HYDRAULIC
RETRACT FLOW
LINEEXTEND
CONTROL TEE
LINE
SOLENOID ELECTRICAL CONNECTOR
SOLENOID VALVE
FWD
A
Directional Control Valve and Flow Control T-Fittings Figure 2 (Sheet 3)
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. AIRPLANES WITHOUT ONE-WAY VALVE ú
78-34-00
RESTRICTORS ú
ú N03 ú BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details. Page 9Jun 10/95
////////////////////////A / PW4000 SERIES /747-400 / ENGINES /MAINTENANCE MANUAL ////////////////////////
RETURN RETURN
EXTEND EXTEND
PRESSURE RETRACT PRESSURE RETRACT
SOLENOID VALVE SOLENOID VALVE
RETRACT MODE SOLENOID EXTEND MODE SOLENOID DE-ENERGIZED, NORMAL
ENERGIZED, OPERATING DIRECTIONAL CONTROL VALVE
RETURN (RTN) (TO ISOLATION VALVE)
TO LEFT
AND RIGHT
EXTEND (EXT) CENTER SLEEVE
LOCKING
HYDRAULIC
PRESSURE ACTUATORS
(FROM
ISOLATION
VALVE) RETRACT
(RET) EXTEND FLOW CONTROL TEE
TO LEFT
DIRECTIONAL CONTROL AND RIGHT
VALVE SLEEVE
UPPER
SOLENOID NON-LOCKING
VALVE HYDRAULIC
ACTUATORS
RETRACT FLOW CONTROL TEE
Directional Control Valve and Flow Control T-Fittings
Figure 2 (Sheet 4)
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. AIRPLANES WITHOUT ONE-WAY VALVE ú
78-34-00
RESTRICTORS ú
ú N03 ú BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details. Page 10Jun 10/95
B. AIRPLANES WITHOUT ONE-WAY VALVE RESTRICTORS; the system consists of a extend restrictor tee and a retract restrictor tee. The extend restrictor tee contains flow restrictors and a check valve in parallel for each reverser half. The retract restrictor tee contains only flow restrictors.
C. AIRPLANES WITH ONE-WAY VALVE RESTRICTORS; the system consists of an extend and a retract flow control tee assembly. Each assembly contains one-way valve restrictors. If the inner seal of the actuator(s) becomes damaged, the one-way valve restrictors prevent the build-up of deploy pressure when the thrust reverser is commanded to stow or has an auto-restow event.
D. During reverser extension, hydraulic pressure is routed through both extend and retract flow control tees. During reverser retract, hydraulic pressure is routed only through the retract flow control tee. The extend flow control tee is connected to hydraulic system return through the DCV and isolation valve.
6. Thrust Reverser Control Switches and Directional Control Valve Switches_______________________________________________________________________ (Fig. 3)________
A. The thrust reverser control switches (S101, S102, S103, and S104) are found in the housings on each forward thrust lever. Each control switch is closed with a cam to energize its related isolation valve when the reverse thrust lever moves up 10 degrees. The electrical path for each control switch is in series with the fire switch and the air/ground relay.
B. The directional control valve (DCV) switches (S181, S182, S183, and S184) are found in the microswitch pack, which is in the control stand below the thrust levers (Ref 76-11-03/201). Each DCV switch is closed with a cam to energize its related directional control valve when the thrust lever moves up 30 degrees. The electrical path for each DCV switch is in series with the fire switch and the air/ground relay.
7. Proximity Sensor for the Auto Restow of the Thrust Reverser (Fig. 4)___________________________________________________________
A. The proximity sensors for the auto restow of the thrust reverser (S1604,S1605) are found on the aft side of the torque box for the thrust reverser below each center locking hydraulic actuator on each reverser sleeve.
B. When the sleeve is translated aft from the stowed position, the target is moved out of range of the sensor resulting in a "target far" condition at the proximity switch electronic unit (PSEU).
C. The PSEU provides a ground to energize T/R STOW relay ( R7311, R7312, R7313, R7314 ) which closes the auto restow circuit to the isolation valve which provides hydraulic power to the thrust reverser for stowage. Once the thrust reverser is stowed, a 5 second time delay in the PSEU cuts electrical power to the T/R STOW relay which cuts power to the isolation valve. The 5 second time delay ensures hydraulic power is availiable to stow reverser.
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