Framed landing gear
The main feature of the framed landing gear is that it connects the wheel to the wing or fuselage through a bearing frame. The rods and the shock absorbing strut in the bearing frame are hinged to each other. They only bear axial forces (in the direction of their respective axes) without being subjected to bending moments. Therefore, the structure of the landing gear has a simple structure and a small mass, and has been widely used in light low-speed aircraft in the past. However, modern high-speed aircraft are basically not used because of the difficulty in retracting.
Pillar landing gear
The main feature of the strut type landing gear is that the shock absorber and the bearing strut are combined into one, and the wheel is directly fixed on the piston rod of the shock absorber. The connection between the upper end of the shock absorbing strut and the wing depends on the retraction requirements. For the retractable landing gear, the struts can double as a retractable actuator. The torque is transmitted through the torsion arm and can also be transmitted by a spline connection between the piston rod and the inner wall of the cylinder of the shock absorbing strut. This type of landing gear is simple and compact in construction, easy to retract, and low in quality, and is one of the widely used forms on modern aircraft.
The disadvantage of the strut type landing gear is that the piston rod not only bears the axial force but also bears the bending moment, so it is easy to wear and jam, and the sealing performance of the shock absorber is deteriorated, and the large initial pressure cannot be used.