The lengths of the links comply with the conditions: A͞E=D͞F and E͞H= A͞D, i.e. figure AEFD is a parallel-crank linkage. Links 4 and 3 turn about fixed axes A and D of the aircraft frame member. Link 1 with wheel a is connected by turning pairs B and E to links 2 and 4. Link 2 is connected by turning pair C to link 3. Piston rod 5 of retracting cylinder 6 is connected by turning pair G to link 3. Cylinder 6 turns about fixed axis H of the aircraft frame. When piston rod 5 moves out of retracting cylinder 6, link 1 is turned counterclockwise and link 3 clockwise, and the landing gear is retracted as shown by the dash lines. When the landing gear is lowered, links 1 and 4, and 2 and 3 are fixed in their extreme (dead centre) positions, forming a truss.
$1439$LG,AL$