Figure 12-62.—Air refueling probe hydraulic system.
circuit to energize solenoid A of the launch bar selector
valve. The energized selector valve directs hydraulic
system pressure to the launch bar actuating cylinder
extend port. Hydraulic pressure unlocks locking fingers
in the launch bar actuating cylinder and extends the
actuator rod end. The actuator rod end is attached to the
launch bar, and as the actuator extends, it lowers the
launch bar. As the launch bar moves down, it encloses
two horns on the nose gear axle beam, enabling the
launch bar to steer the nose gear.
Before the airplane reaches the catapult, the tension
and holdback bars are attached to the tension bar socket.
As the airplane approaches the catapult, the launch bar
enters a track that permits the bar to steer the nose gear
for alignment with the catapult.
The top of the launch bar actuating cylinder is
gimbal-mounted to permit rotation in all directions as
the launch bar turns and is raised and lowered. As the
airplane moves forward, aligned with the catapult, the
launch bar automatically engages the catapult shuttle.
The shuttle is advanced to tension the airplane on the
catapult.
The launch bar switch is placed in OFF, de-
energizing the selector valve. When catapult pressure
reaches a predetermined value the tension bar breaks
and the airplane is catapulted off the deck.
In the de-energized position, the selector valve
connects the launch bar actuator extend and retract ports
to the hydraulic return circuit. The launch bar is held in
the down position by the catapult shuttle until reaching
the end of the launch run, where the bar is released from
the shuttle and the weight-on-gear switch is actuated to
the weight-off-gear position. When the switch is
activated to the weight-off-gear position, a power circuit
is completed to energize the retract solenoid of the
launch bar selector valve. The energized valve directs
hydraulic pressure to retract the launch bar actuating
cylinder, automatically retracting and locking the
launch bar. Two leaf springs on each side of the launch
bar shank raise the launch bar to the retracted position
if automatic hydraulic retraction fails. When the piston
is fully retracted locking fingers on the piston lock the
actuator and launch bar in the retracted position.
Hydraulic retraction of the launch bar is obtained by
holding the launch bar control switch in RETRACT.
This action completes an electrical circuit to energize
the launch bar selector valve retract solenoid (solenoid
B). The energized selector valve directs hydraulic
pressure to retract the launch bar actuator. The actuator
retracts, pulling the launch bar up and locking the
actuator and launch bar in the retracted position.
IN-FLIGHT REFUELING SYSTEMS
Air refueling systems permit complete in-flight or
on the ground refueling of the aircraft fuel system. The
refueling probe extension and retraction system shown
in figure 12-62 consists of the refueling probe, refueling
nozzle, a self-locking, two-position probe actuating
cylinder, a lock swivel joint, two restrictor valves, a
selector valve, and associated electrical switches and
relays.
12-70
