Plane wheels and tyres are a very critical and sensitive part of a plane. in combination with the strut they combine together to form a planes oleo-pneumatic strut.
plane wheels are classified in two:-
- loose/detachable flange type
- divided wheels
Fusible plugs are placed in some wheels with tubeless tires to avoid tire blowout. Most aircraft use tubeless tires filled with nitrogen.
types of plane tyres
- bias or cross ply
- radial ply
The tyres consist of a casing made of rubber which is reinforced with plys of cotton, rayon or nylon cords which are then coated with rubber on the wheels.
plys are are written on the tire together with tire strength . Beads are the end of the tire that enter the rim and are made of high tensile wire strands coated with rubber on the wheels.
Depending on the pressure plane tyres stress on the plane wheels a runway path is decided i.e-
- low pressure tyres – 25-35 p.s.i 1.73 to 2.42 bar used on grass run-ways
- medium pressure tyres – 30-70 p.s.i or 2.42 to 4.83 bar used on dirt runways
- high pressure tyres – 70- 90 p.s.i or 4.83 to 6.21 bar used on concrete runway
- Extra high pressure tyres – over 90 p.s.i with some tyres of these type being inflated to 350 p.s.i or 24.2 bar also used in concrete runway
Aqua planning – these is when a plane lands on or takes off in water.
plane tyres can be retreaded instead of buying new ones. the use of reverse pitch, reverse thrust and ground spoilers help reduce braking requirements.
On aircraft with undercarriage bogies . The torque developed during braking is transferred to the undercarriage leg by brake torque rods in multi-plate brake units
Aircraft brakes are normally hydraulically operated. Their either :-
- carbon brakes
- steel brakes
Operating power is normally provided by a hydraulic system but pneumatic and electrical systems are also used. It has another way of being activated in case of failure that is wheel wells are closed when the gear is up.
Trunion – The leg is attached to the wing spars by a cylindrical trunion on which the leg is free to rotate laterally.
There are upper and lower torque links, drag strut,down lock actuator. spring strut outer cylinder and jury strut.
oleo pneumatic strut – used in planes and forms the upper part . The lower part is made of wheel boogie and truck beam.
E.G.P.W.S – Enhanced ground proximity warning system. it is used to give a too low gear warning.