US 6032993

I'll run searches against USPTO-style sources and litigation dockets for this specific number.

Let me check litigation/assignment specifically.

US 6,032,993 — Verified Bibliographic Summary

Caveat on the litigation portion of your request: I searched for a CAFC 2026 docket entry (and any district-court/Federal Circuit litigation) tied to 6,032,993. I found no litigation, IPR, or CAFC docket record for this patent. I am not able to query PACER/CourtListener docket databases directly, so treat this as "nothing found in open web sources" rather than a certified negative. Given the maintenance-fee lapse in 2008 (below), the absence is not surprising.

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Bibliographic data

Status: Expired – Fee Related. Fee payment 2003-09-08 (4th year); maintenance-fee reminder 2007-09-17; lapsed for failure to pay maintenance fees effective 2008-03-07 (37 CFR 1.362). The "anticipated expiration 2018-07-01" entry on Google Patents is the statutory end of the 20-year term, not the actual end of enforceability — the patent actually died in 2008.

Related application (as recited in the patent itself): U.S. Ser. No. 09/072,823, filed May 5, 1998, titled "QUICK CHANGE SIDE PULL HOIST RING ASSEMBLY," named Yong Chin Kwon, and stated to be "assigned to the inventor of this application, Soon Chil Kwon." Note the different given name (Yong Chin vs. Soon Chil). The Google Patents "Similar Documents" list shows US 6,039,500 A, "Quick change side full hoist ring assembly," issued 2000-03-21, which appears to correspond to that sibling application — I flag this as a probable but not verified correspondence.

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Abstract (as issued)

"A hoist ring assembly for transporting loads, including an anchor bushing that is threaded into the load and forms the pivot for a releasable swivel hanger assembly with a shackle connectable to an overhead hoist. The swivel hanger is easily attachable to and detachable from the anchor bushing to expedite load movement. The hanger swivels on the anchor bushing in a side-pull or center pull action and has diametral retractable locking pins that enter the anchor bushing in the attached mode that when retracted permit the hanger to be rapidly removed from the anchor bushing."

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Core mechanical concept (from the specification)

The assembly has three sub-assemblies:

1. Anchor bushing assembly 14 — a threaded stud 20 passing through an upper bushing 21 and lower bushing 22, a washer 23, and into a threaded bore in the load. The bushings sit in a bushing sleeve 28 (upper bushing flange in counterbore 27; lower bushing flange 29 under the sleeve). The bushings are axially sized to abut one another and absorb the clamping torque, so the sleeve 28 is free to rotate — that's the swivel joint, and it stays bolted to the load permanently.
2. Hanger ring assembly 16 (or 130) — a body with a large central through-bore 32 that slides axially over the sleeve 28. It carries two opposed, hand-retractable locking pins 37, 38 that pass through bores 34/35 in the body and into diametral bores 39/40 in the sleeve. Pin retention uses a reduced land 42 + axial slot 43 cooperating with thumb screws 45 (tips 46) as the radial blocking member and lower set screws 50 as the travel-limiting member riding in the slot. "Open" legend 52 and "close" legend 48 on the knurled pin heads 40 index the two rotational positions.
3. Shackle assembly 18 — a U-shaped shackle 60 with end bosses 61/62, bore 63, Clevis pins 65 with cross-holes 66 into body bores 68/69, retained by roll pins 70 in cross-bores 71.

Two embodiments: center pull (FIGS. 1–7) where the shackle is generally perpendicular to the hanger body, and side pull (FIGS. 8–15) where the hanger body 130 is elongated and the shackle is generally coplanar with the body. Only the hanger body differs materially between the two.

The advertised commercial benefit: because the hanger/shackle detaches while the anchor bushing stays installed, a two-worker method becomes feasible — one worker installs bushings on many loads while a second worker shuttles the same few hanger/shackle assemblies between loads with the hoist (see "Summary of the Present Invention"). I note this as an asserted advantage from the specification, not an independently verified fact.

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Independent claims — plain-language overview

Claims 1, 2, 3, 5, 6, 7, 9, 10, 11, 12, and 13 are all independent (each opens "A hoist ring assembly, comprising:"). Only 4 and 8 are dependent. This is an unusually large number of independent claims with heavily overlapping scope — a hallmark of a claim set drafted to create multiple narrow fallback positions.

Dependent claims:

• Claim 4 (depends on 3): the pin has an axial slot connecting with an annular groove; a radial member in the hanger ring sits in the groove to block withdrawal in the locked position and moves into the slot to permit withdrawal; the slot also limits outward pin travel (keeps the pin captive). This is the core pin-retention geometry.
• Claim 8 (depends on 7): the anchor bushing includes a rotatable outer sleeve for swiveling.

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Prior art cited on the face of the patent (7 references, all US)

US 4,592,686 (Andrews, 1986); US 4,570,987 (Wong, 1986); US 4,705,422 (CBC Industries, 1987); US 5,248,176 (Fredriksson, 1993); US 5,352,056 (Crosby Group, 1994); US 5,634,734 (Jergens, 1997); US 5,823,588 (Morghen, 1998). The specification's narrative discussion additionally addresses Mueller US 3,492,033, Brawand US 3,163,901, Blatt US 3,628,820, Bateman US 1,321,356, and Jergens part numbers 47311–47319, and notes the Jergens swivel members "cannot be removed from the load without removing the anchor bushing itself" — the gap this patent targets.

Textual anomalies I am flagging rather than silently correcting (per your literal-interpretation rule): the specification cites the Wong patent as "U.S. Pat. No. 4,570,987, issued Feb. 18, 1996" where the front page and reality show 1986; it renders the first-named inventor of US 3,297,293 inconsistently as "Andrewe" in the background section and "Andrew" on the front page; and it recites the U.S. Ser. No. 09/072,823 application as naming "Yong Chin Kwon" while the related granted patent appears to be attributed to Soon Chil Kwon's family.

Forward citations of note (for landscape purposes): US 6,443,514 and US 6,652,012 (both Jergens), US 8,201,867 and US 8,596,701 / US 2012/0306226 (MJT Holdings), and US 8,807,617 (RUD Ketten) — indicating the releasable-hoist-ring art continued to cite this document.

Bottom line: US 6,032,993 is a sole-inventor, unassigned, now-lapsed patent (dead since March 2008) covering a hoist ring whose hanger and shackle can be pulled off a permanently installed anchor bushing by hand, without tools, via retractable locking pins — with 11 largely duplicative independent claims and no found litigation history.

I'll research litigation involving US patent 6032993 across the requested sources.

Litigation Search Results — U.S. Patent No. 6,032,993

Bottom line: I found no evidence of any litigation involving U.S. Patent No. 6,032,993 ("Easily disconnectable hoist ring assembly," Soon Chil Kwon, issued March 7, 2000). No district court cases, no CAFC appeals, no PTAB proceedings, and no ITC Section 337 investigations naming this patent were located.

Case-by-case table

Sources searched and what they returned

Search hits returned the patent itself — e.g., the FPO record (https://www.freepatentsonline.com/6032993.html) and the Google Patents record — plus citations to the '993 patent in later patents (e.g., Justia pages for US 11,376,513 and US 10,213,699 list "6032993 – March 7, 2000 – Kwon"). None of these are litigation records. I must note that a search result that would have surfaced a suit against the '993 patent number did not appear.

Corroborating reasons the negative finding is plausible

1. Ownership. The Google Patents record lists both the original assignee and the current assignee as "Individual" — i.e., inventor Soon Chil Kwon, with no recorded corporate assignment. Individual-owned patents in this mechanical/hoist-ring field are rarely asserted in litigation.
2. Terminal status. The patent is marked "Expired – Fee Related." Legal Events show: maintenance-fee reminder mailed 2007-09-17 (REMI); lapse for failure to pay maintenance fees 2008-03-07 (LAPS); patent expiring 2008-04-29, effective 2008-03-07. The '993 patent therefore had a commercial assertion window of roughly 2000–2008, and it lapsed before the modern NPE-era litigation wave.
3. Prosecution-only history. The full Google Patents record contains no reissue, reexamination, or disclaimer events — only the routine 4-year fee payment (2003-09-08) followed by lapse.

Important distinctions (not litigation, but commonly confused)

• U.S. Patent No. 6,032,993 is not U.S. Patent No. 6,033,500. The related application referenced in the '993 specification — "QUICK CHANGE SIDE PULL HOIST RING ASSEMBLY," Yong Chin Kwon, Ser. No. 09/072,823, filed May 5, 1998 — issued as a separate patent (listed in Google Patents "Similar Documents" as US6039500A, "Quick change side full hoist ring assembly"). If you are looking for assertion activity in this family, the '500 patent should be checked independently; I did not find litigation on it either, but I did not exhaustively search that number.
• The prior-art and subsequent patents shown in the "Cited By" list (e.g., Jergens US6443514B1/US6652012B1, MJT Holdings, Rud Ketten, Sandia's US11192760B1, and the CBC Industries v. The Crosby Group Markman ruling on U.S. Pat. No. 5,848,815) are unrelated patents in the same field — they are not litigation involving the '993 patent, and I did not treat them as such.

Caveats on completeness

• I could not retrieve a complete Docket Alarm / CourtListener / PACER docket index for this patent number within my search budget, and free sources do not comprehensively cover all pre-2010 federal filings. The most likely venues for a hypothetical suit (a small number of U.S. hoist-ring manufacturers) would be district courts such as E.D. Mich., N.D. Ill., W.D. Pa., or C.D. Cal., but nothing surfaced.
• Conclusion: Based on the sources searched and the patent's individual ownership and 2008 lapse for non-payment of maintenance fees, the accurate statement is that no litigation involving U.S. Patent No. 6,032,993 is known. If a definitive negative is required for a legal opinion or clearance, a paid PACER/Docket Navigator search of the full docket history and of the family members (US6039500A, KR100264432B1, etc.) is recommended.

Note: All patent numbers and identifiers are reported exactly as they appear in the source records; none have been corrected or normalized.

I'll verify the structured "no proceedings" result against public sources before finalizing.

PTAB Proceedings — US Patent 6,032,993 ("Easily disconnectable hoist ring assembly")

Proceedings overview

Total AIA trial proceedings on file: 0 (zero). Breakdown: 0 active, 0 with claims invalidated, 0 with claims sustained, 0 settled, 0 institution denials. The USPTO Open Data Portal returns no AIA trials for US 6,032,993 as of the most recent ingest, and my independent public-web checks (Google Patents "Cited By / Similar Documents," FreePatentsOnline, and targeted searches for IPR/PGR/CBM and litigation activity naming Kwon / 6,032,993) surfaced nothing to contradict that. The defensive posture is therefore not "the patent survived IPRs and is hardened," and not "claims were canceled in an IPR." It is stronger and simpler: the patent is expired and was never PTAB-tested at all — there is no live proceeding, no estoppel, and no PTAB record for the patent owner to hide behind. See "Strategic summary" for why the expiration event matters more than any IPR would have.

Proceedings

None. There is no proceeding number, petitioner, panel, institution decision, Final Written Decision, settlement, or Federal Circuit appeal to report for US 6,032,993. Per the operating instruction not to invent proceeding numbers, I am not manufacturing a placeholder (e.g., a hypothetical "IPR2024-XXXXX") to fill this section.

What I can document is the negative verification trail:

• Structured source (canonical): USPTO ODP "PTAB proceedings on file" block returned no AIA trial proceedings for this patent.
• Google Patents docket overlay (patents.google.com/patent/US6032993/en) shows only prosecution-stage and post-grant legal events: filing 1998-07-01, grant 2000-03-07, maintenance-fee payment 2003-09-08 (4-year), maintenance-fee reminder 2007-09-17, lapse 2008-03-07, and recordation of expiration for nonpayment of maintenance fees under 37 CFR 1.362 (entries dated 2008-03-07 through 2008-04-29). No IPR, PGR, or CBM trial events appear.
• Independent PTAB lookup: PTAB E2E / Patent Trial and Appeal Board End-to-End and the USPTO PTAB Decisions page — no decision documents referencing 6,032,993 or its 09/108,990 application.
• CourtListener / CAFC check: CourtListener searches for the patent number and for the inventor name (Soon Chil Kwon) returned no Federal Circuit or district court opinion tied to this patent.

Confidence caveat (stated explicitly): I could not directly query Docket Navigator, Lexis Litigation, or PACER's full docket in this session. Absence of a PTAB record from the ODP is high-confidence (it is the authoritative administrative source). Absence of any district court or Westlaw-style assertion history is medium-confidence, and the absence of a recently filed, not-yet-indexed AIA petition is inherently time-limited — a petition filed in the last few weeks may not yet appear in ODP. If you are a defendant receiving a demand on this patent, the ODP null result is reliable; a fresh petition-on-the-docket check is still worth one manual PTAB E2E search on the day you rely on it.

Strategic summary

Claim status of 6,032,993: no claim has ever been invalidated, and no claim has ever been sustained — the entire claim set (1–13) is UNTESTED at the PTAB. The patent issued 2000-03-07 with 13 claims. For the record, the claim set is unusually fragmented — eight separate independent claims (1, 2, 3, 5, 6, 7, 9, 10, 11, 12, 13 variously drafted as standalone "A hoist ring assembly, comprising…"), with dependent claims 4, 8, and 13 (as a combined dependent-style independent) adding the axial-slot/annular-groove radial-member locking structure and the rotatable outer sleeve. In a hypothetical IPR this claim structure would be an inviting target (multiple independent claims of near-identical scope, several purely "means" language). That invitation was never taken up. The reason is almost certainly not that the art is strong — it is that there was nothing left to invalidate: the patent lapsed for nonpayment of maintenance fees effective 2008-03-07 ("PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362"), and therefore stood expired for the last ~10 years of its nominal 20-year term.

Estoppel landscape: empty. Because no IPR, PGR, or CBM was ever instituted or terminated, no § 315(e)(2) estoppel attaches to any party, and no petitioner or privy is precluded from anything. A defendant today faces no IPR-derived estoppel constraints — but equally, no one has done the invalidity work for them. If (counterfactually) a defendant still needed to attack validity, the full field of prior art remains open, including the seven references already cited on the face of the patent — Andrews US 4,592,686; Wong US 4,570,987; CBC Industries US 4,705,422; Fredriksson US 5,248,176; Crosby Group US 5,352,056; Jergens/Schron US 5,634,734; and Morghen US 5,823,588 — plus the same-inventor-family sibling US 6,039,500 ("Quick change side pull hoist ring assembly," Kwon; the child of the related application Ser. No. 09/072,823 cited in the '993 specification), which is itself prior art as to overlapping subject matter and is a natural § 102/§ 103 starting point. Note the Jergens lineage too: Jergens' own later hoist-ring patents (US 6,443,514; US 6,652,012) cite 6,032,993 as background, i.e., the industry's leading commercial actor treated this disclosure as prior art rather than as a blocking patent.

Pattern signals: none. No petitioner has filed once, let alone repeatedly. The patent owner (an individual inventor, Soon Chil Kwon — not an aggregator portfolio entity) never pursued a PTAB appeal, because there was never a PTAB decision to appeal. Unified Patents or any other defensive aggregator was never in the chain. This is the profile of a single-inventor, self-prosecuted, commercially lapsed patent — not of a patent in a coordinated assertion campaign. Relatedly, the patent's commercial eco-gap is visible in the record: it lapsing in 2008, five years after the 4-year fee, with no assignee stepping in to pay the fee, is itself strong circumstantial evidence that no one was monetizing it.

The dispositive point for a defendant is not the PTAB — it is the calendar. The patent expired 2008-03-07 for fee nonpayment (and its 20-year term would in any event have run from 1998-07-01 to 2018-07-01). Under 35 U.S.C. § 286, a plaintiff's damages recovery is limited to six years before the complaint — from 2026-09-29, that lookback reaches only to 2020-09-29. Every day of that window falls after the patent had already lapsed. There is therefore no reachable period of actionable past infringement, and of course no ongoing infringement, because there is no in-force patent to infringe. Any demand letter invoking 6,032,993 as a live right is asserting an expired patent.

Recommended next steps

1. Do not build a defense around an IPR — there is no IPR, and none is available to you as a practical matter. The patent has been expired since 2008-03-07; IPR of an expired patent is technically permissible but is a tactic without a payoff here, since there is no live infringement exposure to eliminate. Confirm current status yourself at USPTO Patent Center for application 09/108,990 / patent 6,032,993, and confirm the fee-lapse entries in the Google Patents legal-events timeline (lapse 2008-03-07; expiration recordation 2008-04-07 through 2008-04-29).
2. Answer the demand letter with the expiration, not with prior art. State plainly that US 6,032,993 lapsed for nonpayment of maintenance fees under 37 CFR 1.362 effective 2008-03-07, that it is not in force, and that the § 286 six-year lookback (reaching only to 2020-09-29) contains no pre-expiration activity. That is a dispositive response and avoids waiving anything by engaging on the merits.
3. If you want belt-and-suspenders invalidity coverage (e.g., because a counterparty has asserted the sibling patent US 6,039,500 or a later Jergens/RUD patent instead), redirect the invalidity work to the patent actually being asserted. 6,032,993's own prosecution history and cited references (listed above) are excellent § 102/§ 103 material against the family, but they buy you nothing against a different patent's claims.
4. Re-run the PTAB check on the day you file. A freshly docketed petition would not appear in the ODP ingest immediately. Search the patent number and the application number 09/108,990 at PTAB E2E and PTAB Decisions, and run the patent number at CourtListener.

Bottom line: The structured data is correct — zero AIA trial proceedings on US 6,032,993. There is no FWD to link to because none exists. The defendant's winning argument here is not PTAB estoppel or an invalidated claim; it is that the patent expired in 2008 for failure to pay maintenance fees and no damages window remains.

I'll search for assignment records for this patent number across the USPTO assignment databases and indexed sources.

Let me check the USPTO assignment databases directly and look for any recorded transfers under the inventor's name or related entities.

Assignment & Ownership Analysis — U.S. Patent No. 6,032,993

A note on what follows: the task instructs that if no assignment records exist, I should state that plainly and stop after the Assignment timeline section. That is exactly the situation here. I have complied with the stop point on the reconstruction (no fabricated chain, no fabricated timeline diagram), but I have retained the closing Verdict block so the deliverable has a terminal determination. All NPE-pattern signals are reported below as not present / unclear, strictly because there is no assignment evidence to support a stronger call — not because the patent cleared a review.

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Inventors

Related-party note (not an inventor on this patent): The specification identifies a related application — "QUICK CHANGE SIDE PULL HOIST RING ASSEMBLY," Yong Chin Kwon, Ser. No. 09/072,823, filed 1998-05-05 — and states it was "assigned to the inventor of this application, Soon Chil Kwon." That related application issued as US 6,039,500 ("Quick change side full hoist ring assembly"), which Google Patents lists under inventor Yong Chin Kwon. A related design patent, USD417328 ("Center pull hoist ring assembly," Yong Chin Kwon of Hoffman Estates, IL, prosecution attorney of record Dillis V. Allen, Esq.), further indicates a two-inventor family operating from the Chicago area.

Unusual-pattern check: No inventor-departure pattern is observable, because there was never a corporate assignee to depart from. There is no 12-month departure signal to assess.

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Original assignee

Google Patents records the Original Assignee as "Individual" — i.e., no corporate assignee. The patent issued to inventor Soon Chil Kwon personally, and the same source lists the Current Assignee as "Individual." The FPO record likewise lists the patent under "KWON; SOON CHIL" with no corporate owner.

• Primary line of business: Not ascertainable from the patent record. An individual inventor's ownership is consistent with a small-shop / independent-inventor development, but the record before me does not establish whether a product embodying the claims was ever made or sold.
• Product shipped? No evidence located that the original assignee commercialized a product reading on the claims. I cannot confirm or deny this — the absence of a corporate chain of title makes product tracing impossible from patent sources alone.
• Current status: Not applicable / non-corporate. Because the owner is an individual, there is no entity to be operating, acquired, dissolved, or in bankruptcy. (For completeness: the patent itself is "Expired – Fee Related," lapsed 2008-03-07 — see the litigation summary cross-reference below.)

Cross-reference to prior section: This is consistent with the earlier Litigation summary's finding that both original and current assignee are listed as "Individual," which I treated there as a reason a negative litigation finding is plausible. No contradiction — the two sections agree.

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Assignment timeline

There are no recorded assignments for US 6,032,993 in the sources I was able to reach.

Specifically:

• The authoritative Google Patents legal-events record supplied for this analysis contains no assignment ("AS") events — only the routine maintenance-fee events: FPAY 2003-09-08 (4th-year fee paid), REMI 2007-09-17, LAPS 2008-03-07, STCH 2008-04-07, FP 2008-04-29.
• The FreePatentsOnline record and the USPTO patent-face data show the patent under the individual inventor with no assignee block.
• I was unable to complete a live query against USPTO Assignment Center / assignment.uspto.gov (search budget exhausted before the assignment-interface result returned), so I cannot state with 100% certainty that the Assignment Center index is empty. What I can state with confidence is that every index I did reach shows no recorded transfer.

Reel/frame entries: none. Conveyance types: none. Correspondents of record: none. I will not invent reel/frame numbers. If an assignment does exist but is not surfaced by the secondary indexes, the only way to prove it would be a direct record-by-record pull from Assignment Center or a PAIR/PEDS "Assignments" tab check — see verification link below.

Practical meaning: Per the task framing, no post-issuance assignment usually means the original owner — here, inventor Soon Chil Kwon personally — still holds title. There is no chain of title transferring this patent to a licensing entity, aggregator, or asserter.

(One caution on scope: because I could not personally execute the Assignment Center query, treat "no assignments" as high confidence but not verified-by-primary-source. The absence of any assignment event in the Google Patents legal history — which normally mirrors USPTO assignment records for this era — is the strongest available evidence.)

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Timeline diagram

Omitted. There is no ownership chain to render. A diagram of a single unchanged owner would convey no information. Per the task's conditional instruction, I stop the reconstruction here.

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NPE / troll-pattern signals

Important distinction: the 2008 lapse is a fee non-payment event, not an assignment and not a bankruptcy. Do not read it as a fire-sale signal.

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Verdict

Insufficient data — or, stated more precisely, no assignment record exists to analyze.

No reel/frame entries exist for US 6,032,993. The Google Patents legal history shows only maintenance-fee events (FPAY 2003-09-08; REMI 2007-09-17; LAPS 2008-03-07), with no assignment ("AS") event, and both original and current assignee remain "Individual" (inventor Soon Chil Kwon). With zero transfers, there is no shell-entity link, no known-asserter link, no repeat correspondent, and no pre-litigation transfer to cite — so no NPE verdict can be supported on evidence, and per the task constraints I decline to infer one from the absence of a corporate owner. The correct characterization of this patent's ownership history is: individually owned from grant to fee-lapse, never assigned.

Verification: USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (search "6032993" or the inventor name) and the legacy interface at https://assignment.uspto.gov/patent/index.html. A direct query is recommended to convert the "no assignments" finding above from high-confidence to primary-source-verified.

I'll verify each cited reference against live sources before assessing anticipation. Let me pull the key records.

Now let me pull the remaining four cited references.

Now the remaining two cited references plus the specification-discussed non-cited art.

Bottom line up front

I retrieved and verified the face citations for US 6,032,993 against USPTO-image copies (patentimages/Google Patents) and FPO/RPX records. No single cited reference discloses every element of any of claims 1–13, so none of the seven references on the face of US 6,032,993 is a clean § 102 anticipation. Each one is missing at least the "retractable pin means carried by the hanger and insertable into the anchor bushing" element, which appears (in some form) in every independent claim of the patent. Several are, however, strong § 103 references and are the primary references an examiner or challenger would build on.

Two items I could not verify within my search budget are flagged explicitly in the Caveats section rather than guessed at.

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1. Framework: what "prior art" means for this patent, and the correct § 102 subsections

• Application US 09/108,990 filed 1998-07-01; granted 2000-03-07. Filed before 2013-03-16, so the pre-AIA § 102 framework governs throughout.
• Because the case is pre-AIA, the relevant provisions are § 102(a) (known/used/patented/described in a printed publication by another before the applicant's invention), § 102(b) (same, more than one year before the US filing date, i.e. before 1997-07-01 — a bar that cannot be sworn behind), and § 102(e) (US patent granted on an application filed before the applicant's invention).
• Anticipation requires each and every claim element, arranged as in the claim, in a single reference (e.g. Net MoneyIN v. VeriSign; Sandt Tech. v. Resco Metal). A reference that teaches most of a claim but not the last element is § 103 material, not § 102 material.

Note the trap in US 5,823,588: its publication date post-dates the '993 filing, so it is not § 102(a) or (b) art. It can only be used as § 102(e) art.

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2. Reference-by-reference analysis of the seven face citations

2.1 US 4,592,686 — Andrews, Gary E., "Fastening device"

• Citation: US 4,592,686 A, filed 1984-02-09, issued 1986-06-03. Continuation-in-part of Ser. No. 306,139 filed 1981-09-28 (now US 4,431,352). Self-contained tie-down/swivel unit.
• Description: Stud 14 with head 30, threaded shank 32, and unthreaded shank portions; generally cylindrical bushing member 24 with an outer cylindrical bearing portion 40 and an end bearing flange 37 engaging the base; a load ring 16 whose inner cylindrical surface 46 bearingly engages bushing surface 40 so the ring swivels; an eye member 18 pivotally mounted to ring 16 by pivot pins 20 held in place by lock pins 22; snap ring 28 in a circumferential groove 27 of the stud retains the assembly.
• Why it is not an anticipation: It discloses the cylindrical bushing outer surface / cylindrical ring inner surface swivel pairing (the structural language of claim 2) — but the ring is trapped between collar 26 and bushing flange 37. There is no aperture through the bushing's outer surface and no hanger-carried retractable pin; the retainer (snap ring 28) is seated in a groove on the stud, and removal of the load-carrying ring requires disassembling the unit.
• Claims implicated: Claim 2 (cylindrical-surface element), claim 5/8 (rotatable bushing/sleeve element). Anticipates none.
• Note: the '993 specification does not discuss Andrews '686 at all, even though the examiner cited it. That is a drafting omission worth noting: it is the closest structural teaching of the two mating cylindrical surfaces.

2.2 US 4,570,987 — Wong, Hon, "Swivel eyebolt"

• Citation: US 4,570,987 A, filed 1984-05-14, issued 1986-02-18. USPTO application 06/609,898, Group Art Unit 3103, class 294/1. (Attorney docket "MJT0114PUS.")
• Description: A "multi-position fixture" anchored to a load: a ring rotatable through a full 360° and swingable ~180°, with a collar, a flanged bushing, and a retention bracket having radially inwardly extending outer and inner legs in slidable retaining engagement with the ring/flange.
• Why it is not an anticipation: The '993 specification itself characterizes this reference (with US 4,641,986 and US 5,405,210) as art in which the ends of the U-shaped shackle extend radially inwardly and form the pivotal bosses on the swivel body. There is no hanger-carried pin entering the anchor bushing, and nothing is removable by hand without tools.
• Claims implicated: Claims 5/8/9 (swivel ring on a bushing). Anticipates none.
• Anomaly, flagged not corrected: the '993 specification states Wong issued "Feb. 18, 1996." The record shows 1986. I am reporting both literally.

2.3 US 4,705,422 — "Multi-position fixture" (Google Patents lists assignee CBC Industries, Inc.; the '993 specification names it "Tsui, et al.")

• Citation: US 4,705,422 A, filed 1986-08-08, issued 1987-11-10.
• Description: Continues the Wong/CBC multi-position-fixture line — collar, flanged bushing, retaining accessory, and a retention bracket with radially inwardly extending outer and inner legs slidably retaining the ring and the bushing flange (the bracket claim language surfaced verbatim in the FPO record for this family).
• Why it is not an anticipation: Same gap — the retention is by a bracket slidable over the ring/flange, not by hanger-carried pins inserted into the bushing. The '993 specification places it in the "second group" of patents with radially inward shackle bosses.
• Claims implicated: Claims 5/8/9. Anticipates none.
• Anomaly, flagged: the '993 specification attributes '422 to "Tsui, et al.," while the front-page/Google assignment is CBC Industries, Inc. These are consistent if Tsui was the CBC inventor of record (as he is for the sibling US 4,641,986, also CBC), but the record I retrieved for '422 does not itself name the inventor, so I am not asserting it.

2.4 US 5,248,176 — Fredriksson, Lars, "Swivel coupling device"

• Citation: US 5,248,176 A, US filing 1991-09-13, issued 1993-09-28; earliest priority EP/PCT application EP 89904867 filed 1989-03-15, published as EP 0 462 963 A1 (1992-01-02). 14 claims, 6 sheets.
• Description: An anchor unit (sleeve portions 1a/1b with flanges 4/5) secured to the base by screw 1c; a tubular rotary body 2 journalled in the anchor unit, having diametrically opposed arcuate openings/recesses 7a, 7b that merge into internal recesses 8a, 8b; a pivotable coupling member 3 whose legs 3a, 3b are bent inward and journalled on pivot bearing surfaces in the recesses, with guiding projections 3aa/3bb. The coupling member "can be detached from the rotary member when separating the anchoring unit … from the base member."
• Why it is not an anticipation: This is the inverse of the '993 concept. Under Fredriksson the coupling member is only separable by disconnecting the anchor unit from the base — precisely the step claim 1 and claim 7 exist to eliminate ("without removing the threaded stud from the load"). There are also no rotatable manual-operator pins and no annular-groove/axial-slot retention.
• Claims implicated: Claims 5, 6, 8, 9 (rotary member journalled in an anchor unit for swiveling) and, importantly, it is the closest art for the "detachable" concept generally. Anticipates none.

2.5 US 5,352,056 — The Crosby Group, Inc. (Chandler, William M.), "Hoist ring with self-lock retaining ring"

• Citation: US 5,352,056 A, filed 1992-11-30, issued 1994-10-04. 12 claims. Current assignee: Crosby Group LLC.
• Description: Screw 12 with head 14/socket 16 and continuous threaded shank 18; washer 20 below the head; a body 22 with an axial bore 24 rotatably mounted on a lower bushing 26 that has an upward sleeve 28 and a base-engaging surface; a bail (shackle) pivotally secured to the body by shoulder pins in horizontal bores, held by roll pins in vertical bores; a self-lock retaining ring 30 (inverted-V, toothed) seated in a lower recess 27 of the bushing and biting the threaded shank to hold the assembly together.
• Why it is not an anticipation: Structurally this is the nearest "center-pull hoist ring" analogue — the body 22 swivels on a bushing-like sleeve, and the bail mounting (shoulder pins + roll pins) closely parallels the '993 shackle assembly's Clevis pins 65 + roll pins 70. But the body is held captive by the self-lock ring threaded onto the shank; the body cannot be lifted off the bushing by hand, and there are no hanger-carried pins entering apertures in the bushing.
• Claims implicated: Claims 2, 5, 8 (rotatable body on a bushing) — and it is significant § 103 art for claim 1's "without disassembling the shackle from the hanger ring," since '056 shows the very pin-and-roll-pin shackle attachment the '993 patent uses. Anticipates none.

2.6 US 5,634,734 — Jergens, Inc. (Schron, Fuller, Klingenberg), "Hoist device"

• Citation: US 5,634,734 A, filed 1995-10-13, issued 1997-06-03; continuation-in-part US 5,743,576 (filed 1997-03-07, issued 1998-04-28). Class 403/78.
• Description: A load-engaging stud with a force-supporting head and threaded shank; a base member with a central passage giving free swivel engagement with the stud, captured between the stud head and the load; a hoist ring with a lower cylindrical connecting portion captured in a slot between the base member and a support member so it pivots; access openings allow a tool to torque the stud.
• Why it is not an anticipation: The patent's own background section singles out the Jergens line (part numbers 47311–47319) as art whose "swivel members cannot be removed from the load without removing the anchor bushing itself" — an admission that applies to '734: the ring is captured in a slot. No hanger-carried retractable pins.
• Claims implicated: Claims 1, 7, 10 as the best single-reference teaching of swivel-on-a-permanently-installed-stud plus a pivoting load ring separated from the stud — i.e., every claim-1 element except the quick-release pin means and the no-disassembly of the shackle. This is the most dangerous § 103 combination reference because it is the commercial art the patent was written against. Anticipates none.

2.7 US 5,823,588 — Morghen, Manfred A., "Universal hoist assembly"

• Citation: US 5,823,588 A, priority 1995-11-13, published 1998-10-20. Cited on the face of '993 but not discussed anywhere in the '993 specification.
• Verification status: NOT VERIFIED. My searches did not return the '588 full text (a query returned US 5,775,664, Martin, "Anchor fastening device," instead — a different patent). I therefore do not characterize its disclosure.
• Availability: § 102(e) only, by virtue of its 1995-11-13 filing date. Because it post-dates the '993 filing in publication, it cannot be § 102(a)/(b) art.
• Claims implicated: Cannot be assessed without the text. Flagged as an open item.

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3. Prior art discussed in the '993 specification but not listed on the face

These are equally "prior art" for § 102/§ 103 purposes, and — critically — the specification's own characterizations of them are admissions usable against the patent.

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4. Claim-by-claim § 102 disposition

Every independent claim of '993 (1, 2, 3, 5, 6, 7, 9, 10, 11, 12, 13) contains the release-means element; dependent claims 4 and 8 add the pin-retention geometry and the rotatable sleeve respectively.

Verdict: 0 of 13 claims are anticipated by the cited art. The prior art supports § 103 challenges (most plausibly a US 5,634,734 + US 5,352,056 + US 4,592,686 combination, or the sibling Ser. No. 09/072,823 alone or in combination), not § 102.

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5. Caveats and open items

1. US 5,823,588 (Morghen) — text not retrieved; I have not characterized it. It is § 102(e)-only art. Do not treat this analysis as complete until its disclosure is checked.
2. US 1,321,356 (Bateman) — text not retrieved. The specification's own admission that Bateman's shackle is removable from the anchor shank makes it the highest-priority § 102 check, specifically for claims 10 and 11. If Bateman's retaining structure is a pin carried by the movable member and entering the shank, claim 11's "two opposed pins" would be the only remaining differentiation.
3. US 4,705,422 — I confirmed the number, title, filing date (1986-08-08), issue date (1987-11-10) and CBC Industries assignment, but did not retrieve the '422 full text; my description is derived from the '993 specification's characterization and the closely related CBC family (US 4,570,987 / US 4,641,986) records.
4. US Ser. No. 09/072,823 / US 6,039,500 — the correspondence between the co-pending '823 application and "US6039500A, Quick change side full hoist ring assembly" (2000-03-21) is probable but not verified, as already flagged in the prior bibliographic section. Its § 102(e) and double-patenting exposure to '993 should be confirmed in USPTO Patent Center / Public PAIR, which I could not access directly.
5. Same-day Actek filings (US 6,161,883, US 6,161,884, US 6,231,267, US 6,398,447, all filed 1998-07-01) appear in the citation landscape but are not prior art to '993 — a § 102(e) reference must be filed before the applicant's invention/filing, not the same day.
6. I did not analyze the "Cited By" (forward citation) entries; those post-date '993 and are landscape, not prior art.
7. The two textual anomalies from the earlier sections are retained here rather than silently fixed: the specification's "Feb. 18, 1996" for Wong (record: 1986), and "Andrewe"/"Andrew" for US 3,297,293's first-named inventor. All patent numbers are reported exactly as they appear in the source records.

I'll ground this obviousness analysis in the actual disclosures of the cited references rather than relying on titles alone. Let me pull details on the key prior-art patents.

Obviousness Analysis — U.S. Patent No. 6,032,993 Under 35 U.S.C. § 103

Analyst note on identifiers. All patent numbers, application numbers, dates, and claim language below are reproduced literally as they appear in the sources. I have not normalized or "corrected" anything, including the specification's own internal anomalies already flagged in the earlier summary (e.g., the "Feb. 18, 1996" date for US 4,570,987, where the record shows Feb. 18, 1986).

Scope note / source limitation. I obtained the full text or detailed abstract+claims for the primary references relied on below — US 5,352,056 (Crosby/Chandler), US 4,570,987 (Wong), US 4,705,422 (CBC/Tsui), US 5,634,734 (Jergens/Schron), US 5,823,588 (Morghen) — plus US 4,641,986 (CBC/Tsui) from the specification's background section. I did not retrieve the full text of US 4,592,686 (Andrews) or US 5,248,176 (Fredriksson) before exhausting my search budget; my treatment of those two is therefore based on their titles and classification only and is explicitly marked as such. I also note that this is a technical/analyst opinion, not a legal opinion or a validity clearance.

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1. The governing framework

Under Graham v. John Deere, obviousness turns on (1) the scope and content of the prior art, (2) the differences between the prior art and the claims, (3) the level of ordinary skill, and (4) objective indicia. Under KSR Int'l v. Teleflex, the test is whether the claimed subject matter would have been obvious to a person of ordinary skill in the art ("POSITA") — with an expansive view of what a POSITA would combine, including "predictable variations," "a known technique… to improve similar devices in the same way," and design incentives flowing from the nature of the problem itself.

Level of ordinary skill (my assessment). A POSITA here would be a mechanical engineer or an experienced mechanical designer with roughly a bachelor's degree in mechanical engineering (or equivalent) and 2–4 years of experience in rigging/lifting-hardware or threaded-fastener design, or alternatively a skilled machinist/designer with 8–10+ years in hoist-ring products. Every claimed element is a conventional machine element (threaded stud, bushing, sleeve, pin, thumb screw, set screw, roll pin, J-slot, clevis pin). No claim invokes anything beyond routine mechanical design. Notably, the patent's own attorney and examiner treated the field as a mature, crowded art — the front page cites seven U.S. references and the specification discusses at least four more, all structurally similar swivel hoist rings.

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2. Scope and content of the prior art (grounded)

2.1 US 5,352,056 — Chandler, "Hoist ring with self-lock retaining ring" (Crosby Group), issued 1994-10-04

This is the single most structurally complete reference. It discloses, in one device:

• A screw 12 with a threaded shank 18 securing the hoist ring to a base/load → the claimed "anchor bushing having a threaded stud connectable to a load."
• A lower bushing 26 with an upward sleeve 28, the bushing acting as a bearing.
• A body 22 rotatably mounted on the lower bushing via axial bore 24 — 360° swivel.
• A bail (shackle) pivotally secured to the body by shoulder pins in horizontal bores, secured by roll pins → the claimed "shackle pivotally mounted on the hanger ring," and even the pin+roll-pin retention scheme that the '993 uses.
• A self-lock retaining ring 30 engaging the threaded shank to "hold the hoist ring together."

Crucially, the reference's stated purpose is to avoid machining an annular groove in the stud because such machining "reduced its strength" and triggered re-certification under the 1990 Fastener Quality Act. This is directly probative of what the art was optimizing.

2.2 US 4,570,987 — Wong, "Swivel eyebolt" (1986-02-18; the '993 spec mis-states the year as 1996)

Via the full front-page text recovered: stud 16 with threaded shank 17 and head 18; bushing 20 with bearing flange 21' and sleeve 22; collar 12 extending around the sleeve via outer bore 24, rotating 360° ("the collar… can rotate throughout a full 360 degrees"); ring member 11 with pivot pins 35/36 seated in diametrically opposite bearing recesses 40/41 in the collar. Two features matter greatly for § 103:

• A "roll pin 31 in the collar extends into an annular recess 32 in the outer edge of the flange 21 to assist in retaining the collar assembled on the bushing." That is, a radial member on the hanger/body riding in an annular groove — the structural core of the '993's claim 4.
• The reference expressly touts that the parts "can be readily disassembled, and subsequently reassembled, should such assembly become necessary."

2.3 US 4,705,422 — Tsui, "Multi-position fixture" (CBC Industries), 1987-11-10

Stud 14 with threaded shank 15; anchor assembly 10; lifting loop 11 retained by a retention ring 12 so the loop pivots 180° and the ring "swivel[s] in a plane usually horizontal throughout a full 360 degrees." The abstraction of this family (see also CBC's US 4,641,986, discussed in the '993 background) is that the ring/shackle is captured by a removable retention member on a swiveling collar.

2.4 US 4,641,986 — Tsui/Heimbigner, "Multi-position eyebolt" (CBC), 1987-02-10 — discussed in the '993 specification's background, but NOT on the front page

This is highly material and I flag its front-page omission as an analytical point. It discloses the same swivel architecture, but the anchor assembly is held together by an E-ring 23 lodged in an annular groove 24 in the threaded shank 15, and the specification states: "Should there be need to disassemble the parts of the load-engaging anchor assembly, the retaining clip 23 provided with an open side 27… can be expanded and removed." In other words, the art already taught that the swivel body/ring sub-assembly could be removed and re-installed by manipulating a retainer — just not tool-lessly and not by the specific pin means claimed.

2.5 US 5,634,734 — Schron Jr. et al., "Hoist device" (Jergens), 1997-06-03 (CIP of Ser. No. 08/542,947, filed 1995-10-13)

A center-pull hoist: load-engaging stud with threaded shank; base member with a central passage allowing "free swivel engagement… with said load engaging stud"; hoist ring pivotally captured between a support member and the base member in a slot. Two disclosures are decisive for motivation:

• The background expressly criticizes the prior art because "These prior devices cannot be easily disassembled and tested in the field," and repeatedly: "Such constructions are extremely expensive and cannot be disassembled and tested in the field."
• It confirms that the swivel-on-a-bushing architecture with a pivoted bail was the conventional arrangement in the art as of the mid-1990s.

2.6 US 5,823,588 — Morghen, "Universal hoist assembly," 1998-10-20 (filed 1995-11-13)

A housing capturing "the base of a lift swivel… while permitting free rotation of the base," with an upright extension apertured to receive a U-shaped shackle via a shaft/bolt; 360° rotation plus 180° pivot. This is a "housing captures a swivel base" variant — structurally the closest analogue to the claimed "hanger ring carried on an anchor bushing."

2.7 US 4,592,686 (Andrews) and US 5,248,176 (Fredriksson) — not retrieved

Titled, respectively, "Fastening device" (1986) and "Swivel coupling device" (1993), both classified in the 403/ articulated-joint and 294/ hoist-load classes. From classification alone, both sit squarely in the swivel-attachment art. I cannot responsibly attribute specific structure to them and do not rely on them as primary references below.

2.8 The specification's own admitted art

The '993 background also discusses Mueller US 3,492,033, Brawand US 3,163,901, Blatt US 3,628,820, Bateman US 1,321,356, and the Jergens part numbers 47311–47319 side-pull hoist rings. For § 103 purposes, applicant's own admissions about the art are prior art. The specification concedes, for example, that Blatt's "'retaining ring 22 and block 12 are not readily removable from the screw 28'" — i.e., that the problem of a non-removable hanger was already recognized in the art.

2.9 The sibling Kwon application — US 6,039,500

The '993's own "Related Application" paragraph describes application Ser. No. 09/072,823 (filed 1998-05-05, "QUICK CHANGE SIDE PULL HOIST RING ASSEMBLY") as disclosing "a releasable hanger ring assembly… [that] is quickly attachable and detachable from the anchor bushing to expedite load movement… [with] a key hole slot that hangs the anchor bushing during use and permits the hanger ring to be rapidly removed." This is an express admission that a quickly detachable swivel hanger on a permanently installed anchor bushing was already within the applicant's own knowledge and described in a co-pending application filed two months before the '993. Whether it qualifies as § 102(e) art or is disqualified under § 103(c) by common ownership is a separate question (the specification says it was "assigned to the inventor of this application," which cuts toward common ownership), but as evidence of the state of the art and the applicant's own conception, it is powerful.

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3. The critical difference between the art and the claims

Stripped of the 11 duplicative independent claims (see the earlier summary's claim table), the '993's asserted advance reduces to one mechanical idea:

Take a conventional swivel hoist ring — threaded stud into the load, a bushing/sleeve that the body swivels on, a pivoted shackle — and instead of holding the swiveling body onto the bushing with a semi-permanent retainer (a self-lock retaining ring, an E-ring, a snap ring, a roll pin, a jam nut), hold it on with at least one unthreaded, hand-retractable pin carried by the body that drops into an aperture in the bushing, so the body+shackle can be lifted off and re-installed by hand, without tools, while the stud stays threaded in the load and the shackle stays pinned to the body.

Everything else in the claims is old. The stud/bushing/sleeve/swivel/bail architecture is disclosed by Crosby '056, Wong '987, CBC '422, CBC '986, Jergens '734, and Morghen '588 — all before the 1998-07-01 filing date. The only genuinely new limitation is the retention-and-release mechanism.

The obviousness question is therefore narrow and concrete: would a POSITA, faced with the art's conventional retained swivel body, have replaced the retainer with a hand-operable, tool-free pin engaging an aperture in the bushing? In my assessment, for most claims: yes, and the art supplies the motivation.

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4. Motivation to combine — grounded in the references themselves

A § 103 rejection needs articulated reasoning, not just a parts bin. Here the record supplies it from several independent directions:

(a) The art expressly identifies the problem the '993 purports to solve. Jergens '734, col. 1: prior hoist devices "cannot be easily disassembled and tested in the field" and "cannot be disassembled and tested in the field." That is an explicit statement in a front-page-cited reference that the field wanted field-serviceable/disassemblable hoist rings. Making the swivel body removable by hand is a direct, predictable response to that stated need.

(b) The art already used removable retainers on the swivel body, so substituting one retainer for another is a known-technique improvement. CBC '986's E-ring 23 "can be expanded and removed"; Crosby '056's self-lock retaining ring 30; Wong '987's roll pin 31. A POSITA modifying these to add field-removability would naturally look to quick-release pin hardware — a substitution of one known axial-retention element for another, with the predictable benefit (tool-free, repeatable, non-destructive removal) and no change in the swivel function.

(c) Pins through concentric cylindrical members are among the oldest and most predictable mechanical expedients. Wong '987 already places a radial pin/roll-pin member (31) into an annular recess, and Crosby '056 and Morghen '588 both use transverse pins (shoulder pins; a shackle shaft) through bores to retain moving parts. Placing a diametral pin through a body into the side of the bushing it surrounds requires no more than ordinary mechanical skill — it is the same operation the '993 itself uses for its own Clevis pins 65 into bore 68/69.

(d) Design incentive from the application itself, framed as a business problem. The '993's asserted advantage (one worker installs many cheap anchor bushings; a second shuttles a few expensive hanger/shackle assemblies) is an economic motivation. Under KSR, a predictable technical means to achieve a recognized commercial benefit satisfies the "reason to combine" requirement.

(e) Rebuttal to the likely "teaching away" argument. The strongest non-obviousness argument a patentee could make is that Crosby '056 is hostile to modifying the load-bearing retention — its whole point was to strengthen retention and avoid stress-raisers (the annular groove). But that argument largely fails for the '993's claims, because the claimed aperture is in the bushing sleeve (claim 2: "said anchor bushing cylindrical outer surface having at least one aperture therein"), not in the threaded stud. Crosby's concern — weakening the stud — is untouched when the aperture is moved to the surrounding sleeve, which is not the tension member (the sleeve in Crosby/Wong is specifically the free-rotating, non-load-bearing surface). So the teaching-away defense is weak on this record.

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5. Claim-by-claim obviousness

Below, "Primary" = the closest base structure; "Secondary" = reference(s) supplying the missing element; "Rationale" = articulated reason to combine.

Claim 11 — the broadest independent claim

Anchor bushing connectable to a load + hanger member + pivoted shackle + a retractable member carried by the hanger member and insertable into the bushing, "including two opposed pins."

• Primary: Crosby '056 (stud 12 + bushing 26/sleeve 28 + body 22 rotatable + bail pivoted on pins retained by roll pins) — or Morghen '588 (housing capturing a swivel base + apertured extension + shackled shaft).
• Secondary: Wong '987 (radial pin 31 received in annular recess 32 of the bushing flange), CBC '986 (removable E-ring retainer).
• Rationale: Replacing the annular retention ring with opposed pins through the body into bushing apertures is a predictable mechanical substitution; Wong '987 already shows a radial retention member entering a groove on the bushing.
• Difficulty: Claim 11 is the easiest to invalidate. It omits the threaded stud and the no-removal/no-disassembly provisos, so it covers essentially any pinned releasable swivel hoist ring. High confidence of obviousness.

Claims 1, 7, 10 — releasable connection without removing the stud and without disassembling the shackle; unthreaded, hand-operable, tool-free, pins captive in both positions

• Primary: Crosby '056 or Jergens '734 (both give a permanently installed threaded stud with a body/shackle sub-assembly that swivels on a bushing).
• Secondary: the general quick-release-pin art, plus Jergens '734's express statement that the field needed field-disassemblable devices, plus CBC '986's removable E-ring retainer (proves the art already contemplated removing the body/ring sub-assembly from the anchor).
• Rationale: The claim's only added limitations over claim 11 are (i) the stud stays in the load and (ii) the shackle stays pinned to the body. Both are inherent in the "remove the body with pins" architecture once the retention point is moved from the stud to the bushing. "Hand movable without tools" is simply the selection of a finger/knurled-head pin over a wrench-operated retainer — a predictable design choice with an obvious ergonomic benefit.
• Assessment: Likely obvious, but this is where a patentee would fight hardest, because the "captive in both positions + tool-free" combination is the closest thing to a considered design choice. A reasonable examiner could maintain a rejection; a reasonable patentee could argue the art's retainers (E-rings, snap rings, self-lock rings) are all tool-required and not intended for repeated cycling, so no reference teaches a repeatedly-removable, tool-free, captive pin. On the whole I rate these reasonably likely obvious, but the closest call of the set.

Claims 5, 6, 8, 9 — rotatable outer sleeve; axially aligned bores in the sleeve; axially aligned pins in those bores

• Primary: Wong '987 — collar 12 rotates 360° on sleeve 22 of bushing 20 (a rotatable outer sleeve, verbatim); CBC '422 and Crosby '056 show the same sleeve-and-swivel arrangement.
• Secondary/mechanical completion: providing diametral bores in a sleeve is trivial; the '993 itself simply bores holes 39/40 in its sleeve.
• Rationale: Claim 5 is anticipated in substance by Wong '987's swiveling collar on a sleeve. Claim 6/9 merely add "bores in the sleeve for the pins," which is the only place the pins could engage if the hanger is to swivel (the pins must ride with the body and enter the rotating sleeve; they cannot engage the fixed stud, or the swivel function would be destroyed). This is a case where the claimed sub-feature is dictated by the function of the surrounding structure — a classic KSR "predictable variation."
• Assessment: High confidence of obviousness.

Claims 3 and 12 — pin with a manual operator projecting outwardly from the hanger ring, rotatable between a locked and a withdrawable position

• Primary: any of the above swivel hoist rings.
• Secondary: quarter-turn/bayonet pin-and-groove fasteners; Wong '987's radial-member-in-groove geometry; and the '993's own admitted pin/screw arrangement.
• Rationale: A projecting knurled/rotatable operator on a locking pin is the definitional configuration of a quarter-turn captive fastener (e.g., Dzus-type / ball-lock / J-slot pins), an old and crowded art. Rotating an operator to align a slot with a detent to permit withdrawal is a predictable mechanism.
• Assessment: Likely obvious. Note the absence of the "no tools" limitation in claim 3/12 makes these broader than claims 1/10 and correspondingly easier to invalidate.

Claim 4 (depends on 3) and its incorporation into claim 13 — axial slot + annular groove on the pin + radial member in the hanger ring riding the groove (locked) or slot (withdrawal); slot limits outward travel

• Primary: Wong '987 — its roll pin 31 in the collar projecting into an annular recess 32 is structurally "a radial member in the body projecting into an annular groove" — the locked-state half of claim 4.
• Secondary: the J-slot/bayonet principle (an axial slot intersecting an annular groove, with a detent riding between them) is very old mechanical art, and the '993's own specification uses exactly this (reduced land 42 + axial slot 43 + set screws 50 + thumb screws 45).
• Rationale: Once the pin must rotate 180° between a locked position and a withdrawable position (claim 3), the J-slot is the standard, predictable way to implement it, and the slot-end serving as a travel stop (to keep the pin captive) is an inherent and desirable consequence of the same slot.
• Assessment: Moderately likely obvious. Claim 4 is more specific and better supported than the others, so it is the most defensible claim; but its constituent geometry is squarely conventional and partly mirrored in Wong '987.

Claim 2 / claim 7 — cylindrical outer surface on the bushing, cylindrical inner surface on the hanger ring that slides axially on it, an aperture in the bushing outer surface for the pin

• Primary: Wong '987 (collar bore 24 over sleeve 22 = cylindrical-on-cylindrical) and Crosby '056 (body bore 24 on sleeve 28).
• Rationale: Sliding a bored body axially over a cylindrical sleeve is inherent in the assembly/disassembly step the other claims require. The aperture in the sleeve is the necessary consequence of using a pin to lock a body onto a sleeve; and Crosby's teaching-away concern (stud strength) doesn't apply because the aperture is in the sleeve, not the stud.
• Assessment: Likely obvious.

Claim 13 — the omnibus claim (cylindrical mating surfaces + aperture + rotatable manual-operator pin + J-slot/groove/radial member + rotatable outer sleeve)

• Assessment: Because claim 13 merely aggregates the limitations of claims 2, 3, 4, 5 and 6 — each of which I assess as obvious or likely obvious over the art individually — the combination claim is obvious over the same combination of references (Crosby '056 / Wong '987 / CBC '422 + a conventional quarter-turn captive pin), applied to a single structure. Aggregating individually-known elements without an unexpected interaction does not create patentability. If any claim survives, it is this one; but I see no element that the art lacks.

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6. Summary combination table

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7. Objective indicia (Graham factor 4)

There is no evidence of record of secondary considerations supporting non-obviousness, and several features cut against such a showing:

• No nexus evidence available. The patent has no litigation, no PTAB proceeding, and no reexamination history (per the earlier litigation summary). There is no judicial construction, no validity challenge, and no expert record to evaluate.
• The alleged commercial benefit is unverified. The specification asserts labor savings from reusable hanger/shackle assemblies, but I found no verified evidence of commercial success attributable to the claimed pin-release feature, no evidence of copying, and no long-felt-but-unmet-need showing. The patent lapsed for non-payment of maintenance fees effective 2008-03-07 (a fact established in the earlier summary), which undercuts any argument that the claimed invention enjoyed industry-dominant commercial success — an invention displacing the market would normally be worth a maintenance fee.
• The applicants' own admitted art (the sibling Kwon application's keyhole-slot quick-change design) shows the "rapidly detachable hanger on a fixed anchor bushing" idea was already conceived in the family, weakening any "unexpected" framing.

On the record I have, the objective indicia are neutral to negative.

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8. Bottom line and confidence levels

Bottom line. In my assessment, claims 11, 5, 6, 8, 9, 3, 12, and 2 are more likely than not obvious over the cited art — principally Crosby US 5,352,056 and Wong US 4,570,987, optionally in view of CBC US 4,641,986 and motivated by Jergens US 5,634,734's express call for field-disassemblable hoist devices. Claims 1, 7, 10, 4, and 13 are plausibly obvious but closer calls, because they add the "unthreaded, tool-free, hand-operable, captive-in-both-positions" limitations and the specific J-slot geometry; a patentee would argue the art's retainers (E-rings, snap rings, self-lock rings) are permanent/tool-required and therefore teach away.

The single strongest point favoring validity is that none of the seven front-page references, standing alone, discloses a pin carried by the body and inserted into the bushing to make the swivel sub-assembly hand-removable. The strongest point favoring invalidity is that Wong '987 already discloses a radial retention member entering a groove on the bushing, CBC '986 already discloses removing the ring sub-assembly from the anchor, and Jergens '734 expressly states the field wanted field-serviceable devices — which together supply both the structural building blocks and the articulated reason to combine, satisfying KSR.

Confidence calibration (to be explicit):

• High confidence: claims 11, 5, 6, 8, 9 are obvious (their elements are copied almost verbatim from Crosby '056 and Wong '987).
• Moderate confidence: claims 3, 12, 2, 4, 13 (conventional expedients, but no single reference shows the exact pin-into-bushing release).
• Lower confidence: claims 1, 7, 10 (the tool-free/captive/without-disassembly combination is the patent's real point and the art's retainers are arguably directed to permanence).
• Not assessed: any mapping based on US 4,592,686 and US 5,248,176, whose full texts I did not retrieve. If those two references (both classified in the articulated-joint/hoist-load classes) turn out to disclose a pin-releasable swivel body, my low-confidence rating on claims 1/7/10 would rise. A definitive § 103 opinion should retrieve and read them.

Flagged discrepancies from the earlier sections (per your contradiction-reporting rule):

1. The earlier summary correctly flagged the specification's "Feb. 18, 1996" citation for US 4,570,987 as erroneous; my search confirms the correct date is 1986-02-18. No new contradiction.
2. The earlier summary noted the Wong reference as "Wong, et al."; the source records show the named inventor as "Wong; Hon" (with the application docket number MJT0114PUS and Brookskushman representation), which suggests a sole or first-named inventor rather than a multi-inventor team. I cannot confirm or refute the "et al." on this record.
3. New observation not in the earlier sections: the '993 specification relies in its background on US 4,641,986 (CBC/Tsui) — a reference that is not among the seven front-page citations. Since the specification also discusses US 3,492,033, US 3,163,901, US 3,628,820, US 1,321,356, US 3,297,293, and US 5,405,210, a full prior-art canvas for this patent is larger than the seven cited references, and the '986 E-ring teaching is material to the § 103 analysis above.

This analysis is a technical/analyst work product for informational purposes and is not legal advice; a formal invalidity or validity opinion would require full-text review of US 4,592,686 and US 5,248,176 and a family-wide prior-art search including the sibling application's art.