-
the output member moves axially against spring 'A' into the
 clearance in the friction disc pack

 -as input torque increases, brake friction in the friction disc pack sends too much input torque through the gearbox casing into the aircraft structure. This limits the output torque
 -more increase in input torque causes more axial movement of the output member against spring 'B'
 -as spring 'B' compresses, the brake friction in the friction disc pack makes sure that the input shaft does not turn
 -the indicator extends to show that lock-out torque has occurred.
 The indication of the lock-out torque occurs only:
 -when hydraulic-power-given torque is released through the gearbox casing into the aircraft structure because of too much load downstream.
 The system can be set again by operation in the opposite direction. The indicator stays extended until it is cancelled manually.

 G. Tracks
 (Ref. Fig. 005)
 The circular-arc tracks are machined from steel and move in
 grease-lubricated vertical-load and side-load rollers.
 Attached to the forward face of the front spar are two ribs, one inboard
 and one outboard of the track. Attached to the ribs are the rollers.
 The tracks retract through holes in the front spar into sealed
 containers. The sealed containers make a projection into the fuel tanks.

 At each end of each moved track is a fixed stop. On retraction, the
 forward stops prevent damage to the track containers, slat and leading
 edge structure. The stops on the rear of the track prevent that the slat
 falls from the wing when the transmission system is disconnected.
 Engagement of the stops does not occur during normal operation.

 The tracks are of inverted-U section. Tracks 2, 3 and 5 thru 12 have a
 steel gear rack bolted in the track channel. The gear rack engages with a
 pinion. Bearings between the track ribs support the pinion. The actuator
 output shaft moves the pinion.

 When tracks 1 and 4 are made, they can have spacers installed in the
 inverted-U channel. This is to get the correct tolerance. The number of
 spacers can be between zero and four.

 7. Operation/Control and Indicating________________________________
 (Ref. Fig. 003, 010, 012, 013)
 A. Hydraulic Actuation
 The SFCC1 controls the valve block of the BLUE hydraulic system and the related motor on the PCU. The SFCC2 controls the valve block of the GREEN hydraulic system and the related motor.
 NOTE : The operation of the valve block of the BLUE hydraulic system and
____ the related motor is given. The operation of the valve block of the GREEN hydraulic system and the related motor is the same.
 NOTE : The operation of the valve block is almost the same for the
____ extension and retraction of the slats. The extend and retract solenoid valves control the direction of the movement of the hydraulic motor.

 (1) Slat Extension (Retraction)
 (a)
 When the SFCC1 receives a command to extend (retract) the slats, it energizes the extend (retract) solenoid valve of the PCU valve block.

 (b)
 The energized extend (retract) solenoid valve lets hydraulic fluid flow to one end of the spool of the PCU control valve (referred to as the control valve spool).

 (c)
 The control valve spool moves from the neutral position and lets hydraulic fluid flow to:

 -
the POB solenoid valve

 -
the extend (retract) side of the motor.

 (d) SFCC1 energizes the POB solenoid valve:
 -
the POB releases

 -
the motor moves the differential gearbox in the low-speed mode

 -
the slats extend (retract).

 (e) As the slats get near to the specified position:
 -
the SFCC1 energizes the extend (retract) solenoid valve (all three solenoid valves are now energized)

 -
the two ends of the control valve spool receive fluid pressure

 -equal hydraulic forces occur on the control valve spool
 -the springs move the valve spool in the direction of the neutral position
 -
a restriction of fluid flow to the motor occurs

 -
a reduction of the rate of slat travel occurs.

 (f) When the slats get to the specified position:
 -
the SFCC1 de-energizes all three solenoid valves

 -
the control valve spool moves to the neutral position

 -fluid flow to the motor stops
 -the POB comes on.
 (g) The slats stay locked by the POB until the next movement is specified.
　
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