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 Alternate-Brake Distribution Dual-Valve R Figure 008
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 Alternate-Brake Distribution Dual-Valve-Schematic
 Figure 009

 1EFF : 001-049, 051-099, 101-149, 151-199, 1 32-43-00Page 15/16 1201-299, 301-399, 1Config-1 Aug 01/05 1 1 1CES  A check valve is installed to rapidly move the fluid from the chamber D to the brake port C: thus the slide valve can be in the fully open position as soon as the pedals are pushed in and the brakes are filled without delay. In balanced state, the pressure supplied is in proportion to the compression of the spring R1 and consequently to the displacement of the control piston. The pressure increases in the control line as a result of the compression of the return springs of the control piston. The delivery pressure (decreased) in relation to the control piston travel and in relation to the control pressure is shown on the graphs. The maximum pressure supplied is 175 bars (2537 psi).

R
 B. Brake System
 (1) Automatic Selector (Alternate Mode) The primary function of the automatic selector is to select the Normal hydraulic system (Green) (Ref. 32-42-00, paragraph 2.D) or the Alternate system (Yellow) for the supply of the brakes. The Alternate system is used if the Green pressure is not available (selector valve de-energized or faulty, or selector valve energized but with the Green hydraulic system not available). The automatic selector includes a primary stage which selects the system. This primary stage includes:
 -
a differential section piston which operates a slide valve, for Normal braking,

 -
a set of valves for Alternate braking.
 Thus the two systems are isolated.
 When you change from Normal to Alternate, in the middle position, the
 piston which the Yellow pressure at D (Yellow pressure plus
 accumulator back-up) operates:

 -cuts off the return line (E to H),

 -then pressurizes the Alternate brake system (D to H).
 The automatic selector also includes a secondary stage. This
 secondary stage is used to cut off the return from the servovalves of
 the Alternate brake system if:

 -
the Yellow system pressure is lost. The brake Yellow-pressure accumulator is used; as the Alternate servovalve return is isolated, this prevents leakage,

 -
the Parking brake is used. As the return is isolated, this causes the inhibition of the Alternate servovalves. The release of the brake during the electrical test of the servovalves is no longer possible.

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 The spring and the Yellow system pressure at G keep the secondary
 stage in the return open position.
 The secondary stage changes to the return closed position:

 -
when the Yellow system pressure is no longer applied at G (loss of the Yellow system): PG less than or equal to 115 bars (1667 psi), or

 -
when a pressure is applied at J (Parking brake applied): PJ more than or equal to 138 bars (1968 psi).

 (2) Dual Shuttle Valve (Ref. Fig. 010) The dual shuttle valve includes two valves, one for each main gear, installed in a single block adjacent to the Alternate-brake distribution dual-valve. Each valve is used to select either the Alternate system (E or D) (spring biased position) or the Parking system (A) to supply the brake system of the corresponding gear (C or B).
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 Dual Shuttle Valve
 Figure 010

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 (3)
 Alternate Brake-System Pressure-Transmitters and Brake Yellow-Pressure Triple-Indicator (Ref. Fig. 011) Two pressure transmitters measure the pressure at the outlet of the dual shuttle valve, i.e. the pressure supplied either by the Alternate-brake distribution dual-valve or by the Parking-brake pressure limiter. The pressure transmitters send the information to an indicator (brake Yellow-pressure triple-indicator) in the cockpit. The indicator also shows the pressure of the brake Yellow-pressure accumulator.

 (4)
 Alternate Brake Servovalves-Safety Valves

 (a)
 Servovalves (Ref. Fig. 012, 013) One servovalve supplies one brake only. The servovalves are installed on a manifold installed in the shroud. The manifold includes:
　
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