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. Links 1 and 3 turn about fixed axis D of the aircraft frame member. Oil shock absorber 2 is mounted between points E and C. Hence, the whole system EDC turns about common axis D. Retracting cylinder 5 turns about fixed axis F of the aircraft frame and its piston rod 6 is connected by turning pair E to system EDC. When piston rod 6 moves into retracting cylinder 5, links 1, 3 and 4 are turned counterclockwise, and the landing gear is retracted as shown by the dash lines.
$1421$LG,AL$