(5)  
The normal and alternate hydraulic pressure lines to the brakes are protected by quantity measuring fuses downstream of the antiskid valves. The proper hydraulic source is automatically selected by antiskid shuttle valves downstream of the fuses, in order to use a common brake line running down the strut to the brakes (Ref 32-42-00).

 (6)  
Restrictor-check valves are installed in each brake line to limit the pressure application rate at the brake, but do not restrict flow out of the brake for antiskid release.

 (7)  
Check valves are installed in the return lines of the brake system to prevent return line pressure surges external to the brake system from causing the brakes to drag.

 B.
Metered Brake Pressure Control Functional Description

 (1)  
Controlling pressure at the brakes is accomplished automatically through the autobrake control module or manually using the rudder-brake pedals. During manual operation using the alternate system, the brake metering valves port metered pressure to the brakes. During manual operation using the normal system, the brake metering valves port metered pressure to the brake pressure control valves which port metered pressure to the brakes. A total of four brake metering valves (two per brake metering valve module).

 (2)  
In the automatic mode, a single autobrake pressure control valve is used to apply and maintain brake pressure in the normal system only at the level commanded by the autobrake control unit (Ref 32-42-00).

 (3)  
Brake pressure for stopping wheel spin during gear retract is controlled by gear up pressure to the gear retract braking actuators mounted on the alternate brake metering valves.

 C.
Control (Fig. 5, 6)

 (1)  
Provide electrical power (Ref 24-22-00).

 (2)  
Pressurize main right and left hydraulic systems (Ref 29-11-00).

 32-41-00
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757
MAINTENANCE MANUAL

 (3)  
Check that RESERVE HYD SOURCE and BRAKE PRESS circuit breakers on P11 panel are closed.

 (4)  
For manual control of brakes, apply pressure at pilot's brake pedals (left and/or right), as required.

 (5)  
For automatic control of brakes set autobrake switch position, as required (Ref 32-42-00).

 (6)  
To activate the reserve hydraulic pressure source for brakes, press the RESERVE BRAKE switch on the pilots P1 panel to ON position.

 32-41-00
 ALL  ú ú 03A Page 18 ú Mar 20/94
 
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757 FAULT ISOLATION/MAINT MANUAL
HYDRAULIC BRAKE SYSTEM
COMPONENT SHT 102 FIG. QTY  ACCESS/AREA  REFERENCE 
ACCUMULATOR - (REF 32-44-00, FIG. 101)
 PARKING BRAKE  1  2  METERING VALVE L/R MLG WHEEL WELL ON ALTERNATE  32-41-09 
BRAKE - HYDRAULIC  3  8  MAIN LANDING GEAR 32-41-10 
THERMAL RELIEF CHECK VALVE - (REF 32-44-00, FIG. 101) CABLES - BRAKE CONTROL  1  8  821, FWD CARGO COMPT CLG AREA  32-00-05 
CIRCUIT BREAKERS 3 FLT COMPT, P6,P11
 BRAKE PRESS IND, C1180 1  11S13  * 
PARKING BRAKE VLV, C1179  1  6F4  *
 EICAS, R, M10182 EICAS, L, M10181 ANTISKID AUTOBRAKE, M102 CONTROL UNIT - (REF 32-42-00, FIG. 101) COMPUTER - (REF 31-41-00, FIG. 101) HYDRAULICS RESERVE BRAKE SOURCE, C4292  1  11K22  *
 PNEUMATIC PRESSURE GAGE - (REF 32-44-00, FIG. 101)DISCONNECT - BRAKE  3  8  MAIN LANDING GEAR  32-41-08 
INDICATOR - BRAKE PRESS., N10  3  1  FLT COMPT, P3  *
LIGHT - (REF 32-44-00, FIG. 101) PARK BRAKE, L413 LIGHT - BRAKE SOURCE, L491  3  1  FLT COMPT, P1  *
MODULE - (REF 32-42-00, FIG. 101) NORMAL ANTISKID VALVE, L&R AUTOBRAKE VALVE, M239 ANTISKID SHUTTLE VALVE, L&R ALTERNATE ANTISKID CONTROL VALVE, L&R MODULE - (REF 32-42-00, FIG. 101) MECHANISM, BRAKE PEDAL BUS 1  1  BULKHD L&R MAIN GEAR WHEEL WELLS, FWD 113AL, FWD EQUIP COMPT  32-41-02 32-41-01 
PEDALS - BRAKE (CAPTAIN'S AND FIRST  1  4 FLT COMPT 32-41-00 
RESERVE BRAKE CONTROL, K10426 RELAY - (REF 29-11-00, FIG. 101) PARK BRAKE CLOSE SENSE, K419 RELAY - (REF 32-44-00, FIG. 101) OFFICER'S) 4  FLT COMPT  32-41-00 
BRAKE, LH, S82 BRAKE, RH, S83 SWITCH - (REF 32-42-00, FIG. 101) S415 SWITCH - ALTERNATE SOURCE SELECT VALVE PRESS,  2  1  R MAIN GEAR WHEEL WELL  32-41-04

 * SEE WM EQUIPMENT LIST
Component Index
Figure 101 (Sheet 1)