be flush fitting to confine the grease to the bearing. Provision shall be made for insertion in the housing of one or two small thermocouples which shall lightly press on and be in continual contact with the outer race of the test bearing. The housing shall be fitted with lugs to accommodate a yoke and added weight so that a radial load may be applied to the test bearing. A thrust load of 22 +/- 2 N (5 +/- 0.55 lbf) shall be applied to the outer race of the bearing by means of a helical spring calibrated at room temperature.

5.3 Motor Drive Assembly - Spindle bracket and constant belt tension motor drive assembly capable of providing spindle speeds up to 10 000 +/- 200 rpm by means of an endless belt. The motor shall be mounted so that a belt tension of approximately 67 N (15 lbf) can be maintained on the test spindle pulley.

5.4 Oven, removable, capable of producing a test temperature of 371°C (700°F) within 1 1/2 h.

5.5 Control Equipment:
5.5.1 The temperature at the outside diameter of the test bearing shall be maintained within 3°C (5°F) of the specified test temperature. The temperature control equipment shall be adequate to maintain the temperature at the outer race of the test bearing within the limits specified by control of the oven temperature. The oven temperature shall be controlled by means of a thermocouple placed in the oven cavity.

5.5.2 Suitable equipment such as adjustable reset relay and overload device for shutting off oven heaters and drive motor and other accessory equipment (timer, recorder, etc.) shall be provided. Oven temperature as well as bearing temperature should be recorded.

6. Materials
6.1 Test Bearing, SAE No. 204 size, fabricated from heat-resistant steel, suitable for temperatures as high as 371°C (700°F). The bearing shall be manufactured to ABEC-3 quality, having a radial clearance of from 0.025 to 0.031 mm (0.0010 to 0.0012 in.). See Annex A1 which describes ABMA's standard method of measuring radial internal clearances of ball bearings. The bearing shall be equipped with a ball retainer fabricated from suitable material capable of withstanding temperatures as high as 371°C (700°F). Support bearings of CRC Type spindles shall be identical to the test bearings.

NOTE 2 - Bearings fabricated from 18-4-1 high speed or M-10 tool steel with retainers fabricated from heat-treated silver-plated beryllium copper have been found satisfactory for this purpose. Alternatively, for testing at temperatures of 149°C (300°F) and below, ASTM Test Bearings Size 6204 (PCN 12-433360-12) ABEC-3 has been found satisfactory. This bearing is fabricated from AISI 52100 steel, with a retainer fabricated from AISI C1010 steel and with an internal clearance range of 0.021 to 0.028 mm (0.0008 to 0.0011 in.).

6.2 ASTM n-Heptane.

NOTE 3 - Warning: Flammable. Harmful if inhaled.

6.3 Stoddard Solvent, conforming to Specification D235.

NOTE 4 - Warning: Combustible. Vapor harmful.