# US 2021/0276697 A1 · Landing gear shrink link mechanism > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0276697 A1 - Document ID: US20210276697A1 - Status: Published application - Kind: A1 - Application number: 17/188,198 - Filed: 2021-03-01 - Published: 2021-09-09 - Earliest claimed: 2018-07-30 - Assignees: The Boeing Company - Applicants: The Boeing Company - Inventors: Christopher M. ALLEY; Leanne M. CAMPBELL; Gabriela K. DEFRANCISCI; Gregory J. VERING; Aaron P. KNOCK; Mitchell MELLOR; Justin D. COTTET - Web page: https://patentgrep.com/patent/US20210276697A1 ## CPC - B64C 25/20: mechanical - B64C 25/12: sideways - B64C 25/34: wheeled type, e.g. multi-wheeled bogies - B64C 25/58: Arrangements or adaptations of shock-absorbers or springs (shimmy-dampers B64C25/50) - B64C 25/60: Oleo legs - B64C 2025/008: {Comprising means for modifying their length, e.g. for kneeling, for jumping, or for leveling the aircraft} - B64C: AEROPLANES; HELICOPTERS ## Abstract A shrink mechanism for use with a landing gear of an aircraft. The landing gear includes an outer cylinder rotatably coupled to a frame of an aircraft about a trunnion axis of rotation and a shock strut assembly movably coupled to the outer cylinder so as to reciprocate along a longitudinal axis of the outer cylinder. The shrink mechanism incudes a first shrink link member pivotally coupled to the outer cylinder, a second shrink link member coupling the first shrink link member to the shock strut assembly, a crank member pivotally coupled to the outer cylinder, a drive member coupling the crank member to a walking beam of a landing gear retract mechanism, and a driven member coupling the crank member to the first shrink link member. ## Claims ### Claim 1 A shrink mechanism for use with a landing gear of an aircraft, the landing gear including an outer cylinder rotatably coupled to a frame of an aircraft about a trunnion axis of rotation and a shock strut assembly movably coupled to the outer cylinder so as to reciprocate along a longitudinal axis of the outer cylinder, the shrink mechanism comprising: a first shrink link member pivotally coupled to the outer cylinder; a second shrink link member coupling the first shrink link member to the shock strut assembly; a crank member pivotally coupled to the outer cylinder; a drive member coupling the crank member to a walking beam of a landing gear retract mechanism; and a driven member coupling the crank member to the first shrink link member. ### Claim 2 (depends on 1) The shrink mechanism of claim 1, wherein: the crank member pivots about a first axis of rotation; and the first shrink link member pivots about a second axis of rotation that is spaced, along the longitudinal axis of the outer cylinder, from the first axis of rotation. ### Claim 3 (depends on 2) The shrink mechanism of claim 2, wherein the first axis of rotation and the second axis of rotation are: substantially parallel with one another; or cross one another. ### Claim 4 (depends on 2) The shrink mechanism of claim 2, wherein the drive member and the driven member extend substantially along the longitudinal axis adjacent one another. ### Claim 5 (depends on 1) The shrink mechanism of claim 1, further comprising: a shrink crank member coupled to the first shrink link member so that the shrink crank member and the first shrink link member rotate as a unit; and wherein the driven member is coupled to the shrink crank member so as to drive rotation of the first shrink link member and effect extension and retraction of the shock strut assembly relative to the outer cylinder and along the longitudinal axis. ### Claim 6 (depends on 5) The shrink mechanism of claim 5, wherein the first shrink link member includes a first end rotatably coupled to the outer cylinder and a second end rotatably coupled to the second shrink link member, the shrink crank member being disposed adjacent the first end of the first shrink link member. ### Claim 7 (depends on 5) The shrink mechanism of claim 5, wherein the first shrink link member includes a crank member receiver configured to receive the shrink crank member so that the shrink crank member is rotationally fixed relative to the first shrink link member. ### Claim 8 (depends on 1) The shrink mechanism of claim 1, wherein: the first shrink link member includes a first end rotatably coupled to the outer cylinder and a second end rotatably coupled to the second shrink link member; and the driven member is pivotally coupled to the first shrink link member adjacent the second end so as to drive rotation of the first shrink link member and effect extension or retraction of the shock strut assembly relative to the outer cylinder and along the longitudinal axis. ### Claim 9 (depends on 1) The shrink mechanism of claim 1, wherein the first shrink link member and the second shrink link member are rotatably coupled to each other so as to fold and unfold relative to each other and lock in an over-center position when unfolded. ### Claim 10 A shrink mechanism for use with a landing gear of an aircraft, the landing gear including an outer cylinder rotatably coupled to a frame of an aircraft about a trunnion axis of rotation and a shock strut assembly movably coupled to the outer cylinder so as to reciprocate along a longitudinal axis of the outer cylinder, the shrink mechanism comprising: a first shrink link member pivotally coupled to the outer cylinder; a second shrink link member coupling the first shrink link member to the shock strut assembly; a crank member pivotally coupled to the outer cylinder; a drive member coupling the crank member to a walking beam of a landing gear retract mechanism; a driven member coupling the crank member to the first shrink link member; a sensor actuator arm coupled to the first shrink link member so as to rotate with the first shrink link member; and a sensor coupled to the outer cylinder; wherein the sensor is configured to sense the sensor actuator arm upon extension of the shock strut assembly. ### Claim 11 (depends on 10) The shrink mechanism of claim 10, wherein the sensor actuator arm includes a target and the sensor is a proximity sensor configured to sense the target. ### Claim 12 (depends on 10) The shrink mechanism of claim 10, wherein the outer cylinder includes a shrink link cavity and the first shrink link member and the second shrink link member are disposed within the shrink link cavity and are enclosed by the outer cylinder. ### Claim 13 (depends on 10) The shrink mechanism of claim 10, wherein: the first shrink link member includes a first end rotatably coupled to the outer cylinder and a second end rotatably coupled to the second shrink link member; and the driven member is pivotally coupled to the first shrink link member adjacent the second end so as to drive rotation of the first shrink link member and effect extension or retraction of the shock strut assembly relative to the outer cylinder and along the longitudinal axis. ### Claim 14 (depends on 10) The shrink mechanism of claim 10, wherein the driven member is coupled to the first shrink link member so as to effect, under impetus of the drive member, folding and unfolding of the second shrink link member relative to the first shrink link member. ### Claim 15 (depends on 10) The shrink mechanism of claim 10, wherein one or more of the drive member and the driven member has an adjustable length. ### Claim 16 (depends on 10) The shrink mechanism of claim 10, wherein the outer cylinder includes a first end having the trunnion axis of rotation and a second end longitudinally spaced from the first end, the crank member being pivotally coupled to the outer cylinder between the first end and the second end. ### Claim 17 (depends on 10) The shrink mechanism of claim 10, wherein the outer cylinder includes a first end having the trunnion axis of rotation and a second end longitudinally spaced from the first end, the crank member being pivotally coupled to the outer cylinder at the first end opposite, relative to the trunnion axis of rotation, the second end. ### Claim 18 (depends on 10) The shrink mechanism of claim 10, wherein the outer cylinder includes a shrink link cavity and the first shrink link member and the second shrink link member are disposed within the shrink link cavity. ### Claim 19 A shrink mechanism for use with a landing gear of an aircraft, the landing gear including an outer cylinder rotatably coupled to a frame of an aircraft about a trunnion axis of rotation and a shock strut assembly movably coupled to the outer cylinder so as to reciprocate along a longitudinal axis of the outer cylinder, the shrink mechanism comprising: a first shrink link member pivotally coupled to the outer cylinder; a second shrink link member coupling the first shrink link member to the shock strut assembly; a crank member pivotally coupled to the outer cylinder; a drive member coupling the crank member to a walking beam of a landing gear retract mechanism; and a driven member coupling the crank member to the first shrink link member; wherein the first shrink link member and the second shrink link member are rotatably coupled to each other so as to fold and unfold relative to each other and lock in an over-center position when unfolded. ### Claim 20 (depends on 19) The shrink mechanism of claim 19, wherein the outer cylinder includes an over-center stop surface configured to couple with one or more of the first shrink link member and the second shrink link member to effect over-center locking of the first shrink link member and the second shrink link member.