-when the valve spool reaches the "pressure on point", the SFCC energizes the POB solenoid valve to release the POB
-the hydraulic motor receives fluid flow and starts to turn the transmission
-with the valve spool fully moved, the motor gets the maximum available fluid flow and turns at full speed.
(c) Normal Shutdown Sequence
R (Ref. Fig. 014)
During the normal shutdown sequence:
-electrical power is removed from the drive-direction solenoid when the flaps are 6.69 deg. (FPPU) away from the set position.
-the opposite direction solenoid is energized at this time.
-full hydraulic system pressure moves the spool towards the center position. Restrictors control the speed of this movement of the spool.
-
the drive-direction solenoid is now energized again when the spool gets to the "Low Speed" operation position. Spring pressure now moves the spool, at a slower speed, towards the center position. A restriction of hydraulic fluid into the pressure-line upstream of the solenoid valve now controls the speed of movement of the spool.
-
the motor now operates at "Low Speed" because of the decreased size of the pressure and pressure-return connections.
-electrical power is removed from the drive-direction solenoid and the POB solenoid valve when the flaps are 0.177 deg. (FPPU) away from the set position.
-when the LVDT indicates that the valve spool is 1.5 mm from the center position the SFCC removes power from the opposite direction solenoid valve.
-the valve spool moves to the center position and stops.
(d) Pressure Maintaining Function
Emergency or stand-by hydraulic power has a limited flow capacity. At a time of operation with emergency or stand-by hydraulic power, it is necessary to prevent a sudden decrease in supply pressure. A sudden decrease in supply pressure can occur because of too much demand by the flap system. This could cause an application of the POB at any time.
The force and the rate of the spring, together with the port area/valve movement property, give the function that maintains the pressure of the valve.
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R PCU Operation - Normal Shutdown Sequence Figure 014
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As the supply pressure decreases, the valve closes slowly. This reduces the flow rate to the motor and thus the work-load on the pump. This prevents the work-load of the slat/flap system to cause a sudden decrease of the supply pressure.
(e) Single System Operation
The loss of the hydraulic pressure to one of the two motors causes the POB to apply and hold the motor output shaft. This locks one half of the differential gearbox. The serviceable motor then gives sufficient output torque at half speed, at the gearbox output shaft.
B. Right Angle Gearbox 6203CM(6253CM)
R (Ref. Fig. 015)
A right-angle gearbox is installed in each wing. Their gear ratio is 1:1. Bolts attach each right-angle gearbox to the structure. The input and output shafts have splined ends for connection to the torque shafts of the transmission system. The input and output shafts have reversed lip seals which make sure that unwanted material does not get into the gearbox. The gearbox is filled with grease. There are inspection plugs through which you can examine the lubricant.
C. Line Gearbox 6209CM(6259CM)
R (Ref. Fig. 016)
The line gearbox has a ratio of 1:1. Bearings, seals and the procedures for lubrication and inspection are almost the same as those used on the right angle gearbox.
D. Bevel Gearbox 6217CM(6267CM)
R (Ref. Fig. 017)
The bevel gearbox has a ratio of 1:1. Bearings, seals and the procedures for lubrication and inspection are almost the same as those used on the right angle gearbox.
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R Right Angle Gearbox Figure 015
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R Line Gearbox Figure 016
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R Bevel Gearbox Figure 017
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E. Torque Shafts and Steady Bearings
**ON A/C 001-049, 051-061, 101-103, 201-203,
(Ref. Fig. 018)
R **ON A/C 062-099, 104-149, 151-199, 204-299, 301-399, 401-499,
(Ref. Fig. 018A)
**ON A/C ALL
(Ref. Fig. 019)
Each torque shaft is a splined/bolted assembly which has, as applicable:
-universal joints
-flexible joints
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