AGK Systems - Wheels Tyres And Brakes

Question 1

Tyre construction.

Answer 1

Flexible casing of: rubber coated rayon, cotton or nylon ply cords.
Wrapped around beads at each edge of tyre.
Beads made from steel wires.
Casing plies comprise the tyre carcass.
Rubber tread moulded to the carcass.
Normally inflated with nitrogen.

Question 2

What is a ply rating?

Answer 2

Indication of tyre strength.

Question 3

What is tread?

Answer 3

Made from rubber, helps expel water and provide grip.

Question 4

What is tubeless?

Answer 4

No inner tube to contain gas.

Question 5

What is bias (cross-ply)?

Answer 5

Piles are laid in pairs at 90 degrees to each other.

Question 6

What is radial?

Answer 6

Piles are laid from bead to bead - perpendicular to the centreline of the tyre

Question 7

What is retread?

Answer 7

New tread heat bonded onto old carcass.

Question 8

What are tube tyres?

Answer 8

Inner tube with inflation valve attached to it, fed through a hole in the wheel.

Question 9

What is tyre creep?

Answer 9

Sudden accelerations cause tyre to slip around the wheel.
Creep is greatest with a new tyre.
Monitored with creep marks:
1inch wide for tyres less than 24inch in diameter,
1.5inch wide for over 24inch in diameter.

Question 10

Ribbed tyre vs blocked tyre tread.

Answer 10

Ribbed - even tread wear. Resistant to sidewall damage. Goof for water in one direction.
Blocked - Able to grip to mud etc.

Question 11

What is tyre speed rating?

Answer 11

Speed rating must match or exceed maximum anticipated rolling speed of aircraft.

Question 12

Tyre wear limits.

Answer 12

Ribbed - minimum tread 2mm, measured from bottom groove.
Tyre is on limit when marker bar is at same height as rib.

Blocked - block pattern is still visible

Question 13

Tyre inspection.

Answer 13

Cuts, bulges, FOD, contamination, creep, wear, pressure.

Question 14

What is aquaplaning?

Answer 14

Wedge of water builds at front of tyre, as speed increases tyre lifted off surface.

Question 15

Aquaplaning formula.

Answer 15

Aquaplaning speed = 9 sqr rt (P) [P=psi]
or 34 sqr rt (P) [Kg/cm^2)

Question 16

Tyre overheat protection.

Answer 16

Each wheel is equiped with a fusible plug which is deisgned to burst before the tyre fails.

Question 17

Wheel brakes.

Answer 17

LArge aircraft use multiple discs, uses hydraulic power mostly.

Question 18

How do you measure brake wear?

Answer 18

Special gauge used to measure gap between disc and brake housing when brakes applied.

Question 19

Large aircraft brake systems.

Answer 19

Series of pads arranged around sides of stator assembly, in between each pair of stators is a rotor segment. A torque plate carries the operating pistons. Discs segmented and held together relatively loosely. Rotors made from steel alloy. Brakes pads usually made from ceramic material.

Question 20

Brake wear indicator pin.

Answer 20

The pin should protrude through the housing.
If it is flush against the housing, brakes are unserviceable.

Question 21

How the parking break work?

Answer 21

Locks the pressure in.
Need brakes applied already.

Question 22

Electric brakes.

Answer 22

Each assembly has 4 actuators and motors.
Motor torque proportionally applies pressure via the actuator to squeeze the assembly. Temperature sensors alter brake pressure to allow for thermal expansion/contraction.

Question 23

Auto brakes.

Answer 23

Solenoid valve is energised after the wheels spin up. Must be above 70kts to activate.

Question 24

What happens when anti skid is inop?

Answer 24

dry runway distance can double

Question 25

Electronic anti-skid system.

Answer 25

Uses a single phase AC generator driven by the wheel assembly. Controllers controls anti skid.