a shaft, a pair of bevel gears, bearings, and oil
casing, an air/oil separator, gears, bearings,
jets (not shown). Two duplex ball bearings and
seals, oil nozzles, and accessory adapters. The
a roller bearing are mounted in the casing. The
accessories are the fuel pump, main fuel control
casing is bolted inside the front frame hub and
(MFC), lube and scavenge pump, air/oil
has internal oil passages and jets to provide
separator, and starter. All except the air/oil
separator are mounted on the aft section (fig.
which rotates on a horizontal axis, is splined at
2-35, view B). The aft section of the TGB is
the aft end to mate with the second-stage disk of
the AGB. An access cover in the bottom of the
the compressor rotor. The forward end of the
casing allows easy removal and installation of
shaft mounts the upper bevel gear and is
the radial drive shaft. Also, an access cover is on
supported by a duplex ball bearing. The lower
the manual drive pad. This feature allows access
bevel gear rotates on a vertical axis. It is supported
to the jacking gears, which you can use to
at its upper end by a roller bearing and at its lower
manually jack the engine over for maintenance.
end by a duplex ball bearing. The lower end is
The "plug-in" gear concept is used on all
also splined to mate with the radial drive shaft.
accessory adapters and idler gears in the aft
section. This concept permits an entire gear,
RADIAL DRIVE SHAFT.--The radial drive
bearing, seal, and adapter assembly to be removed
shaft, a hollow shaft externally splined on each
and replaced without disassembling the gearbox.
end, mates with the bevel gears in the inlet and
Each spur gear is supported by a casing-mounted
transfer gearboxes. Its function is to transmit
roller bearing on one end and an adapter-mounted
power from the inlet gearbox to the forward
ball bearing on the other end. The accessory drive
section (bevel gearbox) of the TGB. The shaft con-
spur gears are internally splined. Internal tubes
tains a shear section (for overtorque protection)
and oil nozzles provide lubrication of the gears
to prevent damage to the accessory drive system.
and bearings. Gearbox carbon-face seals are
retained from the outside of the gearbox. You can
POWER TURBINE/LOW-PRESSURE
replace them without disassembly of the gearbox.
SECTION
The TGB is assembled as a single unit and bolted
to the engine externally. This feature allows you
The PT is used to extract the remaining energy
to replace the entire unit without removing the
from the hot gas. This energy is used to power
engine from the enclosure.
the ship for propulsion. The PT section (fig. 2-37)
has a six-stage LP turbine rotor, a turbine stator,
INLET GEAR BOX.--The inlet gearbox
and a rear frame. The PT is a separate unit from
assembly (fig. 2-36) has a cast aluminum casing,
Figure 2-37.--LM2500 GTE power turbine.
Figure 2-36.--Inlet gearbox.
2-30
