US 4911426

I'll verify the patent details against live sources before summarizing.

Let me check for litigation, CAFC dockets, and current legal status.

US Patent 4,911,426 — Verification Summary

Sources checked: Google Patents (US4911426A), FreePatentsOnline, Justia Patents, SumoBrain, plus targeted searches of USPTO/PTAB/CAFC-related material. Where sources agreed, I treated the full patent text as authoritative (per operating rules).

⚠️ Important search caveat: My searches for litigation history returned no CAFC 2026 docket, no IPR, and no district-court case naming U.S. 4,911,426. The only literal "4911426" hits were unrelated (a Brazilian federal court case number and a CourtListener internal ID). I could not access a live USPTO PatentCenter/Assignment record directly, so bibliographic data below is drawn from the patent front-matter as republished by Google Patents, FreePatentsOnline, and Justia. I flag this as moderate-confidence, not primary-source-verified.

Bibliographic Data

(Note: I checked whether any of these identifiers had been auto-corrected — they are as listed in the sources. The filing date 1988-01-07 differs from the CIP parent's 1986 filing and from the 1986-05-22 priority date; the sources label the priority date an "assumption.")

Abstract (as issued)

A therapeutic exerciser system suspended from a horizontal trapezoid frame with a movable balance point, connected by a cleated fiddle block pulley assembly to an overhead beam eye bolt or to a rolling traveler on an overhead track, providing specially developed support sections. A common upper body support is combined with any one of three interchangeable lower body supports — a bucket seat, a crotch piece, or a pelvic support. Range of motion is determined by the user's ability and by the type of lower body support. Usable by a treatment provider to facilitate vestibular stimulation, sensory integration, and other modalities for users who cannot move themselves. The harness is suspended from a trapezoid frame with an adjustable pivot point of balance, allowing body positions from semi-reclined to upright.

Independent Claim — Plain-Language Overview

There is one independent claim (claim 1); claims 2 and 3 depend from it.

Claim 1 — Adjustable overhead harness exerciser kit

• An overhead-mounted, adjustable harness exerciser kit for attachment to an overhead beam.
• Comprises a user support harness made of:
  • an upper body support, and
  • a selected lower body support that is removably attached to the bottom of the upper body support.
• The upper body support is suspended by a plurality of straps from a trapezoid frame.
• The trapezoid frame hangs from the overhead beam via an attachment means comprising a pulley and shock-cord assembly.
• Key structural feature: the attachment means has a positionally adjustable attachment to the trapezoid frame.
• Stated advantage: changing the position of the attachment means along the trapezoid frame changes the pivot point of balance of the harness, giving an adjustable tilt of the user.

Claim 2 (dependent on claim 1) — adds a rolling traveler between the overhead beam and the attachment means, so the attachment means rolls along the overhead beam (enables gait-training / travel along a track).

Claim 3 (dependent on claim 1) — limits the "selected lower body support" to a set consisting of: a pelvic support, a bucket seat, and a crotch section (the interchangeability feature).

Notes on Scope and Uncertainty

• The claim set is narrow and structurally focused: the inventive core recited in claim 1 is the combination of (a) an interchangeable two-part harness, (b) a trapezoid frame, and (c) a pulley/shock-cord suspension whose attachment point is movable so as to shift the balance pivot and tilt the user. Claim 2 adds the rolling traveler; claim 3 recites the three selectable lower body supports.
• The specification's detailed disclosure (zippers/VELCRO waist sizing, FASTEX side-release buckles, LADDERLOC fasteners, ENSOLITE padding, fiddle block/camcleat pulley arrangement) is not captured in the claims; it is enabling/supporting description rather than claimed subject matter.
• I have no authoritative evidence of any assignment to a company, any litigation, any IPR/PGR, or any 2026 CAFC activity involving this patent. Absence of such results in my searches is not proof of absence — treat it as "not found," not "confirmed none."
• The patent is long expired; any current commercial product overlap would be in the public domain.

If you need USPTO-record-grade confirmation (e.g., a certified assignment chain or an Image File Wrapper check), that requires direct PatentCenter/Global Dossier access, which my search tools did not return in this session.

I'll run targeted searches for litigation involving US 4,911,426 specifically.

Let me run additional targeted searches to be thorough, including the inventor name and litigation-specific databases.

Litigation Search — U.S. Patent No. 4,911,426

Bottom line

No litigation involving U.S. Patent No. 4,911,426 has been found. I could not identify any district-court action, CAFC appeal, ITC investigation, PTAB/IPR/PGR proceeding, or foreign counterpart suit naming this patent, its inventor (Mary E. Scales), or any assignee, as a plaintiff or defendant.

⚠️ Date discrepancy to flag: This task states the current date is April 26, 2026, but the system-level operating date is September 22, 2026. My searches surface material dated into mid-2026 (e.g., a June 2026 D. Del. opinion unrelated to this patent). Under either date, the conclusion below is unchanged, but I want to be explicit about the inconsistency rather than silently pick one.

This is consistent with — and re-verifies — the conclusion in the previously generated summary section, which also reported no litigation. No contradiction between the prior section and this one.

Search methodology and literal-ID discipline

Per the strict rule, I searched the patent number literally and did not auto-correct or fold in "similar" numbers (e.g., conflation with 4,911,461; 4,491,426; 5,491,426; or the Australian judgment number [2013] FCA 1426). Every "4911426" hit returned was checked and confirmed to be a false positive — a different identifier that merely shares the digit string:

I also ran subject-matter and party searches (inventor name "Mary E. Scales," "harness exerciser" + infringement, and litigation-database queries). These returned no case tied to this patent; the "Scale Biosciences v. Parse Biosciences" and other results are unrelated companies sharing the word "Scale."

Note on tooling limits: I was not able to directly query portal.unifiedpatents.com/litigation/caselist, PACER, Docket Navigator, or the USPTO PatentCenter/Assignment APIs in this session — my searches repeatedly returned unrelated content for those queries. So the correct characterization is "not found," not "certified none." A negative result from an indirect search is not the same as a cleared docket check.

Why "no litigation found" is the expected result here

• The patent is long expired. Google Patents records the status as Expired – Fee Related, with anticipated expiration 2007-03-27. Any infringement action on the '426 patent would have had to be filed before that date; there is no live enforcement window.

• No corporate owner. The patent lists "Individual" as both original and current assignee (inventor Mary E. Scales). There is no NPE/PAE assignee — the typical driver of serial patent litigation — which sharply reduces the probability of any filed suit.

• The forward-citation ("Cited By") list is large (60+ entries), but that is citation activity, not litigation. Being cited by later patents (e.g., the Bioness/AlterG/Community Products body-weight-support families) means the '426 patent is prior art, not that it was asserted.

• The only IP-office references I found are prior-art citations of the patent, not disputes:

  • EP 1 268 005 B1 (Community Products LLC, "Method and apparatus to exercise developmentally delayed or neurologically impaired persons") cites "US 4911426 A [0010]" in its description — the same family that appears in the '426 "Cited By" list.
  • Design patents such as USD862875 and US 10,213,699 / 11,376,513 list "4911426 | March 27, 1990 | Scales" in their References Cited.

  These are examiner/applicant citations and confirm the patent's status as a widely-cited reference, not as a litigated asset.

Requested case table

Because no litigation was found, there are no entries to populate. For completeness:

No district-court case, no CAFC appeal, no ITC Section 337 investigation, and no PTAB trial (IPR/PGR/CBM) involving US 4,911,426 was located.

Recommended next steps if a definitive answer is required

To convert "not found" into a defensible clearance statement, the following primary sources should be checked directly (I could not reach them in this session):

1. USPTO PatentCenter / Global Dossier for the '426 patent — confirm assignment chain and any litigation-related papers in the file wrapper.
2. PACER / Docket Navigator / Lex Machina — run a "patent number" field search (not full-text), which filters out the false positives above.
3. Unified Patents litigation portal — query the patent number as an exact string.
4. CAFC docket search for any appeal where the '426 patent was the patent-in-suit.
5. ITC EDIS search for Section 337 complaints citing the patent.

If those sources also return nothing, the conclusion is a documented negative: as of the search date, no litigation is known involving U.S. Patent No. 4,911,426.

I'll verify the structured data against live sources before finalizing, since the canonical block states no AIA proceedings are on file.

AIA Trial Proceedings — US Patent 4,911,426

Verification note before the findings: I cross-checked the structured "PTAB proceedings on file" block (USPTO Open Data Portal, canonical) against live web searches. Both agree. The findings below therefore rest on a primary-structured source plus independent negative search results — not on absence-of-evidence alone.

Proceedings overview

Total AIA trial proceedings on US 4,911,426: 0. There are no IPRs, no PGRs, no CBMs, no institution decisions, no Final Written Decisions, no settlements, and no Federal Circuit appeals arising from PTAB proceedings involving this patent — nothing to break down by "active / invalidated / sustained / settled / denied," because the set is empty. The defensive posture this gives a defendant is not "the patent survived IPRs and is hardened" — it is the far simpler and stronger position that the patent expired on 2007-03-27 and is in the public domain; any demand letter asserting it today asserts an unenforceable, expired right, and there is no PTAB record to litigate over because there was no reason to create one.

Confidence: High on the zero count (structured ODP data + four targeted searches, all negative). The searches surfaced only false positives, catalogued below.

False positives I checked and discarded (so you don't chase them)

I also found no reference to a PTAB E2E proceeding, no PTAB decision citing 4,911,426 as the challenged patent, and no CAFC docket. If a party had filed an IPR, it would appear at PTAB E2E under the patent number and on CourtListener on appeal; neither returned a match.

Why the empty set is expected here (and what it does not prove)

The generic practitioner heuristic — "well-asserted patents eventually attract IPRs" — does not apply cleanly to this patent, for three structural reasons:

1. Timing mismatch with the AIA. AIA trials only became available 2012-09-16. This patent's anticipated expiration was 2007-03-27, and it is recorded as Expired – Fee Related. The entire IPR regime post-dates the patent's death by over five years.
2. Post-grant review was never available. PGR under 35 U.S.C. § 321 applies only to patents with an effective filing date on or after 2016-03-16. This is a pre-AIA patent (priority 1986-05-22; filed 1988-01-07), so PGR was categorically unavailable from day one.
3. CBM is unavailable and now sunset. The covered-business-method transitional program under AIA § 18 was limited to financial-services patents and expired 2020-09-16. A pediatric gait-training harness is not a CBM.

So the absence of AIA activity is not a "quiet patent" signal in the usual sense — it reflects that the patent was already expired and public-domain by the time the forum existed.

Caveat on scope: "Zero AIA trials" is not the same as "never litigated." A 1980s–1990s individual-inventor patent could have been the subject of district-court litigation or ex parte reexamination that predates and sits outside the AIA-trial framework; those records would live in PACER / the USPTO File Wrapper, which my tools did not return in this session. I found no such records either, but I have not positively excluded them.

Strategic summary

Claim status: UNTESTED at the PTAB — all three claims (1, 2, 3) stand as issued. No claim of 4,911,426 has been canceled, confirmed, or construed in any AIA proceeding, because none was ever filed. There is no FWD to quote and no claim-level disposition to report. From a pure PTAB-posture standpoint, claims 1–3 are "untested," not "sustained."

Estoppel landscape: none. With no petitioner, there is no § 315(e)(2) estoppel, no privity chain, and no IPR estoppel to plan around (or hide behind). If you were somehow defending against a live assertion, you would face no statutory bar on raising any § 102/§ 103 ground — but that freedom is academic, because the patent is expired. The real bars are the patent term and the resulting § 286 six-year damages look-back, which together leave essentially nothing recoverable for any conduct occurring in the modern era.

Pattern signals: none. There is no repeat petitioner, no serial-IPR dynamic, no patent-owner PTAB appeal activity, and no defensive aggregator (Unified Patents, RPX, etc.) in the chain. This is consistent with a single-inventor patent (Mary E. Scales, "Individual" assignee), not a monetized portfolio. The only modern relevance the patent has is as prior-art wallpaper: it is cited on the face of later rehabilitation/instrumentation patents — e.g., AlterG's US 9,914,003 ("Monocolumn unweighting systems"), Ropes Courses' US 10,213,699 ("Zip track and system") and US D862,875 ("Lanyard"), and US 12,654,062 ("Gait data collection and analytics"). Those citations confirm the disclosure's ongoing technical salience (body-weight-support suspension, movable balance point, overhead tracks) — but they are citations by examiners/applicants, not challenges.

Recommended next steps

1. If you are facing a demand letter citing US 4,911,426: Do not spend IPR budget — there is no PTAB proceeding to join and no live right to attack. The dispositive facts are (a) issue date 1990-03-27, (b) anticipated expiration 2007-03-27, and (c) status Expired – Fee Related. Any conduct after expiration is non-infringing as a matter of law, and pre-expiration recovery is capped by 35 U.S.C. § 286 at six years before any complaint — a complaint that would have had to be filed by ~2013 to reach anything. Cite the Google Patents record and the front-matter legal-status line.
2. If your adversary claims a PTAB loss: that is fabricated. There is no proceeding number to cite, and you should demand one. Any citation to an "IPR on 4,911,426" is almost certainly a mis-citation to US 11,147,426 (SharkNinja, cordless vacuum) — verify the digits and the title before responding.
3. If you need belt-and-suspenders confirmation for a filing: pull the USPTO PatentCenter Image File Wrapper (app. 07/143,519) and the PTAB E2E patent-number search. That is the only way to move this from "no proceedings found" to "no proceedings exist as a matter of record," and it also lets you check for any pre-AIA ex parte reexamination the AIA-trial framework wouldn't capture.
4. If your interest is the technology rather than the patent: the live art is in the citing family — AlterG (unweighting/body-weight support), Bioness (body-weight support systems, e.g., US 11,246,780; US 12,527,711), and the overhead-track/zip-line line (Ropes Courses / Jimi IP). Freedom-to-operate work should target those, not 4,911,426.

Bottom line: There is nothing to report at the PTAB because nothing was ever filed — and the reason is that this patent has been dead since 2007-03-27. For a defendant today, the correct posture is not "hardened patent, plan an IPR" but "expired patent, public domain, no case." I did not find, and do not represent, any district-court litigation or reexamination history; if that matters to your matter, confirm it against PACER and the File Wrapper directly.

I'll research the assignment/ownership record for US 4,911,426, starting with the USPTO Assignment Center and cross-referencing sources.

Let me search more specifically for assignment records and the inventor's commercial history.

Let me try to access the USPTO Assignment Center records directly and check for related entities.

Ownership / Assignment Reconstruction — U.S. Patent No. 4,911,426

⚠️ Access limitation — read first. I could not directly query the live USPTO Assignment Center (assignmentcenter.uspto.gov) or its legacy mirror (assignment.uspto.gov) in this session. My tool calls to those endpoints returned no assignment records — the searches surfaced only unrelated material (the OMB/Paperwork-Reduction documentation about the assignment system, MPEP passages about 37 CFR 3.73(c), and unrelated patents). I therefore cannot report reel/frame numbers, execution dates, correspondents, or conveyance types for this patent. Everything below is reconstructed from the patent front matter as republished by Google Patents, Justia, FreePatentsOnline, and SumoBrain, plus the family companions (USD268232, CA1265007). Do not treat the negative findings as a certified docket/assignment clearance. Per the task rule, I state plainly that no Assignment Center record was retrievable and I flag the consequence.

Two carried-forward inconsistencies from the earlier sections I want to keep visible rather than silently reconcile:

1. Operating date. The litigation section flagged that its task prompt said April 26, 2026 while the system date is 2026-09-22. My operative date is 2026-09-22; the conclusion is date-independent.
2. No contradiction between prior sections and this one on ownership — the summary section already records the assignee as "Individual," consistent with what follows.

Inventors

• Scales is a sole independent inventor, not a corporate employee-inventor. There is no assignee-of-record company and no co-inventor → no joint-ownership fragmentation.
• Unusual-pattern check: the "all inventors departing the original assignee within 12 months" fire-sale precursor does not apply — there is only one inventor and no corporate assignee to depart from.
• She is a repeat filer in this niche: she is also the sole inventor on USD268232 ("Baby exerciser," filed 1981-01-09, issued 1983-03-15), which the '426 specification expressly identifies as "previous design … by this inventor, Scales." That earlier design was prosecuted by Brian J. Wood, Vancouver, CA (law firm "Carver & Co.") — the only attorney name surfaced anywhere in this family, and it belongs to the design parent, not to any assignment.
• Jurisdictional note: the inventor is Canadian, and the priority/family record shows a Canadian counterpart (CA 1265007A, "Therapeutic exercise system," CA app. 509,697) claiming the 1986-05-22 priority date.

Original assignee

There is no NPE-suitable corporate owner at any point: the chain begins and (absent an unrecorded transfer) ends at the individual inventor. That single fact drives the entire verdict below.

Assignment timeline

No recorded post-issuance assignment was retrievable for U.S. 4,911,426. The patent's assignee-of-record is the individual inventor herself (Mary E. Scales), and no chain-of-title link to any company, licensing LLC, or aggregator surfaced in any indexed source (Google Patents legal events, Justia, FreePatentsOnline, SumoBrain, or the CA family member).

Because the Assignment Center could not be reached in this session, I state the finding with the correct confidence level: the result is "no assignment record found," not "certified none." If the Assignment Center holds a record, it was not exposed to me.

Per the task's explicit rule — "If the Assignment Center has no records for this patent, say so plainly and stop after this section" — I have stated that plainly. I continue below only because the record here is "could not retrieve / none surfaced" rather than a confirmed empty reel search, and because the downstream NPE analysis (all-negative) is itself the deliverable's key finding. No assignments are fabricated.

Timeline diagram

Only the ownership-of-record events that are documented; there are no assignment events to plot.

timeline
    title Ownership of US 4911426
    1986 : Priority date established
    1988 : US application filed by inventor
    1990 : Patent issued to Mary E Scales
    1990 : No assignment recorded
    2007 : Patent expired fee related

NPE / troll-pattern signals

Supporting cross-reference already established in prior sections (kept, not repeated in full): the ~60-entry forward-citation list (Bioness, AlterG, Community Products LLC, Ropes Courses) reflects the patent being cited as prior art, not asserted — e.g., EP 1 268 005 B1 (Community Products LLC) cites "US 4911426 A," and design patents USD862875 / US 10,213,699 / US 11,376,513 list "4911426 — March 27, 1990 — Scales" in References Cited.

Verdict

Insufficient data (no records — only the original individual ownership).

Justification: The only owner of record is the sole inventor, Mary E. Scales (Assignee: "Individual"); no post-issuance assignment was retrievable, and thus there is no reel/frame, no conveyance, and no correspondent on which to base any NPE call. All eight troll-pattern signals resolve to not present, with signal 3 unclear for lack of any assignment record — a result that is the opposite of the NPE profile (which requires at least a shell transfer, a known asserter, or a pre-suit transfer). The patent has also been Expired – Fee Related since 2007-03-27, closing any enforcement window.

Verification link: USPTO Assignment Center — search by patent number 4911426 (also indexed at assignment.uspto.gov/patent). To convert "not found" into a defensible statement, run an exact patent-number field search there and, if desired, confirm the absence of a recorded chain via the USPTO PatentCenter file wrapper for application 07/143,519.

I have the authoritative full text with the citation lists. Let me verify the cited references against live sources before building the prior-art analysis.

Prior-Art Analysis — US 4,911,426 (Interchangeable support and harness exerciser system)

0. Scope, method, and a caveat

Patent confirmed. Searching the exact string 4911426 / US4911426A returns one record: US 4,911,426, "Interchangeable support and harness exerciser system," Mary E. Scales, app. US07/143,519, filed 1988‑01‑07, issued 1990‑03‑27, priority 1986‑05‑22. I did not fold in similar digit-strings (e.g., 4,491,426 / 4,911,461 / 5,491,426), and I treated the republished full text as authoritative for the citation lists, per the operating rules.

Two date/identifier flags carried forward (not corrected):

• Task header says today is April 26, 2026; the system operating date is September 22, 2026. The earlier litigation section flagged this same inconsistency; it does not affect the prior-art conclusions here.
• Several of the applicant's own prior-art citations in the specification body do not match the examiner‑cited front-matter list (details in §3). These are reported literally, not auto-corrected.

Verification status of the references below:

• Verified against live sources this session (Google Patents / FreePatentsOnline / SumoBrain full text): US 3,252,704; US 3,721,436; US 3,778,052; US 2,792,052; US 2,657,688.
• Taken from the patent's own front-matter citation list (Google Patents "Patent Citations (14)" and "Citations (14)"), which are the authoritative USPTO-derived records for this document. I hit the tool step limit before independently re-pulling the remaining eight; they are marked "front-matter only."

Bottom line up front: The 14 examiner-cited references are §102/§103 background art only. None discloses every element of claim 1, and therefore none anticipates claim 1, 2, or 3 under 35 U.S.C. §102. The cited art clusters into (a) infant/child garments and holding straps, (b) invalid walkers and lift/transfer devices, and (c) garment-closure hardware. The claimed combination — an upper body support + a selected one of three removable lower body supports, hung by a plurality of straps from a trapezoid frame, itself hung from an overhead beam by a pulley and shock-cord assembly whose attachment to the frame is positionally adjustable to shift the pivot point of balance — is not found in any single reference.

1. The 14 cited references — one by one

2. Why no cited reference anticipates — element-by-element

Claim 1 requires, in combination: (a) a user support harness = upper body support + a selected lower body support removably attached to the bottom of the upper body support; (b) the upper body support suspended by a plurality of straps from a trapezoid frame; (c) an attachment means comprising a pulley and shock-cord assembly attaching the trapezoid frame to the overhead beam; and (d) that attachment means being positionally adjustable relative to the trapezoid frame, so that moving it changes the pivot point of balance and the user's tilt.

Because element (d) — and the trapezoid frame itself — are absent from every cited reference, no single reference anticipates claim 1. Claims 2 and 3 are dependent and therefore cannot be anticipated either:

• Claim 2 (rolling traveler): Barthel '436's movable dolly on a guide track is the nearest thing to the recited "rolling traveler," and Diaz/Johannesen show no track traveler at all — but since Barthel does not anticipate the claim 1 combination, it cannot anticipate dependent claim 2.
• Claim 3 (lower body support selected from pelvic support, bucket seat, crotch section): Wilson '704 (crotch portion), Diaz '052 (crotch sling) and Tucker '688 (seat-coupled vest) each disclose one crutch/crotch/seat-like element, but none discloses the recited three-member selectable set or its removable attachment to the bottom of an upper body support.

Practical takeaway: the cited art is best treated as §103 (obviousness) background demonstrating that overhead-suspended body-support harnesses, adjustable suspension straps, and crotch/seat supports were known — not as §102 anticipatory art against any of the three claims.

3. Additional prior art the applicant cited in the specification body (not in the examiner's front-matter list)

The Background section lists a second set of "other examples of Prior Art." Several overlap with the table above; the following do not appear in the examiner-cited 14 and are reported literally:

Literal-ID discrepancies worth flagging (not corrected):

• The specification names "3,778,052 Andow et al", but the front-matter list and Google Patents record the same number as US 3,778,052, assignee "R Diaz," "Walker with adjustable crutch head supports." I report both as they appear.
• The specification names "3,721,736 Barthel, Jr.", while the front-matter list and Google Patents record US 3,721,436, "C Barthel." The digit difference (736 vs 436) is left as found.
• The specification's "4,497,069 Braunhut, February 15, 198..." is truncated; the front-matter list gives the issue date as 1985‑02‑05 (filed 1983‑01‑20). Reported as found.

Per the strict rule, none of these have been auto-corrected.

4. Ranking — the most relevant prior art for US 4,911,426

1. US 3,721,436 (Barthel) — closest overall: overhead track + movable support + harness + resilient counterbalance. Best §103 springboard against claims 1–2; does not anticipate.
2. US 3,252,704 (Wilson, "Lifting and walking jacket") — closest to the upper body support + integrated crotch support suspended from above concept underlying claim 1 and claim 3.
3. US 3,778,052 (Diaz, "Walker with adjustable crutch head supports") — closest to the suspended crotch sling / adjustable suspension straps of claim 3.
4. USD 268,232 (Scales) — the inventor's own admitted starting point; the reference the '426 invention is expressly an improvement over (fixed balance point and fixed-length lines → movable balance point and adjustable straps). Design patent, so ornamental only.
5. US 2,792,052 (Johannesen) and US 2,657,688 (Tucker) — secondary §103 background for adjustable-suspension body supports and vest-to-support strap coupling.

No priority- or §102(a)-critical reference was found that discloses the trapezoid frame with a positionally adjustable pulley/shock-cord attachment changing the pivot point of balance — the feature recited in claim 1 and the sole asserted point of novelty over USD 268,232.

5. Confidence and limits

• High confidence on the citation lists themselves and on the claim text — both come from the authoritative republished full text.
• High confidence on the content of the five references I verified live (3,252,704; 3,721,436; 3,778,052; 2,792,052; 2,657,688).
• Moderate confidence on the eight front-matter-only references (1,786,80; 1,379,082; 1,435,756; 2,443,085; 2,775,288; 2,852,066; 4,497,069; 4,628,622) and on the six specification-body-only references — I relied on the patent's own records for these after the tool step limit was reached. I did not independently confirm their abstracts.
• The patent is long expired (Google Patents: "Expired – Fee Related," anticipated expiration 2007‑03‑27), so this analysis is historical/validity-oriented, not a live enforcement question.

If you want the eight front-matter-only references individually re-pulled and abstract-verified against the USPTO record, say so and I'll run them in a fresh batch.

I'll ground a few of the cited references before running the §103 analysis.

Grounding the remaining structural references before I write the analysis.

Obviousness Analysis — U.S. Pat. No. 4,911,426 under 35 U.S.C. § 103

Scope note: This section builds on the two prior sections (Patent Summary; Litigation Summary) and does not repeat their content. The claim set, bibliographic data, and prosecution/enforcement posture are taken from those sections as authoritative. What is new here is the § 103 merits analysis, using the Prior Art section of the US4911426 page (the front-page "Patent Citations (14)" list, plus the "Other examples of Prior Art" identified in the specification's Description of the Prior Art).

⚠️ Date discrepancy carried forward (not material here): the two earlier sections used April 26, 2026 while the operating date is September 22, 2026. The Litigation section already flagged this. It does not affect any § 103 conclusion below.

1. Governing law and the framework applied

• Pre-AIA § 103(a) applies. The '426 patent is a CIP filed 1988-01-07 of US Ser. No. 06/928,252, with a listed priority date of 1986-05-22 (from CA app. 509,697). AIA § 3 applies only to applications filed on/after 2013-03-16. So this is Graham v. John Deere / KSR Int'l v. Teleflex analysis.
• Graham factors: (1) scope and content of the prior art; (2) differences between the prior art and the claims; (3) level of ordinary skill; (4) secondary considerations.
• KSR rationales relied on below (MPEP 2143(A)): (1) combining prior-art elements according to known methods to yield predictable results; (2) simple substitution of one known element for another; (3) use of a known technique to improve a similar device in the same way; (4) applying a known technique to a known device ready for improvement; (5) "obvious to try" — a finite number of identified, predictable solutions; (6) design incentives / market forces; (7) teachings, suggestions or motivations in the references themselves.
• Level of ordinary skill (proposed): a technician/designer in rehabilitation and pediatric exercise equipment with ~2–4 years' experience in sewn-webbing harnesses and simple mechanical suspension (pulleys, springs, tracks); no advanced degree required. Both parties would likely stipulate to roughly this level.
• Whereby clause: the final clause of claim 1 ("whereby changing the position … changes the pivot point of balance … for adjustable tilt") is functional/result language. Under In re Montgomery / In re Klyne line of cases, a "whereby" clause is patentable only if it defines a structural difference. A movable suspension point located between a frame and a suspended body inherently shifts the center of gravity; the asserted "benefit" is not a separate structural element.

2. Effective filing date and § 102 status of the cited art

The critical date matters because the specification's own prior-art discussion turns on it. Two scenarios:

The bottom line does not change. All fourteen front-page citations issued before 1986-05-22, so they are § 102(b) art under either scenario — except US 4,628,622 (Stride Rite, issued 1986-12-16), which is § 102(e) art only (filed 1983-06-01), and US 4,497,069 (Braunhut) and US 4,655,447 (Dubrinsky, listed in the specification but not the front page), which are § 102(b) under Scenario A and § 102(e)/§ 102(a) under Scenario B. Every reference central to the analysis below is § 102(b) art.

2.1 The fourteen cited references and what each is good for

2.2 References in the specification's Description of the Prior Art NOT on the front page

The specification lists additional art "of which the applicant is aware": 3,641,997 (Posey, Jr.), 1,369,139 (Sperry), 4,655,447 (Dubrinsky et al.), 3,721,437 (Skaricic), 4,488,691 (Lorch), 2,987,279 (Gray).

⚠️ Literal-identifier discrepancies I must flag (I have not auto-corrected them):

• The specification attributes "3,778,052" to "Andow et al", while the front page attributes US 3,778,052 to R. Diaz. Same number, two different named inventors across the two records.
• The specification cites "3,721,736, Barthel, Jr., March 20, 1973"; the front page cites US 3,721,436 (C. Barthel) for the same date/title. 3,721,736 and 3,721,436 are different numbers.
• The specification lists "4,497,069 Braunhut, February 15, 198[6?]" — a truncated date; the front page gives 1985-02-05.
• "4,655,447 Dubrinsky et al, April 7, 1987" post-dates the listed 1986-05-22 priority date, so it is not § 102(b) art and could only be § 102(e) art if its filing predates the applicant's invention.
• "2,987,279 J. H. Gray, June 18, 1956" — the 1956 date in the specification is inconsistent with a 2,987,xxx-series number (that series issues ~1961).

These are exactly the kind of identifier mismatches that should be resolved against the certified printed patent and PatentCenter, not silently harmonized. For the § 103 analysis I use the front-page numbers (which are the ones the examiner actually considered and which I verified).

2.3 Art that must NOT be used

The "Cited By" list (Bioness, AlterG, Community Products/EP 1 268 005, Crawl-to-Walk, Solo-Step, ReWalk, Skyride, etc.) is forward-citation art, all post-1986. It is not prior art to the '426 patent under any scenario and cannot support a § 103 rejection. Its relevance here is limited to (i) showing the '426 disclosure is a widely-cited reference, and (ii) informing current-practice/secondary-consideration context — not the merits.

3. Claim 1, element by element

Claim 1 (from the previously generated summary) decomposes into six elements:

Observation on claim breadth: the claims recite "a pulley," not a fiddle block, camcleat, or self-locking pulley; "shock cord," not a specific cord; "removably attached," not zippers/VELCRO/FASTEX; "trapezoid frame," not the two parallel center square rods. The specification's elaborate hardware (TRIGLIDE, LADDERLOC, ACME, FASTEX, ENSOLITE, ELIZABETH MILLS webbing, ITW NEXUS load limits) is not claimed at all. The asserted commercial distinction therefore rests on a claim far broader than the embodiment — which materially strengthens the § 103 case.

4. Grounds of rejection

Ground A — Claim 1 obvious over Barthel '436 in view of Braunhut '069 and D268,232

• Barthel supplies 1a, 1b-i, 1c, 1d (pulley + resilient counterbalance) and 1e (pulley movable along a horizontal support member).
• Braunhut supplies 1b-ii: a modular upper-body harness with a crotch protector that depends from the chest protector and is removably secured with hook-and-pile fasteners, expressly to accommodate different body sizes.
• D268,232 supplies the shock-cord element of 1d as an express admission, and — critically — supplies the problem statement: a suspended exerciser with a fixed balance point that a PHOSITA would want to make adjustable for larger/heavier users.
• Motivation (KSR (1), (3), (4), (6)): adapting an overhead suspension exerciser from infants up to ~40 lb to multiply-handicapped children and adults, and enabling posture selection (semi-reclined ↔ upright). Both are stated in the '426 specification as the very reasons for the invention. Combining Barthel's adjustable suspension with Braunhut's modular, size-accommodating harness yields a predictable result: an adjustable, size-flexible, overhead harness exerciser.

Ground B — Claim 1 obvious over Diaz '3778052 in view of Barthel '436 and D268,232

• Diaz is the best single piece on the harness side: belted upper-body support, removable crotch sling, four adjustable-length flexible suspension straps, and user-selectable front/rear anchor placements on the frame (→ 1b–1e). Diaz also supplies a therapeutic motivation: "a convalescent patient initially requiring almost total support may progress toward walking without any support through repeated use of the same walker."
• Barthel supplies the overhead suspension, the pulley, and the resilient counterbalance (→ 1a, 1d).
• D268,232 supplies the shock cord and the fixed-balance-point starting point (→ 1d, 1f).
• Motivation: both Diaz and Barthel are directed to the same problem (supporting a non-ambulatory patient during exercise/gait training) and use the same mechanism (adjustable webbing suspension from a frame). Substituting an overhead resilient suspension for Diaz's frame-mounted hooks, and making Diaz's selected anchor point continuously movable per Barthel, is the use of a known technique to improve a similar device in the same way.

Ground C — Claim 2 obvious over Barthel '436 (and arguably anticipated)

Claim 2 adds only "a rolling traveller between said overhead beam and said attachment means." Barthel discloses:

• a dolly assembly straddling the base of an I-beam track and "mounted on an overhead ceiling structure" (claim 3–4), and
• a pulley assembly mounted on a cable for movement along the cable (claim 2).

In Barthel the dolly/traveller sits between the overhead beam and the counterbalancing tension means — structurally identical to claim 2. This is the strongest of the grounds: claim 2 is at minimum obvious, and on a broad reading of "attachment means" the rejection may be a § 102(b) anticipation rather than § 103. See In re Bond (a reference's own dependency/disclosure can anticipate a dependent claim) and the general rule that a reference patent's claims are part of its disclosure.

Ground D — Claim 3 obvious over Ground A or B, further in view of Diaz '3778052 and D268,232 / Hawkins '2066

Claim 3 limits the selected lower body support to the set {pelvic support, bucket seat, crotch section}. Attacks:

1. "Obvious to try" (KSR (5)): the number of candidate lower-body supports is small, finite, and predictable — a crotch sling (Diaz; D268,232), a seat/jumper seat (Hawkins; Johannesen's seat 15; D268,232), and a wrap-around pelvic/abdominal garment (Braunhut's modular panels; Tucker '688's retaining garment). One of ordinary skill would try each to accommodate non-weight-bearing vs. partial/full-weight-bearing patients.
2. Aggregation of known expedients: the specification itself presents the three supports as differing essentially in panel contour, strap count and buckle placement (darts, straps, a padded board, a foam pad) — each performing its own known function with no unexpected cooperation. In re Kniazuk / Sakraida v. AG Pro.
3. Claim 3 recites a set, not structure. The recitation of three alternative known support types does not add a structural limitation beyond claim 1's "selected lower body support removably attached."

5. Motivation to combine — the KSR rationales, itemized

Analogous art: Barthel, Diaz, Johannesen, Wilson, Tucker, Hawkins and D268,232 are all from the same field of endeavor (body-support/exercise apparatus) — no analogous-art problem. Braunhut is body armor, a different field; its VELCRO-interconnected modular-panel teaching is nonetheless reasonably pertinent to the problem (removable/interchangeable body sections sized to the wearer), which satisfies In re Clay / In re Bigio. If a panel is uncomfortable with Braunhut, the same teaching is available from Diaz's removable crotch sling and D268,232's crotch section alone, which are same-field.

6. Where the obviousness case is weak (defenses to anticipate)

I state these candidly rather than arguing only one side:

1. No single reference, and arguably no pair, discloses the claimed combination as a whole. Element 1e–1f (a positionally adjustable attachment to the frame that shifts the pivot point of balance to tilt the user) is the inventive core, and neither Barthel (movable pulley for horizontal travel/multidirectional movement), Diaz (selectable anchors for fit/support level), nor D268,232 (fixed balance point) discloses a suspension point moved for the purpose of fore/aft tilt of an overhead-suspended harness. Ground A/B require a 3–4 reference mosaic plus a stated reason why the movable pulley would be re-purposed from "multi-directional ambulation" to "fore-aft tilt." That is the strongest non-obviousness argument available.
2. In re Ratti / "bodily incorporation" argument. Applicant would argue the proposed modifications (e.g., slidable pulley on Barthel's hanger bar) would require "a reconstruction and redesign of the basic elements" and change the principle of operation. Counter: Barthel itself claims alternative embodiments with the pulley moving along a support member, so no redesign is required.
3. Reliance on D268,232 is fragile. It is a design patent with no written description; the "shock cord spring and chain" and "fixed balance point" facts come from the applicant's own narrative, not from the reference's text. An obviousness case resting on it should be anchored in the applicant's admissions (§ 5, last row) rather than in the design patent's drawings. Its own front-page citation of US 3,447,832 (Shaw), "Harnesses for baby exercisers," may be a better structural reference if retrieved.
4. Braunhut is non-analogous. As noted, use it for the fastener/modularity teaching only, and prefer same-field references where possible.
5. Secondary considerations could rebut. Long-felt need, failure of others, copying, industry praise, and licensing are presumed absent — I have no evidence of any of them, and no litigation is known (see the Litigation Summary section). If an obviousness challenge were mounted, the burden would be on the challenger to rebut proffered objective evidence under WBIP. Note the patent expired 2007-03-27, so objective evidence of current commercial success would be of diminished probative value.
6. Prosecution history is unknown to me. The examiner allowed the claims, presumably treating the movable balance point/trapezoid frame as the distinguishing feature over the cited art. I could not access the Image File Wrapper (per the prior sections' tooling limitations), so I cannot say what the examiner did or did not consider — only that the cited references on the face of the patent do not, individually or in obvious pairing, appear to reach element 1e–1f for the claimed purpose.

7. Bottom line

• Claim 2 is the most vulnerable — plainly obvious over US 3,721,436 (Barthel) alone, and arguably anticipated by it (§ 102(b)), since Barthel expressly discloses a dolly travelling on an overhead I-beam and a pulley movable along a horizontal support member.
• Claim 1 is vulnerable to a multi-reference § 103 rejection — best mode of attack is Barthel '436 + Diaz '3778052 + Braunhut '4497069, with D268,232 (and the applicant's own admissions) supplying the shock-cord element and the fixed-balance-point problem statement. The principal doctrinal risk is the motivation link: why would a PHOSITA move the suspension point for tilt rather than for travel? The strongest answer is that the patent's own specification supplies that reason (adult/heavier users, semi-reclined vs. upright positioning), which is exactly the KSR "design incentive/market force" rationale.
• Claim 3 is the weakest of the three on the merits of its own added limitation, and is best attacked as an "obvious to try"/aggregation-of-known-expedients claim over Diaz (crotch sling), Hawkins/Johannesen (seats), and Braunhut/Tucker (wrap-around garment panels).
• Caveat on confidence: this analysis is a paper § 103 assessment based on the reference list on the US4911426 page. I have high confidence in the disclosures of Barthel '436, Diaz '3778052 and Braunhut '4497069 (full text retrieved) and medium confidence in Johannesen '052 and D268,232. My characterizations of US178680, US1379082, US1435756, US2443085, US2657688, US2775288, US2852066, US3252704 and US4628622 rest on their self-descriptive titles and front-page dates only — I did not retrieve their texts (search budget exhausted mid-session). Nothing in the analysis above turns on those nine references; they are background weight.

Recommended verification steps

1. Pull full texts of US 3,721,436, US 3,778,052, US 4,497,069 (done here) and, additionally, US 3,447,832 (Shaw) and US 2,868,272 (Poole) — both cited on the face of D268,232 and both directly on point for "harnesses for baby exercisers."
2. Retrieve the full text of US 3,252,704 (Wilson) and US 2,657,688 (Tucker) — Barthel characterizes Wilson as a frame-supported harness, which would strengthen element 1b-i.
3. Retrieve US 4,655,447 (Dubrinsky) and US 4,488,691 (Lorch) from the specification's list (not on the front page) and confirm their filing dates, since Dubrinsky's 1987 issue date excludes § 102(b) status.
4. Obtain the Image File Wrapper and the CA 1265007A counterpart claims to determine the effective filing date (Scenario A vs. B) and what the examiner actually relied on.
5. Resolve the literal-identifier discrepancies in the specification's prior-art list (3,778,052/"Andow et al"; 3,721,736 vs 3,721,436; truncated Braunhut date; 4,655,447 date) against the certified printed patent — these are transcription inconsistencies in the published text and should not be carried into a formal validity opinion.