DOC AIRBUS | AMM A320FWHEELS AND BRAKES - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
A. Tires, Wheels, Brakes
The main gear wheels have multidisc carbon brakes that two sets of independently supplied pistons operate; the Green hydraulic system supplies one set, the Yellow hydraulic system supplies the other set with the aid of one brake Yellow pressure accumulator.
Each brake has automatic adjusters, two wear pin indicators and a temperature sensor.
The main gear wheels include fusible plugs which protect the wheel and the tire against burst if an overheat occurs.
The wheels have radial tires.
A Tire Pressure Indicating System (TPIS) monitors the tires pressures (Optional).
The main gear wheels have multidisc carbon brakes that two sets of independently supplied pistons operate; the Green hydraulic system supplies one set, the Yellow hydraulic system supplies the other set with the aid of one brake Yellow pressure accumulator.
Each brake has automatic adjusters, two wear pin indicators and a temperature sensor.
The main gear wheels include fusible plugs which protect the wheel and the tire against burst if an overheat occurs.
The wheels have radial tires.
A Tire Pressure Indicating System (TPIS) monitors the tires pressures (Optional).
2. System Description
A. Anti Skid System
The anti skid system gives the maximum braking efficiency as it keeps the wheels at the limit of skidding.
The brake release orders generated are sent to the four Normal or four Alternate brake servovalves and to the ECAM system. This system gives a display of the released brakes and of the actions and limitations associated with the various possible failures.
The A/SKID & NOSE WHEEL switch on the center instrument panel is used to disconnect the anti skid system and the nose wheel steering.
The anti skid system gives the maximum braking efficiency as it keeps the wheels at the limit of skidding.
The brake release orders generated are sent to the four Normal or four Alternate brake servovalves and to the ECAM system. This system gives a display of the released brakes and of the actions and limitations associated with the various possible failures.
The A/SKID & NOSE WHEEL switch on the center instrument panel is used to disconnect the anti skid system and the nose wheel steering.
B. Braking Modes
The four braking modes available depend on:
The four braking modes available depend on:
Brake System - Schematic- the hydraulic system used,
- the position of the A/SKID & NOSE WHEEL switch and PARK BRK control switch.
(1) Normal Braking
You get normal braking when:
The regulation is performed on the four Normal brake servovalves.
You get normal braking when:
- the Green hydraulic high pressure is available,
- the A/SKID & NOSE WHEEL switch is in the ON position,
- the PARK BRK control switch is in the OFF position or the PARK BRK control is in the ON position and the parking brake pressure really applied is less than 35 bar (507 psi).
- through the pedals,
- automatically: on the ground by the autobrake system or in flight when the landing gear control-lever is placed in the UP position during 3 seconds.
The regulation is performed on the four Normal brake servovalves.
(2) Alternate Braking with Anti Skid
The Alternate braking with anti skid associates the Yellow high pressure with the anti skid regulation. You get this mode automatically:
A hydraulic selector causes changes between the Green and Yellow systems automatically.
The orders are entered through the pedals only and an auxiliary low-pressure hydraulic-system transmits them. The pressure supplied to the left and right brakes is shown on a brake Yellow-pressure triple-indicator installed on the center instrument panel.
The anti skid system and related indicating are operative.
The regulation is performed on the four Alternate brake servovalves.
The Alternate braking with anti skid associates the Yellow high pressure with the anti skid regulation. You get this mode automatically:
- if the Green pressure is not available or falls during braking,
- if certain failures occur on the Normal system: brake pressure not sufficient after gear extension or anti-skid system failure in flight before landing with gear downlocked.
A hydraulic selector causes changes between the Green and Yellow systems automatically.
The orders are entered through the pedals only and an auxiliary low-pressure hydraulic-system transmits them. The pressure supplied to the left and right brakes is shown on a brake Yellow-pressure triple-indicator installed on the center instrument panel.
The anti skid system and related indicating are operative.
The regulation is performed on the four Alternate brake servovalves.
(3) Alternate Braking without Anti Skid
The Alternate braking without anti skid differs from the above mode in that the anti skid regulation is no longer available.
It can be:
The brake Yellow-pressure triple-indicator shows the pressure of the accumulator. The operation of the pushbutton which controls the Yellow electric pump fills the power accumulator.
The accumulator can supply at least seven full brake applications.
The Alternate braking without anti skid differs from the above mode in that the anti skid regulation is no longer available.
It can be:
- disconnected electrically (A/SKID & NOSE WHEEL switch in the OFF position or power supply failure),
- disconnected hydraulically if only the brake Yellow-pressure accumulator supplies the brakes (then the A/SKID & NOSE WHEEL switch can be in any position).
The brake Yellow-pressure triple-indicator shows the pressure of the accumulator. The operation of the pushbutton which controls the Yellow electric pump fills the power accumulator.
The accumulator can supply at least seven full brake applications.
(4) Parking Brake
When the PARK BRK control switch is set to ON (applied):
The return lines are shut off to permit to hold the brakes on for a minimum of twelve hours. The red warning light flashes. The CONFIG PARKING BRAKE ON message appears on the upper ECAM DU when:
When the PARK BRK control switch is set to ON (applied):
- the other braking modes are disconnected,
- the brakes are supplied with Yellow high pressure or accumulator pressure.
The return lines are shut off to permit to hold the brakes on for a minimum of twelve hours. The red warning light flashes. The CONFIG PARKING BRAKE ON message appears on the upper ECAM DU when:
- the parking-brake control switch is in the ON (applied) position,
- one engine is at full throttle.
C. Auto Brake
This system:
The ground spoiler extension command starts the braking action. The Green DECEL legend on the upper half of the pushbutton switch comes on:
This system:
- decreases the number of flight crew actions if an acceleration-stop (MAX mode) occurs,
- or keeps the deceleration to a pre-set limit (LOW or MED) when landing.
The ground spoiler extension command starts the braking action. The Green DECEL legend on the upper half of the pushbutton switch comes on:
- when you get the set deceleration rate, i.e.: 2 m/s 2 in LOW mode or 3 m/s 2 in MED mode,
- or when you get a 0.27 g deceleration in the MAX mode.
- if one (or more) of the arming conditions is (or are) lost,
- if you apply sufficient pressure to the pedals with the aircraft on the ground (takeover through brake pedals).
D. Brake Temperature System
The brake temperature system:
The brake temperature system:
- measures the temperature at each of the four brakes,
- shows the temperature values on the lower ECAM DU,
- tells the flight crew to delay take off or extend the gear (messages on the upper ECAM DU).
E. Ground Tests and BITE
The BITE function of the braking/steering control unit (BSCU) permanently monitors the electrical control and regulation functions.
The faults found are memorized and shown on the CFDIU.
The BITE function of the braking/steering control unit (BSCU) permanently monitors the electrical control and regulation functions.
The faults found are memorized and shown on the CFDIU.
F. Brake Cooling Fans (Optional)
The brake cooling fans permit high speed cooling of the brakes. They thus decrease the turnaround time of the aircraft if you make short flights with high energy braking. One fan is installed on each wheel of the main gear.
A BRK FAN pushbutton switch is used to operate the fans. When the brakes are hot, the HOT legend of the pushbutton switch comes on.
The brake cooling fans permit high speed cooling of the brakes. They thus decrease the turnaround time of the aircraft if you make short flights with high energy braking. One fan is installed on each wheel of the main gear.
A BRK FAN pushbutton switch is used to operate the fans. When the brakes are hot, the HOT legend of the pushbutton switch comes on.
G. Tire-Pressure Indicating System (TPIS) (Optional)
The TPIS shows the pressure of the tires of the main gear and nose gear on the lower ECAM DU.
The TPIS shows the pressure of the tires of the main gear and nose gear on the lower ECAM DU.