TM55-2840-251-23
Section III PRINCIPLES OF OPERATION (Continued)
1-12 LUBRICATION SYSTEM
The lubrication system is designed to provide a constant
supply of oil to cool and lubricate bearing surfaces of the
engine and conduct debris to the oil filter. Oil pressure
and temperature is measured by transmitters mounted
on the accessory gearbox. Oil is drawn from the integral
oil tank in the accessory gearbox by gear type pump and
delivered under pressure to oil jets directed at bearings
and gearshafts. Oil pressure is regulated by a relief
valve situated in the inlet case.
Scavenge oil drainage from bearings and gearshafts is
delivered by scavenge pumps to the oil tank, by way of
the oil cooler.
Breather air from bearing compartments and gearboxes
is vented through a centrifugal breather located in the
accessory
gearbox.
Accessory
gearbox
internal
pressure
is
normally
higher
than
atmosphere,
consequently, oil vapor in the gearbox tends to escape
to atmosphere through the hollow gearshaft. Centrifugal
action separates oil and air; the air passes, via the vent
shaft, to the atmosphere and air-free oil is sprayed out
to drain to the bottom of the gearbox to be scavenged.
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