TM 1-1520-238-T-4
3–8
3–2.
LOCATION AND DESCRIPTION OF MAJOR COMPONENTS (cont)
3–2
(6) Tail Wheel Lock Actuator System.
The tail wheel lock actuator system (fig. 3–8) consists of an
actuator, a lock/unlock handle, a proximity switch and a tail wheel lock control valve. The tail wheel lock actuator
is mounted to the trailing arm housing and is spring loaded to the locked position and controlled by the tail wheel
UNLOCK/LOCK switch on the pilot’s TAIL WHEEL panel. A handle on the lock actuator allows the ground crew
to manually operate the actuator. The lock/unlock handle is held in the locked and unlocked position by two
springs attached on each side of the handle and the tail wheel lock actuator. The underside of the lock handle
contains an adjustable bolt to set the handle mechanism to prevent it from automatically returning to the full up
position. The proximity switch, an electrically controlled and magnetically operated sensor, informs the pilot of
current actuator position. The proximity switch mounts to the upper portion of the lock actuator and works in
conjunction with the lock target installed in the upper end of the lock actuator. The tail wheel lock control valve is
energized when the pilot’s TAIL WHEEL switch is placed in the UNLOCK position and allows hydraulic fluid to be
sent to the actuator.
c. MLG Brake System.
The MLG brake system (fig. 3–9) consists of two pilot master cylinders, two CPG
master cylinders, two transfer valves, a parking brake valve, two wheel brake assemblies and two brake discs.
The MLG brake system is mounted on the inboard side of each wheel and tire assembly.
(1) Master Cylinder.
A master cylinder (fig. 3–10) is attached to each of the four directional control
pedals (rod end bearing) and the directional control pedal mounting bracket (end cap bearing). The master
cylinders transfer force applied by a crewmember’s foot, into fliud pressure. The master cylinders apply hydraulic
fliud pressure to other brake system components and also serve as hydraulic fliud reservoirs.
(2) Transfer Valves.
Two transfer valves (fig. 3–9) are mounted on a bracket between the pilot’s
directional control pedals and the pilot’s forward, lower console structure. Each valve has a bleed valve, an output
pressure port (to attach a brake line from the valve to the each park brake valve), an input port (to attach a brake
line from the valve to the pilot master cylinders), and an input port (to attach a brake line from the valve to the
CPG master cylinders). The major internal components of the transfer valves are a piston valve, a poppet valve
and 2 springs.
(3) Parking Brake Valve.
The parking brake valve, secured to a bracket assembly forward and below
the transfer valves, consists of a control lever and cam, a handle, two compensators and two bleed valves. The
parking brake valve body has two inlet pressure ports which receive pressure from the transfer valves. Two outlet
pressure ports provide fluid pressure to the wheel brake assemblies. A cam shaft assembly positions four internal
valves. The control lever is installed at one end of the cam shaft to rotate the shaft and set the park brake. A
return spring is attached to one end of the lever and the transfer valve mounting bracket. The parking brake
handle assembly is in the pilot station and is connected via a flexible steel wire cable to an adjustable clevis in the
brake lever. Two compensators and two bleed valves are installed at the pilot center console panels. The bleed
valves are connected via tubing to the bleed ports at the parking brake valve.
(4) Wheel Brake Assembly and Brake Disc.
The wheel brake assembly (fig. 3–11) is bolted to each
MLG flange at the inboard portion of the trailing arm axle. Brake discs are attached to the wheel and tire
assemblies. The wheel brake assembly (2 each) consists of a brake housing, a pressure inlet port and a bleed
port. Each brake disc has eight key slots which mount over eight corresponding keys on the wheel rim. The brake
housing mounts to a flange on the axle. The brake disc rotates between the friction linings in the brake housing.
