1. Brake disc
2. Lining puck
3. Adjusting pin nut
4. Cylinder head
5. O-ring gasket
6. O-ring packing
Adjusting pin grip
13. Brake return spring
14. Adjusting pin
15. Bleeder screw
Internal retainer ring
17. Bleeder valve
18. Bleeder adapter
Figure 12-31.-Exploded view of single disc brake assembly.
20. Fluid inlet bushing
24. Brake housing
Figure 12-31 shows an exploded view of a typical
The rotating disc is keyed to the landing gear wheel
single disc brake assembly. This brake assembly has a
three-cylinder, one-piece housing. Each cylinder in the
housing contains a piston, a return spring, and an
automatic adjusting pin.
There are six brake linings (pucks), three on the
inboard side of the rotating disc and three on the
outboard side of the rotating disc. These brake linings
are often referred to as pucks. The outboard lining
pucks are attached to the three pistons, and they move
in and out of the three cylinders when the brakes are
operated. The inboard lining pucks are mounted in
recesses in the brake housing and are stationary.
Hydraulic pressure from the brake control unit
enters the brake cylinders and forces the pistons and
their pucks against the rotating disc. At the same time,
the piston pushes against the adjusting pin (through the
spring guide) and moves the pin inboard against the
friction of the adjusting pin grip.
so that it is free to move laterally within the brake cavity
of the wheel. Thus, the rotating disc is forced into
contact with the inboard pucks mounted in the housing.
This lateral movement of the rotating disc ensures equal
braking action on both sides of the disc.
When pressure is relieved, the force of the return
spring is sufficient to move the piston away from the
brake disc, but it is not enough to move the adjusting
pin, which is held by the friction of the pin grip. The
piston moves away from the disc until it stops against
the head of the adjusting pin, which provides a preset
clearance between the pucks and the disc. The
self-adjusting feature of the brake will maintain the
desired puck-to-disc clearance, regardless of lining
wear. Thus, regardless of the amount of wear, the same
travel of the piston will be required to apply the brake.
Maintenance of the single disc brake may include
bleeding, performing operational checks, checking