Figure 14-10.--Exploded view of single disc brake assembly.
the housing contains a piston, a return spring, and an
When pressure is relieved, the force of the return
spring is sufficient to move the piston away from the
automatic adjusting pin.
brake disc, but it is not enough to move the adjusting
There are six brake linings (pucks), three on the
pin, which is held by the friction of the pin grip. The
inboard side of the rotating disc and three on the
piston moves away from the disc until it stops against
outboard side of the rotating disc. These brake linings
the head of the adjusting pin, which provides a preset
are often referred to as "pucks." The outboard lining
clearance between the pucks and the disc. The
pucks are attached to the three pistons, and they move
self-adjusting feature of the brake will maintain the
in and out of the three cylinders when the brakes are
desired puck-to-disc clearance, regardless of lining
operated. The inboard lining pucks are mounted in
wear. Thus, regardless of the amount of wear, the same
recesses in the brake housing and are stationary.
travel of the piston will be required to apply the brake.
Hydraulic pressure from the brake control unit
Maintenance of the single disc brake may include
enters the brake cylinders and forces the pistons and
bleeding, performing operational checks, checking
lining wear, checking disc wear, and replacing worn
their pucks against the rotating disc. At the same time,
linings and discs.
the piston pushes against the adjusting pin (through the
spring guide) and moves the pin inboard against the
A bleeder valve is provided on the brake housing
(fig. 14-10) for bleeding the single disc brake.
Bleeding should be performed according to the
The rotating disc is keyed to the landing gear wheel
instructions contained in the aircraft MIM.
so that it is free to move laterally within the brake
cavity of the wheel. Thus, the rotating disc is forced
Operational checks are made during taxiing.
into contact with the inboard pucks mounted in the
Braking action for each main landing gear wheel
housing. This lateral movement of the rotating disc
should be equal, with equal application of pedal
pressure and without any evidence of soft or spongy
ensures equal braking action on both sides of the disc.