cooled. See figure 7-16. An electromagnetic chip
disconnect jaw permits folding and unfolding of
detector/drain plug is in the bottom of the input
the pylon without manually disconnecting the
housing. It also has an oil level sight gauge and
transmission. A transmission lock prevents the
a filler plug. Access to the tail gearbox is through
rotary rudder from windmilling when the pylon
the tail gearbox access fairing at the top of the
is folded. The lock is automatically unlocked
when the pylon is unfolded (flight position). The
pylon.
input and output housings contain similar bevel
MAIN DRIVE SHAFT
gears to change the angle of drive up along the
pylon. The center housing has an oil level sight
The main drive shaft is a dynamically balanced
gauge. It has a chip detector/drain plug on
the bottom, and the filler plug at the top. See
shaft that transmits torque from the power turbine
figure 7-15. The electromagnetic chip detector, in
to the main gearbox. The SH-3 drive shaft
assembly consists of a high-speed shaft, Thomas
addition to normal chip detector function, also
coupling, engine adapter, and match-marked nuts
detects overheating of the intermediate gearbox.
for engine attachment. The shaft assembly has
The gearbox is splash-lubricated and air cooled.
match-marked bolts and nuts for attachment to
TAIL GEARBOX
the main gearbox coupling. The Thomas coupling
and engine adapter secure to the shaft by special
bolts and hi-lock collars to prevent disassembly.
The tail gearbox, mounted at the top of the
The shaft is made of tubular steel, and it is about
tail pylon, supports and drives the rotary rudder.
13 1/2 inches long. It is flanged at both ends for
It reduces shaft speed and changes the direction
connection to the Thomas coupling, adapter, and
of drive by 90 degrees. A pitch change shaft,
power turbine coupling flange, and to the main
controlled by the rudder flight controls, operates
gearbox coupling flange. The drive shaft is within
a pitch change beam. Linked to the sleeve of
and protected by the aft engine support. The
each rotary rudder blade is a pitch change
direction of shaft rotation is clockwise (when
beam. The gearbox is splash-lubricated and air
Figure 7-16.-Tail gearbox.
Figure 7-15.-Intermediate gearbox.
7-17
