# US 2018/0023939 A1 · Retractable index pins and methods of operating thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0023939 A1 - Document ID: US20180023939A1 - Status: Published application - Kind: A1 - Application number: 15/218,346 - Filed: 2016-07-25 - Published: 2018-01-25 - Earliest claimed: 2016-07-25 - Assignees: The Boeing Company - Applicants: The Boeing Company - Inventors: Jason L. Hicks; Kevin M. Barrick; Branko Sarh; Harinder S. Oberoi - Web page: https://patentgrep.com/patent/US20180023939A1 ## CPC - G01B 5/25: for testing the alignment of axes - B23P 19/10: Aligning parts to be fitted together - F16B 19/02: Bolts or sleeves for positioning of machine parts, e.g. notched taper pins, fitting pins, sleeves, eccentric positioning rings - B23P 2700/01: Aircraft parts - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - B23P: METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS (arrangements for copying or controlling B23Q) - F16B: DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING (couplings for transmitting rotation F16D) ## Abstract Provided are self-retractable centering assemblies and methods of using these assemblies for alignment of parts having determinant assembly alignment holes. An assembly includes a center pin having a threaded portion threadably engaging a drive component. The assembly also includes a puller bushing rotatably coupled to the drive component. The center pin protrudes through the puller bushing and can slide with respect to the puller bushing when the drive component is rotated relative to the center pin. The sliding distance is controlled by a limiter disposed within the cavity of the puller bushing. During operation, a portion of the center pin extends from the puller bushing and is inserted into alignment holes of parts being aligned. The drive component is rotated relative to the center pin resulting in the center pin being pulled out of the alignment holes while the puller bushing is being pressed against the parts. ## Claims ### Claim 1 A self-retractable centering assembly comprising: a center pin comprising a threaded portion; a puller bushing comprising a cavity, the center pin protruding through the cavity of the puller bushing, the center pin being slidable relative the puller bushing along a center axis of the center pin; a drive component rotatably coupled to the puller bushing, the drive component threadably engaging the threaded portion of the center pin such that rotation of the drive component relative to the center pin and around the center axis of the center pin slides the center pin relative to the puller bushing; and a limiter disposed within the cavity of the puller bushing and limiting a sliding distance of the center pin relative to the puller bushing. ### Claim 2 (depends on 1) The self-retractable centering assembly of claim 1, wherein the limiter is a stop nut threadably engaging the threaded portion of the center pin. ### Claim 3 (depends on 1) The self retractable centering assembly of claim 1, wherein the limiter is a collar of the center pin. ### Claim 4 (depends on 1) The self-retractable centering assembly of claim 1, wherein the limiter is a slot key protruding into a slot of the center pin. ### Claim 5 (depends on 4) The self-retractable centering assembly of claim 4, wherein the slot key is a Woodruff key. ### Claim 6 (depends on 1) The self-retractable centering assembly of claim 1, wherein the limiter is a transverse pin protruding through the center pin in a direction perpendicular to the center axis of the center pin and extending away from the center pin. ### Claim 7 (depends on 1) The self-retractable centering assembly of claim 1, wherein the limiter is a combination of a sliding planar surface of the center pin and a protrusion fixed relative the puller bushing, and wherein the sliding planar surface extends parallel to the center axis of the center pin. ### Claim 8 (depends on 1) The self-retractable centering assembly of claim 1, wherein the center pin is not rotatable relative to the puller bushing. ### Claim 9 (depends on 8) The self-retractable centering assembly of claim 8, further comprising a coupling component non-rotatably engaging the puller bushing and the center pin. ### Claim 10 (depends on 9) The self-retractable centering assembly of claim 9, wherein the coupling component non-rotatably engaging the center pin through an end component non-rotatably connected to an end of the center pin opposite to an insertion portion of the center pin. ### Claim 11 (depends on 8) The self-retractable centering assembly of claim 8, wherein the center pin comprises a collar disposed within the cavity such that both the collar and the cavity have non-circular cross-sectional shapes within a plane perpendicular to the center axis of the center pin. ### Claim 12 (depends on 11) The self-retractable centering assembly of claim 11, wherein the cavity has an elliptical cross-sectional shape within the plane perpendicular to the center axis of the center pin. ### Claim 13 (depends on 8) The self-retractable centering assembly of claim 8, further comprising a slot key protruding into a slot of the center pin and into a sliding slot of the puller bushing. ### Claim 14 (depends on 8) The self-retractable centering assembly of claim 8, further comprising a transverse pin protruding through the center pin in a direction perpendicular to the center axis of the center pin and extending away from the center pin and into two slots of the puller bushing. ### Claim 15 (depends on 8) The self-retractable centering assembly of claim 8, further comprising a sliding planar surface of the center pin and a protrusion fixed relative the puller bushing, wherein the sliding planar surface extends parallel to the center axis of the center pin. ### Claim at position 16 16-20. (canceled) ### Claim 21 A method comprising: retracting a center pin of a self-retractable centering assembly from a first determinant assembly alignment hole of a first part and from a second determinant assembly alignment hole of a second part, the first second determinant assembly alignment hole being aligned relative to the first determinant assembly alignment hole by the center pin, retracting the center pin comprising rotating a drive component of the self-retractable centering assembly relative to the center pin. ### Claim 22 (depends on 21) The method of claim 21, wherein the drive component is rotated around a center axis of the center pin. ### Claim 23 (depends on 21) The method of claim 21, wherein rotating the drive component relative to the center pin causes the center pin to advance axially relative to the drive component. ### Claim 24 (depends on 23) The method of claim 23, wherein rotating the drive component relative to the center pin further causes the center pin to advance axially relative to a puller bushing of the self-retractable centering assembly. ### Claim 25 (depends on 21) The method of claim 21, wherein retracting the center pin comprises pressing a puller bushing against the first part while retracting the center pin. ### Claim at position 22 26-34. (canceled)