Oleo strut

An oleo strut is an air–oil hydraulic shock absorber used on the landing gear of most large aircraft.^[1] It cushions the impacts of landing and while taxiing^[2] and damps out vertical oscillations.

Nosewheel oleo strut on Su-30MKI aircraft

Operation

An oleo strut has an inner metal tube or piston filled with oil, which is attached to the wheel axle, and which moves up and down in an outer(or upper) metal tube filled with air (or nitrogen) and oil, which is attached to the airframe. An orifice between the two tubes allows oil to flow between them. When the aircraft is stationary on the ground, its weight is supported by the compressed air in the upper chamber.^[1] Some oleo struts have a reverse arrangement, with the gas in the lower chamber, with a piston to keep the gas and oil separate. A metering rod may be used to change the size of the orifice as the piston moves, increasing resistance to motion. Nitrogen is often used instead of air, since it is less prone to causing corrosion. O-rings are used to restrict flow of oil to the orifice.^[2]

References

1. ^ ^{a b} Van Sickle, Neil D., Welch, John F, Bjork, Lewis and Bjork, Linda, "Van Sickle's modern airmanship." Page 125. Retrieved March 12, 2011
2. ^ ^{a b} Woodhouse, Mary and Gifford, Scott "How to make your airplane last forever," Tab Books, 1996, Page 75. ISBN-13: 978-0070717046. Retrieved March 12, 2011