C.
The wheel turns on two roller bearings. One is installed in the hub of the outer wheel half and one in the hub of the inner wheel half. Grease seals over each bearing prevent the grease from leaking out and dirt from getting in. The bearings and grease seals are held in the wheel with retaining rings that allow the bearings and grease seals to come off with the wheel when the wheel is removed from the axle.
(1)
On some B.F. Goodrich wheels a grease dam is installed to help keep the grease on the bearings. There is no maintenance necessary for these grease dams.
D.
Rotor drive keys on the inner wheel half engage slots in the rotors of the disk brakes to allow the rotors to turn with the wheel.
E.
A one piece heat shield installed on the inside surface of the inner wheel half prevents brake heat from damaging the wheel or tire.
F.
Three thermal relief plugs are installed in the tube well of the wheel near the tie bolt area. These plugs sense wheel temperature and prevent failure of the wheel and/or tire because of overheating. The core of the plug contains a fusible metal that melts at a set temperature which then releases the pressure in the tire.
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A
747-400
MAINTENANCE MANUAL
OUTER WHEEL
INNER WHEEL HALF
HALF
TIE BOLT
INNER
WHEEL
BEARING
SEE A
OUTER
WHEEL
BEARING
ROTORDRIVE KEY
HEAT SHIELD
B.F. GOODRICH WHEEL
Wheel Assembly Figure 1 (Sheet 1)
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A
747-400
MAINTENANCE MANUAL
Wheel Assembly
Figure 1 (Sheet 2)
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747-400
MAINTENANCE MANUAL
3. Wheel/Tire Installation (Fig. 2)
_______________________
A. The wheel is assembled with the tire to make a wheel/tire assembly. This is installed on the axle sleeve. The axle sleeve is installed over the axle (interference fit) and has a pin installed through the sleeve and axle to prevent sleeve migration. The inside and outside bearing of the wheel are put in position over machined surfaces of the sleeve. The wheel assembly is tightened into position by an axle nut.
B. The hubcap for the main gear is installed over the end of the axle and is held to the wheel with a clamp. The nose gear hubcap is held to the wheel with three bolts.
C. The hubcap is installed over the end of the axle and held to the wheel with a clamp.
D. On the nose gear a guide block is installed in the end of the axle and attached with the lock bolts that hold the axle nut. The guide block contains a hole which engages with an alignment shaft in the hubcap. The alignment shaft and guide block show when an incorrect wheel bearing is installed in the outside half of the wheel. If the incorrect wheel bearing is installed, the wheel will be pushed out of alignment on the axle when the weight of the airplane is on wheel. This will prevent the hubcap from aligning with mating holes on the wheel when the alignment shaft engages with the guide block.
4. Nose Wheel Snubber (Fig. 3)
__________________
A. Two wheel snubbers are installed in the nose-gear-wheel well. These stop the nose wheels from turning after the gear is retracted. Two snubber blocks, one for each wheel, are installed on metal springs which attach to the wheel well ceiling. When the gear is retracted the wheels are pushed up against the snubber blocks and held against the snubber blocks by the pressure of the springs. The friction between the tire and the snubber blocks stops the wheels from turning.
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