Expert: Paul Soderman - 3/3/2009

Question
Why we are not using pneumatic system instead of hydraulic system as a main system in landing gear? is their any problem in doing this?

Answer
Yuvari
I am no landing gear expert, but I assume hydraulics are used because the fluid is incompressible and therefore able to move against large forces reliably.  The same is true for all heavy duty equipment such as tractors, backhoes, graders, etc.  Pneumatics is fine for light duty systems such as power tools where the compressibility of air is not an issue.  Pneumatic components, such as pistons, would be much larger than the equivalent hydraulic piston.
Paul