3. Operation
_________
A. Functional Description
(1)
Antiskid system simplified (Fig. 12)
(a)
Four circuit breakers (ANTISKID 1-5, 2-6, 3-7, 4-8) on P11 provide 28 v dc power to the control unit. Four main wheel cards in the unit compare IRS speed data inputs with wheel speed. This results in a control signal to the antiskid valves which limit hydraulic pressure to the brakes. Two shuttle valve modules shuttle pressure between normal and alternate systems.
(b)
The AUTOBK ANTISKID TEST IND 1 and AUTOBK ANTISKID TEST IND 2 circuit breakers on P11 provide 28 v dc power to the interface/display card for BITE functions. A data bus provides all the tie-ins between wheel cards, autobrake card, BITE card, and the interface/display card. The control unit provides fault signal to the EICAS computers and the ANTISKID light.
(c)
Inputs to control unit affecting antiskid functions include IRS speed data, and landing gear and parking brake lever position signals. The parking brake valve is checked for open to ensure antiskid function.
(2)
Antiskid electrical power and system inputs (Fig. 13)
(a)
Four individual circuit breakers (ANTISKID 1-5, 2-6, 3-7, and 4-8) on panel P11 supply 28 v dc power to four wheel cards in the control unit. The AUTOBK ANTISKID TEST IND 1 and AUTOBK ANTISKID TEST IND 2 circuit breakers on P11 provide 28 v dc power for BITE functions.
32-42-00
ALL ú ú 04 Page 20 ú Sep 28/00
A
757
MAINTENANCE MANUAL
R HYD SYS PWRNORMAL BRK
NORMAL BRKMTR VALVE
MTR VALVE AUTOBRAKE
IRS IRU R MODULE
SWITCHING IRU CTR AUTOBRAKE
AUTOBRAKESHUTTLE
SHUTTLE IRU L
VALVE
VALVE AUTO-BRAKE
PARK
BRAKE
VALVE
CARD
ANTISKID VALVES ANTISKID VALVES 28V DC
AUTOBRKS/ANTISKID
L HYD SYS PWR
TEST IND 2
BRAKERELEASE
28V DC
ANTISKID 1-5
ALTN BRK
ALTN BRKMETER VALVE METER VALVE
BRAKE
28V DC
RELEASE
ANTISKID 4-8
ANTI-
GEAR DOWNSKID
28V DC AND LOCKED ALTN ALTN
CARDS ANTISKID ANTISKID
ANTISKID 2-6
ANTISKID ANTISKIDPROX SW ELEX
(4) SHUTTLE
SHUTTLE VALVE
VALVES VALVESVALVE
UNIT (PSEU)
28V DC
ANTISKID 3-7
FWD WHL SPDXDCR(8 PLACES)
1
234LOCKEDWHEELPROTECTION
5
6 7
8
L IRS SPEED REF
28V DC
INTER-FACE/ BRAKES
HYDROPLANE PROTECTON
LED
(TYP 8 PLACES)TEST IND 1AUTOBRKS/ANTISKID DISPLAYFAULT CARD R IRS SPEED REF
P11 RELAYS DISPLAY
ANTISKID
PARKING BRAKE
VALVE
ANNUNCIATOR PANEL
BITE
CARD
RIGHT &
ANTISKID
SYSTEM PRESS.
ALTERNATE
HYD SYS
METERED PRESS.L/R EICAS CMPTR
ANTISKID/AUTOBRAKE
CONTROL UNIT
RETURN
Antiskid System Simplified
Figure 12
32-42-00
ALL ú ú 03 Page 21 ú Jan 28/02
A
757
MAINTENANCE MANUAL
ANTISKID/AUTOBRAKE CONTROL UNIT
NOTE: ANTISKID CONTROL FOR LEFT GEAR
BRK RELEASE
WHEELS SHOWN, RIGHT SIMILAR COMMAND
Antiskid Control SchematicFigure 13 (Sheet 1)
32-42-00
ALL ú ú 03 Page 22 ú Jan 28/02
A
757
MAINTENANCE MANUAL
NO. 1 ANTISKID VLV
BRK BRK
ON
OFF
MODULE A
FILTERELEMENT
NO. 5 A/SNO. 6 A/S NO. 2 A/S
VLV VLVVLV
RIGHT HYDSYS PRESS
INTERNALS INTERNALS INTERNALS
SAME SAME SAME
AS ASAS
NO. 1 NO. 1 NO. 1
SHUTOFF VLV
ANTISKID ANTISKID ANTISKID
VLV VLV VLV
MTR PRESS
NORM RETURNB
NORM. ANTISKID NO. 1 & 2
VLV MDL HYD FUSE (TYP) ALTN A/S VLVBRK BRK ON
OFF
FLT DISPATCH PLUG E (4 PLS)
NO. 5 & 6ALTN A/S VLV
INTERNALS
SAME
AS
NO. 1 & 2
ANTISKID ALTN LEFT (ALTN)
SHUTTLE VLV MDL F ANTISKID
HYD SYS VLV
PRESS
MTR PRESS
ALTN RETURN
1
2
A
C
2
BRAKES BRAKES2
NO. 1 ANTISKID NO. 2 ANTISKIDXDCR XDCR C ALTN ANTISKID VLV MDL
D 5
6
B
D
2
BRAKES BRAKES2
FWD
NO. 5 ANTISKID NO. 6 ANTISKID
XDCR XDCR
SYSTEM PRESS.
METERED PRESS.2 TO ANTISKID/AUTOBRAKE
CONTROL UNIT (SH 1)
RETURN
Antiskid Control Schematic
Figure 13 (Sheet 2)
32-42-00
ALL ú ú 11 Page 23 ú Jan 28/02
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：757 AMM 飞机维护手册 起落架 CHAPTER 32 - LANDING GEAR 2(166)
