Page 43 D633W101-BEJ May 05/2003
TRAS -FUNCTIONAL DESCRIPTION -CONTROL
The directional control valve (DCV) switch moves to the retract position and de-energizes the directional control solenoid valve. The DCV moves to the retract position. This permits hydraulic power to retract the hydraulic actuators.
The sync lock switch moves to the retract position and de-energizes the sync lock relay. A 10 second time delay keeps the sync lock relay energized to make sure retraction is complete. When sync lock relay de-energizes, the sync lock solenoid valve closes. This locks the sync lock/manual drive unit.
Training Information Point
You use the thrust reverser test enable switch to extend the thrust reverser sleeves to do maintenance. When you push and hold the switch, the EEC permits the isolation solenoid valve to energize when the engine is not running.
EFFECTIVITY BEJ ALL 78-34-00
Page 44
D633W101-BEJ May 05/2003
PW4000 SERIES ENGINES
777 AIRCRAFT MAINTENANCE MANUAL
TRAS -FUNCTIONAL DESCRIPTION -CONTROL
EFFECTIVITY BEJ ALL 78-34-00
Page 45
D633W101-BEJ May 05/2003
TRAS -FUNCTIONAL DESCRIPTION -ACTUATION
General
To extend or retract the thrust reverser (T/R) sleeves, hydraulic pressure must release the sync locks and move the hydraulic actuators.
To release the sync locks, hydraulic pressure goes through the sync lock valve (SLV) to the sync locks.
To move the thrust reverser (T/R) sleeves, hydraulic pressure goes to the actuators in this sequence:
*
Isolation valve (IV)
*
Directional control valve (DCV)
*
Hydraulic actuators.
Flow tees hydraulically connect the components of the two thrust reverser halves to the control components in the strut. The flow tees in the lines from the directional control valve (DCV) also contain orifices to hydraulically synchronize the thrust reverser halves.
Extend
This sequence occurs when there is a command to extend the thrust reverser sleeves:
* The sync lock switch in the thrust lever sends a signal through a relay in the electrical load management system (ELMS) to energize the sync lock solenoid valve. The sync lock solenoid valve opens and supplies hydraulic control pressure through the sync lock valve to the sync lock/manual drive units. The hydraulic control pressure moves the lock mechanisms in the sync locks to release the sync shafts.
*
The directional control valve (DCV) switch in the thrust lever microswitch pack sends a signal to energize the directional control solenoid valve. The directional control solenoid valve opens and supplies hydraulic control pressure to the DCV. This moves an internal spool valve to the extend position.
*
The electronic engine control (EEC) energizes the isolation solenoid valve. This supplies internal hydraulic pressure to move the isolation shutoff valve to the open position. The open shutoff valve supplies hydraulic system pressure to the TRAS pressure port of the isolation valve to the directional control valve.
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本文链接地址：777 AMM 飞机维护手册 发动机排气 Engine Exhaust PW 777 AIRCRAFT MAINTENANCE MANUAL(43)
