Learjet 60 - Parking Brake; Wheel Brake System

Pilot's Manual
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Learjet 60
WHEEL BRAKE
SYSTEM
The primary
brake system utilizes hydraulic
system pressure for
power boost . Hydraulic
pressure from the nose gear
down line is me-
tered
to the disc-type
wheel brakes by the power
brake valves . The
valves are controlled
by the rudder pedal toe brakes
through mechan-
ical
linkage . Two
shuttle valves in the
pressure lines prevent fluid
feedback
between the
pilot's and copilot's
pedals . Four additional
shuttle
valves connect
the pneumatic system to the
brake system for
emergency braking .
Hydraulic fuses,
located in the main gear wheel
wells, will close to
prevent pressure
loss if fluid flow exceeds
normal
brake actuation
rate . "Snubbing"
of the main gear wheels is
accom-
plished
during retraction by
means of hydraulic back pressure
in the
brake
lines caused by a
restrictor in the return line . An
integral anti-
skid system is installed to
effect maximum braking efficiency .
When
parking, it is advisable
to have the wheels
chocked prior to releasing
brakes .
PARKING BRAKE
The parking brake handle is
labeled PARKING BRAKE and is located
on the pedestal below
the thrust levers . The handle is
mechanically
connected to the parking
brake valve through which all pressure from
the primary brake system must
pass . The parking brake system is ac-
tuated by pressing and
holding the toe brakes (hydraulic system pres-
surized) then pulling the
parking brake handle which closes the park-
ing brake valve, locking
pressure against the wheel brakes . Pulling
the parking brake handle
also closes the solenoid shutoff valve on the
anti-skid system to prevent
leakage through the anti-skid valve . Re-
turning the parking brake handle to the off position releases
the
brakes .
The anti-skid system is inoperative when the parking brake is
engaged .
3- 1 6
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PM-123
Original