The wheels include a Tire Pressure Indicating System (optional)
(Ref: 32-49-00).
2. Component Location__________________
Not applicable
3. System Description__________________
(Ref. Fig. 001)
A. Wheels (Ref: 32-41-00)
The wheels are made of two half wheels machined from aluminium alloy forgings and have a radial tubeless tire installed .It is possible to use conventional (bias ply) tires as an option.
1EFF : 401-499, 1 32-40-00Page 1 1 1 Config-2 Aug 01/05 1 1 1CES 1
Brake system - Schematic
Figure 001
1EFF : 401-499, 1 32-40-00Page 2 1 1 Config-2 Aug 01/05 1 1 1CES 1 B. Normal Braking (Ref. 32-42-00)
The Normal braking system is electrohydraulic and includes a computer, which is the Braking / Steering Control Unit (BSCU). The BSCU controls the operation of the electrohydraulic valves in the system to decrease the speed of the aircraft. The hydraulic pressure that operates the brake pistons is supplied from the Green Main Hydraulic Power system (Ref. 29-11-00).
The system has two modes of operation, manual and automatic, and gives automatic anti skid protection in each mode. Each brake unit gets separate pressure control to supply the anti skid protection. The WHEEL page shows when the anti skid function operates. A switch (A/SKID) in the cockpit lets you cancel the system. If the switch is set to OFF, brake operation will go to the Alternate Braking Without Anti Skid system (Ref. 32-44-00).
During manual braking, the input signals to the computer come from the two pairs of brake pedals (through the related transmitter unit) in the flight deck. Thus the quantity of hydraulic pressure that goes to the brake units is in proportion to the travel of each related brake pedal. Each pedal independently controls braking to the related MLG.
Three pushbutton switches in the cockpit set the auto braking to be used during a landing.There are three deceleration modes (LO, MED or MAX).MAX mode is selected before Take-off.
If a brake pedal supplies an input signal which is more than the set auto value it cancels the automatic braking program.
If specified failures occur in the system, control automatically changes to the Alternate Braking system (Ref. 32-43-00) or (Ref. 32-44-00).
C. Alternate Braking with Anti Skid (Ref. 32-43-00)
The Alternate braking system with anti skid is the secondary, electrohydraulic braking system. It automatically becomes available if:
-specified failures occur in the Normal braking system (Ref. 32-42-00)
-the pressure of the Green main hydraulic power supply (Ref. 29-11-00) is less than a specified value.
An analog computer ABCU (Alternate Braking Control Unit) controls the operation of the alternate braking system.
Braking inputs can only be made at the brake pedals and the BSCU provides the anti-skid control (Ref. 32-42-00). The hydraulic pressure that goes
1EFF : 401-499, 1 32-40-00Page 3 1 1 Config-2 Aug 01/05 1 1 1CES 1 to the second set of pistons in the brakes (Ref. 32-42-00) is supplied from the Yellow Main Hydraulic Power supply (Ref. 29-13-00). The quantity of hydraulic pressure that goes to the brake units is in proportion to the travel of each related brake pedal. Each pair of brake units (on the same gear) get separate pressure control to supply the anti skid function.
D. Alternate Braking without Anti Skid (Ref. 32-44-00)
The Alternate braking without anti skid system is the secondary mode of operation of the Alternate braking with anti skid system (Ref. 32-43-00). The system is automatically available when the anti skid function is not available. This occurs when:
-
the A/SKID switch is set to OFF
-
the Yellow Main Hydraulic Power supply is not available.
-
the Anti skid function of the BSCU is faulty.
The system uses the same hydromechanical components as the Alternate braking with anti skid system.If the Yellow Hydraulic Power supply is lost, the accumulator (filled from the Yellow HP) gives sufficient power for at least seven full brake application.
A triple pressure indicator in the cockpit shows the braking accumulator pressure and the pressure at the brakes.
E. Parking/Ultimate Emergency Braking (Ref. 32-45-00)
The parking brake system is an electrohydraulic system. It uses the components of the alternate braking system to send pressure to the brakes. Its primary function is to prevent movement of the aircraft when it is parked. It can also be used to stop the aircraft during towing or in an emergency.
The parking brake system gets its hydraulic power supply from the accumulator of the Alternate braking system (Ref. 32-44-00) or the Yellow Main Hydraulic Power system (Ref. 29-13-00). The accumulators have sufficient capacity to hold the brakes on for a minimum time of twelve hours.
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