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 TM 5-685/NAVFAC MO-912
LUBE OIL
WATER INLET
LUBE OIL
FILTER
ERATURE
WATER OUT
LUBE OIL OUT
SUMP
Figure 3-9. Diesel engine lubrication system.
comes up to speed and the auxiliary pump is shut
sible. Also, the coils may be placed in the side jack-
down. The check valve also prevents loss of oil in
ets. Some designs have the coil tubes in the cooling
case of leakage.
water header, while in others, water entering the
cooler is bypassed around the jacket system.
i. Oil filters. Proper installation and maintenance
heat from the engine. Frictional heat is absorbed
from the bearings. The oil film on the cylinder walls
of oil filters and mechanical operation of the engine
absorbs heat from the combustion space before this
are equally important for treatment of oil. Preven-
oil film drains into the crankcase. Heat must be
tion of contamination and removal of contaminants
should be coordinated. Because high-detergent oils
dissipated by a cooler if the temperature is to be
Fahrenheit. At higher tempera-
are used in engines, the purification system should
kept below
tures, oil oxidizes and sludge forms. An oil cooler is
not remove the additive. Cellulose filter cartridges
necessary when heat dissipated from the oil (by
do not remove the additive, but a fuller's earth filter
conduction through the walls of the sump and by
does. In large engine installations, a centrifuge may
contact with water-cooled surfaces in the engine) is
be used with filter purifiers, or large continuous oil
insufficient to keep the temperature below manu-
purifiers may be used in lieu of the centrifuge. Cen-
facturer's recommendations. A cooler is particularly
trifuging does not remove acids because acidic com-
necessary for engines having oil-cooled pistons.
pounds have approximately the same specific grav-
h. Coolers. The oil cooler should be placed in the
ity as oil. Batch settling effectively removes organic
oil circuit after the lubricating oil filter. The filter
acids from oil, improving its neutralization number.
then handles hot oil of lower viscosity than if it
When purifiers are used, they should be used in
received cooled oil. The filter performance is better
addition to, not in place of, lube oil filters.
and the pressure drop through it is less with this
3-7. Starting system.
arrangement. Coolers are usually mounted on the
side of the engine or on the floor alongside of the
The starting system for diesel engines described in
engine base. Cooling water passes through the
this manual must perform as follows for automatic
cooler before entering the engine jackets. Excep-
start-up when primary electric power fails: com-
tions, such as placing the oil-cooling coils in the
press the air in the combustion chambers and de-
water jackets at one end of the engine, are permis-
liver fuel for combustion. To do this, the starting
3-15
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