What is the primary function of the oleo strut in airplane landing gear?

• A. To provide steering for the nose gear.
• B. To support vertical loads and absorb touchdown impacts by compressing hydraulic oil and gas.
• C. To house the wheel during retraction.
• D. To measure airspeed for gear deployment.

Answer: (B)

The main idea is that the oleo strut acts as a hydraulic shock absorber and spring for the landing gear. It carries the aircraft’s vertical load and absorbs the energy of touchdown by allowing the strut to compress. As the wheel touches down, the piston moves into the cylinder, forcing hydraulic oil through restricted paths to dampen the motion, while the trapped gas (usually nitrogen) compresses to provide the spring force. This combination smooths the touchdown, reduces peak loads on the airframe, and helps control bounce after contact.

It isn’t used to steer the nose gear, so steering mechanisms or linkages handle that function. It doesn’t serve to house the wheel during retraction—the wheel and axle are managed by the gear structure and bay mechanisms. And it isn’t a sensor for airspeed or gear deployment—the speed sensing and gear logic come from dedicated systems separate from the oleo’s energy-absorption role.