ASTM D5706 Standard Test Method for Determining Extreme Pressure Properties of Lubricating Greases Using a High-Frequency, Linear-Oscillation (SRV) Test Machine
8. Preparation of Apparatus
Preparation of SRV I and II Models
8.1 Turn on the test machine and chart recorder and allow to warm up for 15 min prior to running tests.

8.2 Select the friction data to be presented in the crest peak value position in accordance with the manufacturer's directions.

NOTE 4 - In most cases, this is accomplished by positioning the sliding switch on electronic card NO. 291.35.20E (front side of electronics behind the front panel) and the sliding switch located on the back panel of the control unit.

8.3 Turn the amplitude knob to ZERO.

8.4 Switch the stroke adjustment to AUTO position.

8.5 Set the frequency to 50 Hz.

8.6 Set the desired span and calibrate the chart recorder in accordance with the manufacturer's instructions. Select the desired chart speed.

8.7 Turn on the heater control, and preheat the disk holder to the desired temperature. 50 °C, 80 °C, and 120 °C are recommended (see Table 1). When the temperature has stabilized, turn on the chart recorder and depress the drive start toggle switch until the timer begins to count and then adjust the stroke amplitude knob to 2.00 mm.

8.8 Set the load charge amplifier to setting that corresponds to the 400 N load.

8.9 Change the load charge amplifier at each load in accordance with the manufacturer's instructions when the coefficient of friction at each test load is to be studied.

8.10 When the digital timer reaches 30 s, increase the load to 100 N using the slow ramp speed rate, and maintain this load for 15 min.

8.11 The 15 min interval includes the loading ramp sequence. The load has to be increased by 100 N every 2 min using the slow ramp until a load of 1200 N is reached, or the load limit of the test apparatus is attained, or failure occurs. Failure is indicated by a rise in coefficient of friction of greater than 0.2 over steady state for over 20 s or a stoppage in the oscillating of the test machine (see Test Method D5706 or D6425.

NOTE 5 - Because a 30 s break-in at 50 N is used, the load increase times will occur on the half minute of even minutes.

8.12 When the 1200 N load run or maximum load ofthe test apparatus is completed or failure occurs, turn off the heater control, release the load to minimum setting, (typically -13 N or -14 N), and remove the test ball, disk, and lubricating oil test specimen.

Preparation of SRV III, IV, and V Models
8.13 When using SRV III, SRV IV, and SRV V models, clean and install the specimens as specified under 9.1 to 9.7. Turn on the test machine and the PC and allow to warm up for 15 min prior to running tests.

8.14 Create a set point profile in the SRV control software with the following parameters:

NOTE 6 - Depending on the software version, names and availability of the parameters can vary.

8.14.1 Start conditions (thermostatic stabilization):
Temperature: for example, 50 °C +/- 1 K or 80 °C +/- 1 K
Test load: 50 N +/- 1 N
Start delay: 300 s (is displayed by all versions of the SRV software)

8.14.2 Cut-off criteria for friction, if occurs:
Coefficient of friction, f (cut-off value for permanent increase of level):
0.3 during t > 20 s
Coefficient of friction, f (cut-off value for one-off increase of level): 0.35

8.14.3 Test parameters:
Frequency: 50 Hz
Stroke: 1.00 mm for procedure A with 2 min run-in; 1.50 mm for procedure B with 15 min run-in
Temperature: for example, 50 °C or 80 °C
Pre-load: 50 N for 30 s
Test load: running-in under 100 N for 15 min, then steps of 100 N with a duration of 2 min until the maximum test load (usually 2000 N) has been reached.
Total test duration: up to 53.5 min

NOTE 7 - Because a 30 s break-in at 50 N is used, the load increase times will occur on the half minute of even minutes.

NOTE 8 - For optimal comparability with older SRV models I and II, the test load should be set as a ramp function with a gradient of 7.5 N/s.

8.14.4 Sample rates for result-relevant measurement channels:
Coefficient of friction, f: ≤ 32 ms
Stroke: ≤ 2 s
Test load: ≤ 2 s
Frequency: ≤ 2 s
Temperature: ≤ 2 s

After that, apply a load increment of 100 N every 2 min.

NOTE 9 - For SRV V models, it is recommended to do one sampling per period (that is, 20 ms) for coefficient of friction and stroke.