FED-STD-791D
a. Viscosity
b. Carbon residue
c. Total acid
6.2 Subject the oil to endurance test as follows:
a. Drain any old oil remaining in the system; remove sump and wipe clean with
lintless wiping cloths and naphtha; remove bearing caps, bearings, and shaft
from machine; wipe shaft with lintless wiping cloths and naphtha to remove
stains.
b. Spread film of test oil on journal and three sets of new bearings; install the shaft
and bearings; use a torque of 115-129 N.m (85-95 lb-ft) on bearing cap bolts.
c. Flush run. Temporarily install a 10 micrometer filter between the oil sump and
pump inlet. (Filter should be a clean or new filter.) Place approximately 3 L (3
qt) of the test oil in sump. Start pump and turn on sump heater, and slowly
adjust oil flow to 1.9-2.3 L/min (0.5-0.6 gpm) (to avoid excess oil pressures).
Start motor at 1750 rpm. Allow system to operate for 30 min. During the last
10 min apply a load (half that specified for test) to check out the system
functioning. Shut down the machine by first unloading the bearing and then
stopping the motor drive. Shut off the oil pump and heater. Drain all oil from
the system and wipe sump clean with lint-less wiping cloths. Remove the oil
filter from the system and install direct connect from pump inlet to sump.
NOTE 3.
A single flush run, following the above procedure, will usually provide
sufficient system cleaning.
d. Test oil. Place 4 L (l gal) of test oil in clean sump and start heater. Start oil
pump and adjust flow with bypass valve to give 1.9-2.3 L/min (0.5-0.6 gpm).
Start motor drive at speed of 3500 rpm and gradually load bearing (using 2 or 3
min.) with loading device to yield a load of 1517 gage kPa (220 psig) of
projected bearing area. As the system temperature comes to equilibrium, adjust
sump temperature controller to give a bearing temperature of 138 0.5C
(280 1F) which shall be maintained during the test. Operate the machine
under these conditions for a period of 200 h. During this time continuously
record bearing temperature, temperature of oil supply to bearing, and
temperature of oil in sump. Observe and record (daily) oil flow rate and oil
pressure to bearings. Oil flow rate to bearings shall be adjusted during test
period to maintain 1.9-2.3 L/min (0.5-0.6 gpm) to bearings.
6.3 Inspection of bearings at end of 200-hour endurance test. Dismantle all
journal bearings and rinse in naphtha. Observe bearing surfaces for evidence of deposits,
corrosion, wiping, or other changes. Particular reference is to be made to loaded (center)
bearing. Report the observation for all bearings.
6.4 At the end of the 200 hour endurance test, determine the properties of the
used lubricant, as given in paragraph 6.1.
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