B. The flex shafts provide synchronization between the actuators. The
tendency of any actuator to speed up or slow down is transmitted to the
others by the flex shafts.
C. The flex shafts are encased in a rigid steel tube, which contains
hydraulic fluid. The hydraulic fluid lubricates the flex shafts.
D. The tubing conducts extend pressure flow between the center actuator and
upper and lower actuators. The tubing enables hydraulic pressure to be
equal in all actuators to permit extension at the same rate.
E. The flex shafts are attached in each actuator through a square drive
fitting.
SYNC SHAFT
Rotary Flex Shafts and Tubing Figure 5
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F. There is no mechanical connection used to provide synchronization between each thrust reverser half, but the flow control valve synchronizes the thrust reverser halves to within three seconds of each other.
8. Thrust Reverser Sync Lock
_________________________
A. The sync lock is an electrically operated mechanical lock installed on the worm shaft of the upper hydraulic actuator on each thrust reverser sleeve. When de-energized, the sync lock holds the rotary flex shafts to prevent the linear movement of the hydraulic actuators.
B. The sync lock contains a pronged rotor which is turned by the rotary flex shaft system. The rotor is held by plungers that engage the rotor. The plungers are spring loaded to the locked position, and are moved to the unlocked position by a solenoid operated yoke when energized.
9. Fan Duct Cowl and Thrust Reverser Opening Actuator
__________________________________________________
A. Cowl/reverser opening and closing is accomplished with a cowl opening actuator. The fan cowl panels must be opened before opening the cowl/reverser.
B. The opening actuator is attached at the upper end to the thrust reverser cowl half and at the lower end to the engine fan frame extension ring.
C. Power for opening the cowl/reverser halves is provided by a hand-operated pump.
10. Operation
_________
A. Functional Description
(1) Extension
(a)
Reverse thrust is selected by moving the forward thrust lever to idle and lifting the reverse thrust lever to select reverse thrust. Further rearward movement of the reverse thrust lever increases power in the reverse thrust range. Following initial selection, however, movement of the reverse lever beyond reverse idle is restricted by the balk mechanism until the system reaches mid-travel position. Thereafter the balk is removed progressively, allowing power to be increased.
(b)
Operation of the reverse thrust lever closes contacts in the selector switch, completing a circuit through the air/ground relay to energize the isolation valve solenoid. The solenoid valve opens to admit hydraulic fluid on to the isolation valve, and the valve opens.
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(c)
Operation of the reverse thrust lever closes the contacts on a microswitch in the autothrottle switch pack and sends power to a latch relay which energizes the sync lock solenoid to release the rotary flex shaft system.
(d)
The directional control valve is mechanically repositioned by the initial movement of the reverse thrust lever to direct hydraulic fluid, at approximately 300 psi, through the extend and retract tubes on to both sides of the actuator pistons. The hydraulic pressure is equal on both sides but area differential across the piston produces piston movement in the extend direction.
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