(8)
When the auto restow proximity sensors are out of proximity they complete a circuit to energize the arm valve solenoid and open the isolation valve. The solenoid stays energized as long as the sleeves are translated aft from the stow position and the prox sensors are out of target proximity range.
(9)
The sleeves translate to the full extend position in approximately
2.5 seconds. The blocker doors extend as the sleeves translate to redirect the fan exhaust through the cascade vanes.
(10)
The actuators act as hydraulic brakes with the rate of extension controlled by the rate of flow.
(11)
The piston rods are decelerated and stopped at the full extend position by snubbers, inside the actuators.
(12)
The feedback push-pull cables provide position indication of the center actuator extension and sleeve position to the strut control box.
(a) The feedback interlock cams are repositioned by push-pull cables. Cam positioning allows for increased power setting.
(13)
The reverse thrust levers can now be pulled back and up further to increase power. The reverse thrust lever angle from idle detent to full power is 135.5 degrees.
(14)
Reverse thrust is produced as the fan exhaust is redirected by the blocker doors through the cascade vanes.
C. Stowing
(1)
The reverse thrust levers are pushed forward and down to the stowed position. The reverse thrust lever angle of travel from full reverse to idle is 135.5 degrees.
(2)
The thrust lever latch re-engages.
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CFM56 ENGINES
737-300/400/500/ /MAINTENANCE MANUAL ////////////////////////
(3)
The stow valve repositions the directional control valve, which vents return hydraulic pressure from the extend side of the actuator. The hydraulic system pressure on the retract side of the actuators causes the actuators to retract.
(4)
The flex shafts synchronize the actuator retraction.
(a)
The upper actuator lock remains unlocked until the actuator piston contacts the lock and begins to load the lock spring.
(b)
The face of the lock mechanism has angled teeth causing ratchet-type action as the actuator retracts.
(5)
The isolation valve check valve allows hydraulic fluid at return pressure of 45 psi to return to the aircraft hydraulic system.
(6)
The REVERSER UNLOCKED light remains illuminated until both sleeves are fully stowed as detected by the not-stowed proximity sensors, at which time the light extinguishes.
(7)
The forward thrust levers cannot be moved from idle position until the feedback push-pull cables re-position the feedback interlock cams.
(8)
Power is sent through the microswitch pack to a two minute time delay relay. The two minute time delay permits the thrust reverser to retract which provides time for the indicating system to detect failures that prevent the locking actuator from locking the thrust reverser sleeve in the retracted position. After two minutes, power is sent through the time delay relay to unlatch the latch relay, which then de-energizes the sync lock solenoid. This permits the sync lock to mechanically lock the rotary flex shaft system.
D.
Electrical Control
(1)
To complete circuitry for the thrust reverser deployment, the following conditions must be met:
(a)
28v dc switched hot battery bus power available.
(b)
Fire switch handles in normal position.
(c)
Airplane altitude less than 10 feet as secured by the low range radio altimeter and by the air/ground sensing system.
(d)
Reverse thrust lever raised.
(2)
The movement of the reverse thrust lever from idle to reverse thrust closes the contacts on a microswitch in the autothrottle switch pack. This and sends power to a latch relay which energizes the sync lock solenoid to release the rotary flex shaft system.
(a) When the sync lock solenoid is energized, a sequence relay and 100ms time delay permits the sync lock to open before hydraulic pressure is applied to the thrust reverser system. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：737-300 400 500 AMM 飞机维护手册 EXHAUST(151)
