RETRACT LINE FLEX HOSE
GIMBAL RING
UPPER RETRACT
HYDRAULIC LINE
GIMBAL RING
RETAINER

TORQUE BOX
UPPER NON-LOCKING HYDRAULIC ACTUATOR
C
Thrust Reverser Hydraulic Actuation System
Figure 8 (Sheet 2)

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
////////////////////////A / PW4000 SERIES /747-400 / ENGINES/MAINTENANCE MANUAL ////////////////////////
G.  Fluid flow to and from the rod end cavity goes through a port to the snubbing ring. When the hydraulic actuator extends, outflow goes to the hydraulic fluid fitting on the actuator rod end. Snubbing starts at 20.6 inches of extend travel when the snubbing skirt on the piston rod goes between the piston rod and the snubbing ring. Due to the restricted fluid flow passage, pressure on the retract side of the piston will increase as the hydraulic actuator slows in speed. Snubber performance is made to stop the hydraulic actuator motion in approximately one inch of travel. The reverser retract cycle is not snubbed because the retracting velocities are lower and there are no driving aerodynamic loads.
 H.  Each hydraulic actuator is gimbal mounted to the front torque box structure of the thrust reverser, and attached to the translating sleeve with a spherical rod end bearing and clevis. The center hydraulic actuator of each translating sleeve includes the locking device that locks the actuation system in the stowed position, and the reverser position feedback linear variable differential transformer (LVDT).
 I.  A 3/8 inch manual crank (drive) adapter is attached to each lower hydraulic actuator for manual actuation of the thrust reverser.
 10. Locking Hydraulic Actuator (Fig. 9)
__________________________
 A.  Each half of the translating sleeve for each thrust reverser is moved with three hydraulic linear actuators. The center hydraulic actuator on each half includes a locking mechanism that functions by engagement of two serrated disks. This engagement directly prevents rotation of the flexshaft that mechanically interconnects the three hydraulic actuators.
 B.  One disk is keyed to the acme screw in the hydraulic actuator and turns when the hydraulic actuator moves. The other disk is nonrotating, splined to the actuator barrel, and operates linearly along the spline by a helical spring to engage the two disks, and by the locking piston through the lock lever pivot arm to move the two disks apart.
 C.  When thrust reverser extension is commanded, hydraulic pressure buildup causes the lock piston to move to engage the pivot arm of the lock lever. Once engaged, further motion moves the nonrotating lock disk apart from the rotatable disk. Continued motion of the lock piston ports hydraulic fluid through an orifice directly to the head end of the center hydraulic actuator and through connecting flexshaft tubing to the head ends of the two non-locking hydraulic actuators, which causes thrust reverser extension. As the head end of the center hydraulic actuator moves away from the stowed position, compression of the helical lock spring is relaxed which lets the splined serrated disk to be held away from the rotating disk by the torsion lock spring on the pivot arm of the lock lever. The orifice makes sure that hydraulic pressure is available to hold the lock piston in the unlocked position under all operating load conditions during the thrust reverser extension.
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 ALL  ú ú N01 Page 18 ú Jun 10/96
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
SEE A
FEEDBACK LVDT ELECTRICAL CONNECTORS
SEE A  RETAINER GIMBAL RING  DRIVESHAFT UPPER FLEXIBLE HYDRAULIC LINE UPPER RETRACT 
TUBENUT HYDRAULIC LINE EXTEND LOCK LEVER 
HYDRAULIC LINE LOWER RETRACT  TUBENUT  B PROXIMITY SENSOR ACTUATOR LOCK SEE 
FWD  DRIVESHAFT LOWER FLEXIBLE  ACTUATOR HYDRAULIC LOCKING 
A 
FEEDBACK LVDT  PROXIMITY SENSOR ACTUATOR LOCK 
LOCK LEVER 
SENSOR DEPLOY PROXIMITY  B  WIRE CLAMPS  WIRING PROXIMITY SENSOR 
　
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