Basic Operation of an Oleo-Pneumatic Strut in a Landing Gear:
An Oleo Strut is a Pneumatic air-oil hydraulic shock absorber used on the landing gear of most of the large aircraft. It is undesirable for an airplane to bounce on landing as it could lead to a loss of control, and could lead to structural damage to the landing gear. Hence the air in the Pneumatic Strut acts as shock absorber and the oil acts as a Damper Control.
On ground – The landing gear is in compressed position
In Air – The landing gear is in the extended position
The A320 landing gear system consists of:
- One Nose Landing Gear:
- They retract forward
- Consists of the Nose Wheel Steering system
- Two Main Landing Gears:
- They retract inboard
- They are equipped with carbon brakes ( for efficient braking even at higher temperatures)
- Consists of the Anti-skid and Auto-brake system
There are 2 wheels provided on each landing gear, making it total 6 wheels including all the landing gears.
The doors, which are fitted to the landing gear struts are operated mechanically and close at the end of gear retraction.
Operation of the Landing Gear
When the landing gear lever is selected to Down: The sequence valves make sure to open the landing gear doors first and then extend the landing gear, after the landing gears have been extended, then the doors close again to reduce drag and maintain a streamline flow.
When the landing gear lever is selected to Up: Again, the landing gear doors are opened first, once they are retracted fully, then only the landing gear doors close.
Two computers known as the Landing Gear Control And Interface Units (LGCIUS) control the extension and retraction of the gear and operation of the doors. There are two computers provided for the redundancy.