Oleo struts absorb and dissipate shock loads using a combination of two fluids — a gas and a hydraulic fluid — contained in two chambers — a cylinder and a piston. ... Gas in the upper chamber, functioning like a spring, is compressed by the hydraulic fluid to absorb the impact of touchdown as well as bumps during taxiing.

What absorbs the impact of landing on an oleo strut?

An oleo strut is a type of hydraulic shock absorber that is equipped on most commercial aircraft. A steel coil spring stores the impact energy then releases it into the oleo strut, where it is absorbed.

What is the difference between spring oleo struts and air oleo shock struts?

In spring oleo struts, the spring supports the A/C weight on the ground and during taxiing and oleo strut aborts the shock of landing. In air oleo struts, the air supports the A/C weight on the ground and abserts shocks during taxiing and oleo strut aborts the shock of landing.

Why is both fluid and air used in the design of an air oil oleo strut?

The “oleo” strut uses compressed air or nitrogen combined with hydraulic fluid to absorb and dissipate the shock of landing, and to damp the recoil to minimize bounced landings.

Why is it called oleo strut?

History and applications

Vickers' oleo strut was first applied to an aeroplane by the French aircraft company Breguet Aviation. The design proved to be viable and was extensively adopted across the aviation industry for fixed undercarriages, becoming simply referred to as an "Oleo unit" or undercarriage leg.

How it works Oleo Strut

Is a strut a shock?

The major difference between shocks and struts is that a strut is a structural part of the vehicles suspension system where a shock is not. A strut is also crucial part of the vehicles steering system and greatly affects alignment angles.

How much hydraulic fluid should be put into an oleo strut?

Typically it takes around a gallon of hydraulic fluid to service three struts. Nitrogen is better than compressed air for strut servicing because it is drier and doesn't vary in pressure as much as air; it is also less corrosive to the inside of the strut housing.

What does oleo imply with regards to shock struts?

a shock-absorbing strut in the landing gear of some airplanes, consisting of a telescopic cylinder containing oil.

What kind of undercarriage do small Cessna aircraft like the 172 use?

First flown in 1955, more 172s have been built than any other aircraft. It was developed from the 1948 Cessna 170, using tricycle undercarriage, rather than a tail-dragger configuration. Measured by its longevity and popularity, the Cessna 172 is the most successful aircraft in history.

How does the strut strengthen the landing gear?

Spring Steel Struts

These aircraft use strong, flexible materials like steel, aluminum or composites to help absorb the impact of a landing. As your plane touches down, the springs flex upward, dissipating and transferring the impact load to your airframe at rate that (hopefully) doesn't bend your plane.

What are the 4 types of landing gear?

Landing gear is specially designed to support the load of an aircraft during surface operation and when landing.
...
Air Dollies

• - Wheel Dollies.
• - Landing Gear Dollies.
• - Wheel and Brake Dollies.

What is non absorbing landing gear?

[Figure 13-13] The most common example of this type of non-shock absorbing landing gear are the thousands of single-engine Cessna aircraft that use it. ... Non-shock absorbing struts made from steel, aluminum, or composite material transfer the impact forces of landing to the airframe at a non-damaging rate.

What type of oil is used in an oleo strut?

The main structure of the oleo strut consists of a piston that's attached to the wheel and a cylinder that's attached to the airframe. Inside the tubes are what's generally referred to as oil, but usually is hydraulic fluid, and compressed air or nitrogen.

What is a shimmy damper?

The shimmy damper is a hydraulic fluid-filled cylinder that prevents rapid movement of the nose or main landing gear without interfering with slower operations.

Why do most aircraft tire manufacturers recommend that the tubes in newly installed tires be first inflated?

Why do most aircraft tire manufacturer recommend that the tubes in newly installed tires be first inflated, fully deflated, and then reinflated to the correct pressure? To allow the tube to position itself correctly inside the tire.

What resists the shocks during taxiing in an oleo pneumatic strut?

Gas in the upper chamber, functioning like a spring, is compressed by the hydraulic fluid to absorb the impact of touchdown as well as bumps during taxiing. ... The hydraulic fluid, therefore, restricted by the orifice, acts to dampen the movement of the piston during shock absorption and recoil.

What is meant by oleo strut?

: a cylindrical strut with a built-in telescopic shock absorber that damps or absorbs rectilinear shock (as in an aircraft landing gear) by forcing oil up through an orifice in the bottom of a hollow piston into an air-compression chamber.

What is the oleo?

Oleo is a term for oils. It is commonly used to refer to a variety of things: Colloquial term for margarine, a.k.a. oleomargarine not just vegetable fats but can be tallow. Oleic acid. Oleo strut, a type of shock absorbers on aircraft landing gear.

What two fluids compose a shock strut?

The upper cylinder of a shock strut typically contains a valve fitting assembly. It is located at or near the top of the cylinder. The valve provides a means of filling the strut with hydraulic fluid and inflating it with air or nitrogen as specified by the manufacturer.

What helps control oscillations of the nose gear?

A shimmy damper helps control oscillations of the nose gear. Nose gear struts are often equipped with a locking or disconnect pin to enable quick turning of the aircraft while towing or positioning the aircraft when on the ramp or in a hangar.

How do I service shock my struts?

Release any air pressure in the shock strut. Remove the air service valve assembly. Fill the strut to the level of the service port with approved hydraulic fluid. Attach the bleed hose to the service port and insert the free end of the hose into a container of clean hydraulic fluid.

What are the signs of a bad strut?

• Instability at highway speeds. ...
• Vehicle “tips” to one side in turns. ...
• The front end dives more than expected during hard braking. ...
• Rear-end squat during acceleration. ...
• Tires bouncing excessively. ...
• Unusual tire wear. ...
• Leaking fluid on the exterior of shocks or struts.

Do struts leak fluid?

Generally a strut or shock will start to leak fluid as they age. This is usually due to internal seals failing, which can be a result of our less than perfect roads. ... Most vehicle manufacturers agree that slight oil collecting on the strut or shock absorber is considered normal and to be expected with age.

How long does a strut last?

So how long do shocks and struts last? On average shocks and struts can last 5-10 years or 50,000-100,000 miles under ideal driving conditions. Many factors can affect the lifespan of these components to include: manufacturer, bad roads, heavy loads, towing, hard braking and aggressive driving.