From the boss, the oil is directed internally, via cored passages and transfer
tubes, to three areas.
1. First, to the rst-stage reduction gears, the torquemeter, and the No. 3
and 4 bearings. Oil to the torquemeter ows through a metering valve
which controls the ow into the torquemeter chamber. The position of the
metering valve is controlled by the torquemeter piston which reacts in direct
proportion to engine torque. Oil is directed to three nozzles in the No. 3
bearing oil tube, in the power turbine shaft housing, via a transfer tube in
the rear case of the reduction gearbox. Two nozzles direct oil to the front
and rear faces of the No. 3 roller bearing, while the third nozzle directs the
oil ow to the rear face of the No. 4 bearing.
2. The second oil delivery line directs oil to the propeller shaft front roller
and ball thrust bearings, the second-stage reduction gears and the No.
4 bearing. The oil ow is directed through the rear annulus of an oil
transfer sleeve mounted on the propeller shaft and, via the rear section of
the propeller oil transfer tube in the shaft, to the No. 4 bearing oil nozzle
installed at the rear end of the transfer tube. The oil is sprayed into the
hollow front section of the power turbine shaft; centrifugal force directs
the oil through a drilled annulus in the shaft to passages between the No.
4 bearing inner races and into the sun gear coupling. Oil from the rear
section of the propeller shaft oil transfer tube is also directed, via drilled
holes in the propeller shaft and cored passages in the second-stage gear
carrier, to the shaft/second-stage gear-pins and propeller shaft roller
bearing.
3. The third oil delivery line directs oil via an internal annulus and cored
passages to the externally mounted propeller governor, the accessory drive
gears and the propeller thrust bearing. Oil pressure from the propeller
governor is directed via a port in the mounting ange and cored passages
in the front case of the reduction gearbox to a transfer tube which connects
to the front annulus in the oil transfer sleeve mounted on the propeller
shaft. The oil in the annulus is then directed into the propeller shaft center-
bore via the front section of the propeller oil transfer tube.
Scavenge Oil System
The scavenge system incorporates two double-element gear-type pumps
contained in cast housings, and are driven by the accessory gearbox
driveshafts. One pump is mounted within the accessory gearbox, while the
other is externally mounted at the rear of the gearbox. Oil from the No. 1
bearing compartment is returned by gravity via an internal cored passage to
the bottom of the compressor inlet case. From there, it is directed through
the oil tank compartment by a transfer tube and a port in the accessory
diaphragm and is then discharged into the gearbox. The No. 2 bearing
oil drains via internal tubes to a boss at the 5 o’clock position on the gas
generator case. A anged transfer tube directs the oil rearward to a boss
at the 6 o’clock position on the compressor inlet case; the oil then passes
through cored passages and a transfer tube to the front element of the
internal scavenge pump. Scavenged oil is dumped into the accessory