The lengths of the links comply with the conditions: A͞B=D͞C and A͞D=B͞C. Thus, figure ABCD is a parallel-crank linkage whose connecting rod BC mounts landing wheel a. Piston rod 5 of retracting cylinder 3 is connected by turning pairs B to links 1 and 4. Cylinder 3 and link 1 turn about fixed axes D and A of the aircraft frame. When piston rod 5 moves out of cylinder 3, links 1 and 2 are turned counterclockwise, and the landing gear is retracted as shown by the dash lines.
$1422$LG,AL$