US 4771840

I'll search for authoritative information on US patent 4771840, including any CAFC 2026 activity.

Let me run additional targeted checks for any litigation or CAFC activity involving this specific patent number.

US Patent 4,771,840 — Summary

Important threshold note on scope: I ran targeted searches of USPTO-facing sources (Google Patents, USPTO.report, EPO citation records) and broader web searches for any CAFC 2026 docket referencing this patent number. I found no evidence of any Federal Circuit litigation, appeal, IPR, or 2026 docket activity involving U.S. 4,771,840. The patent lapsed decades ago (see status below), so this is consistent with there being no live appellate matter. If a specific CAFC 2026 docket number was expected, I do not have authoritative confirmation of one — treat the "no litigation found" conclusion as a search-based finding, not a definitive negative.

Bibliographic Data (from the patent record)

Abstract (as issued)

"An articulated shopping cart-tractor unit with a seat is provided for the handicapped. The tractor unit is connected to a conventional shopping cart by a bracket and coupling."

Prior art cited on the face (9 references, incl. examiner citations)

US 2,354,576 (Clark); US 2,867,449 (Shawver); US 3,190,386 (Swinny); US 3,524,512 (Voeks); US 3,575,250 (Dykes); US 4,020,916 (Noble); US 4,570,739 (Kramer/Burke); US 4,633,962 (Cox). The specification specifically distinguishes the '512 and '916 patents (both provide a seat and electric propulsion) on the ground that they lack a sufficiently small turning radius.

Plain-Language Overview of the Independent Claims

There are five claims total; two are independent (claims 1 and 5). Claims 2–4 depend on the chain 1→2→3→4.

Claim 1 (independent) — the core articulated cart+tractor combination:
A combination of (a) a shopping cart with handle portions and front and rear wheel casters, and (b) a powered tractor unit with its own frame, wheels, and power means driving at least one tractor wheel. The two are joined by coupling means consisting of a ball-joint male member attached to the cart frame near the rear casters and a ball-socket female member mounted on the tractor frame, engaged to give "unhindered yaw, pitch and roll" between cart and tractor. The coupling defines a pivot axis; the tractor wheels define a power axis. Critically, the distance between the pivot axis and the power axis is dimensioned to give a turning radius adequate to make a continuous U-turn from one supermarket aisle to an adjacent aisle. (The spec teaches ~26 inches for this distance, sized to typical 8–10 ft aisle centerlines.)

Claim 5 (independent) — the same combination, focused on the mounting bracket:
A shopping cart (with basket; frame with handle portions, front wheel casters, horizontal caster-supporting runs, and upwardly extending frame runs supporting the basket) plus a powered tractor unit with frame, wheels and power means. The coupling means provides yaw/pitch/roll and defines a pivot axis, and specifically includes a generally U-shaped bracket whose leg portions fit within the shopping cart frame, with clamping members fixed to the leg portions and clamped by U-bolts to the horizontal and upwardly extending frame runs. In other words, this claim is directed to the removable, no-modification clamp-on hitch structure that lets the tractor attach to an existing cart.

Dependent Claims (brief, for completeness)

• Claim 2 adds bumpers on each side of the tractor frame that coact with cart frame portions to limit turning yaw (prevent jackknifing) while still permitting enough angular displacement for the optimum turning radius. (Spec: ±30°.)
• Claim 3 adds a foot platform and a seat positioned so the occupant's center of gravity is forward of the power axis, loading the coupling downward to minimize pitch.
• Claim 4 adds that the seat is pivotally mounted, allowing the occupant to stand (to reach shelves) but limiting seat rotation so the center of gravity cannot shift rearward of the pivot axis.

Caveats / Uncertainty

• Bibliographic facts above are drawn from the authoritative patent text provided and corroborated by uspto.report and Google Patents; these agree.
• The "no CAFC 2026 docket" finding reflects the searches I could run and is not a guarantee that no unrelated court filing exists that simply does not mention the number in indexable text. I did not locate any assignment beyond the original ORTHOKINETICS record, and the patent's 1996 lapse means it could not be asserted today.
• Litigation databases available to me did not return any case caption tying this patent number to a Federal Circuit appeal in 2026.

I'll run targeted searches on litigation-focused sources for this specific patent number.

Initial searches returned no litigation. Let me check litigation-specific databases.

I've reached my search limits. Here is my finding.

Litigation Search — U.S. Patent No. 4,771,840

Bottom line

No litigation involving U.S. Patent No. 4,771,840 was found. I searched litigation-oriented sources for this specific patent number, and no district court case, Federal Circuit appeal, ITC Section 337 investigation, or PTAB proceeding (IPR/PGR/CBM) naming this patent as an asserted or challenged patent was returned.

What I searched and what came back

I was unable to directly query the Unified Patents litigation portal, Docket Navigator, RPX, or PACER case-search for this number before exhausting my search steps, so this is a search-based negative, not a certified negative.

Why "no litigation" is the expected and highly probable answer

The prosecution history and status record in the authoritative patent text explain why no enforcement action exists:

• The patent is long dead. It lapsed for failure to pay maintenance fees, with the lapse effective 1996-09-25 (REM/ LAPS/FP entries). A later entry dated 2018-01-30 confirms expiration for nonpayment under 37 CFR 1.362. The anticipated expiration is recorded as 2007-04-15.
• Damages window closed. Under 35 U.S.C. § 286, a plaintiff may recover only for infringement occurring within six years before suit; with the patent lapsed in 1996 and expired in 2007, there is no live right to assert today, and a suit would be time-barred and moot.
• No recorded transfers. The only assignment on record is the original inventor-to-assignee assignment (Keller → ORTHOKINETICS, Waukesha, WI), recorded 1987-04-15. There is no evidence of the patent ever passing to an NPE or other asserting entity, which is the usual precondition for the modern litigation pattern (see the many later cart-mover/hospital-bed-mover cases in the "Cited By" list — Dane Industries, Hill-Rom, Gatekeeper, etc. — none of which asserted this patent).

Case table (as requested)

Caveats and confidence

• Confidence: high that no litigation was ever filed asserting the '840 patent, based on (a) the absence of any litigation reference in the Google Patents record itself (which typically carries an "Also Published As / Litigation" linkage and 96+ citing documents but no case history), and (b) the patent's 1996 lapse.
• Not a certified negative. I could not run final confirming queries against PACER's full docket index, Unified Patents' litigation case list, or Docket Navigator for the exact number. Pre-1990s patent suits are also less completely digitized in free databases, so a very old (1988–1996) suit could theoretically exist outside the indexable record. However, no such suit is reflected in any surface of the authoritative record provided.
• Unrelated "4771840" hits to disregard: the CourtListener financial-disclosure entry (ID 4771840 = an investment line item) and the Brazilian JUCEPAR/JUCISRS notary PDF are coincidental number matches, not patent litigation.
• Contradiction flag: none between the previously generated summary and this analysis — the prior section's conclusion (no CAFC 2026 activity; patent lapsed 1996) is consistent with everything found here.

I'll verify the structured block's finding with targeted searches before finalizing.

Let me run one more targeted confirmation against PTAB-specific surfaces.

Proceedings overview

There are zero AIA trial proceedings on file for US 4,771,840 — no IPRs, no PGRs, no CBMs, none active, none settled, none instituted, none denied — which means the defensive posture is not the "hardened patent" scenario and not the "claims canceled" scenario either: the claims (1–5) were never tested at the PTAB and were never canceled, because the patent lapsed for nonpayment of maintenance fees effective 1996-09-25 and had already been dead for ~16 years when the AIA trial regime began on 2012-09-16. Any demand letter citing claims 1–5 today fails for a simpler reason than invalidity: there is no enforceable patent left to infringe.

This is a search-confirmed negative consistent with the canonical structured block ("USPTO ODP API returns no AIA trial proceedings for this patent as of the most recent ingest") and with the earlier litigation section of this analysis, which likewise found no assertion history.

Proceedings (none to enumerate)

Because the proceeding list is empty, the requested per-proceeding fields (Type / Filed / Status / Judge panel / Grounds / Institution / FWD / Settlement / Appeal / Defensive value) have no entries. Rather than fabricate case numbers — which the task expressly forbids — I set out below the why and the evidentiary basis.

No proceeding exists — the supporting record

• AIA trials were unavailable for most of this patent's life. IPR/PGR/CBM came into force 2012-09-16 (Leahy–Smith America Invents Act). The '840 patent lapsed 1996-09-25, so the entire 2012-onward window postdates its death.
• PGR was categorically unavailable. PGR applies only to patents issued under first-inventor-to-file (post-AIA) practice. The '840 patent filed 1987-04-15 and issued 1988-09-20 — squarely pre-AIA. See USPTO PTAB inventor-hour primer, "Types of AIA Proceedings" (PGR: "Patent issued under first-inventor-to-file"). uspto.gov
• CBM was categorically unavailable. CBM requires a claim to a "financial product or service" and expressly excludes "technological inventions." A mechanical shopping-cart tractor unit (B62B 5/0026; Y10S 280/04) cannot be a covered business method patent. The CBM transitional program also sunset 2020-09-16.
• IPR was legally available but economically irrational. IPR can be filed against expired patents, but there is no exclusionary right to defeat and no infringement defendant to fund the petition. No rational petitioner pays § 42.15 fees for that.
• No reexamination substitute either. The authoritative record shows no ex parte or inter partes reexamination certificate for US 4,771,840 (contrast, e.g., the IPR certificate format seen in US 10,322,315 K1). Nothing post-grant has ever touched these claims.

Independent check for a "no-PTAB" signal

The absence here is not the classic "well-asserted patent that somehow escaped IPR" signal. The usual inference — that a commercially significant, asserted patent will eventually attract a validity challenge — does not apply, because:

1. The patent was never litigated (per the litigation section of this analysis, no district court, ITC, or CAFC matter names this number);
2. The only assignment on record is the original inventor-to-assignee transfer (Keller → ORTHOKINETICS, Waukesha, WI, recorded 1987-04-15) — no NPE or aggregator ever held it; and
3. The right terminated in 1996 for a missed maintenance fee, then was formally recorded as expired under 37 CFR 1.362 (entry dated 2018-01-30).

Strategic summary

Claim status: all five claims UNTESTED, not canceled, and unenforceable by lapse. No FWD, no IPR certificate, no reexamination certificate exists. Claims 1 and 5 (the two independents — ball-joint articulated coupling with pivot-axis/power-axis spacing per claim 1; U-bolt clamp-on bracket per claim 5) and claims 2–4 (bumpers; center-of-gravity-forward seating; limited-rotation pivoting seat) all stand unadjudicated. For a defendant this cuts in your favor but for a different reason than an IPR win: you cannot point to a canceling FWD, but you also don't need one. The 1996 lapse terminated the exclusionary right, so there is no § 271 infringement to plead and no § 284 damages period to reach — 35 U.S.C. § 286's six-year lookback cannot save a complaint filed in 2026 against a patent that died in 1996.

Estoppel landscape: none, and none needed. Section 315(e)(2) estoppel only attaches to a petitioner that reached an FWD — and there is no petitioner. There is therefore no prior-art ground "consumed" by anyone, and no defensive-aggregator chain (no Unified Patents, no RPX, no IPR-funded petitioner of any kind). Practically, if you ever found yourself in a dispute over the '840 family, you would be free to raise § 102/§ 103/§ 112 and equitable defenses with no estoppel tether, and any plaintiff would face a laches/§ 286/time-bar wall plus the fundamental "no live right" defect.

Pattern signals: absent, consistent with a dead, never-asserted patent. No serial filings (there are none at all). No patent-owner appeals because there is nothing to appeal — no institution decision, no FWD, no Director Review, no CAFC docket. The patent's own Google Patents record shows 96+ forward citations (Hill-Rom, Dane Technologies, Gatekeeper, Walmart Apollo, etc.) — i.e., the technology was influential, but the '840 claims were never the vehicle for that influence, and no citing party ever challenged the claims at the Board.

Red-herring warning for the docket search. Federal Circuit appeal numbers such as 2021-1840 (NuCurrent, Inc. v. [Samsung Electronics Co.](/litigations/by-defendant/Samsung%20Electronics%20Co.), Nos. 2021-1840 through 2021-1845) and the PTAB-litigation-investment line item "4771840" in a CourtListener financial-disclosure filing are coincidental digit matches, not references to this patent. Do not let anyone (or any automated docket alert) characterize those as an appeal of US 4,771,840.

Recommended next steps

1. Treat the absence of PTAB activity as dispositive of your defense posture, and say so plainly in any response to a demand letter. The correct framing is not "no IPR was filed, so the patent is strong" and not "an IPR canceled the claims." It is: no AIA trial exists because the patent lapsed effective 1996-09-25 for failure to pay the 8-year maintenance fee, and a later USPTO entry (2018-01-30) confirms expiration under 37 CFR 1.362. There is no live right to infringe.
2. If a plaintiff (or a letter) cites claims 1–5, quote the disposition precisely rather than paraphrasing it. There is no FWD to link — the operative public records are the Google Patents legal-status timeline (patents.google.com/patent/US4771840/en) showing the REMI → LAPS → FP chain and the 1996 lapse, and the USPTO PatentCenter file for Application 07/038,538 (patentcenter.uspto.gov), which contains the status history and no PTAB tab. Do not invent an FWD citation; none exists.
3. Do not brief invalidity as your lead argument. The threshold defect is expiration, not anticipation/obviousness. The '840 patent's own specification distinguishes prior art US 3,524,512 (Voeks) and US 4,020,916 (Noble) on turning radius (both are among the 8–9 references cited on the face), so a validity fight is winnable on paper — but you should not have to litigate validity against an expired patent at all.
4. Flag any newly-indexed filing for verification, and confirm the negative independently if the stakes demand it. Your own constraints require treating the structured ODP list as canonical, and it is empty; my web checks (IPR numbers, "Orthokinetics"/"Keller" petitioner searches, and PTAB E2E-facing results) returned nothing tying any trial number to US 4,771,840. For a certified negative, run a direct query on PTAB E2E / PTAB Center (Patent Trial and Appeal Board, https://ptacts.uspto.gov/) and CourtListener (https://www.courtlistener.com/) using both "4771840" and "4,771,840," and cross-check the USPTO Open Data Portal trials endpoint. If any proceeding surfaces that the ODP ingest missed, alert me — it would be materially relevant, since no AIA trial on this patent is expected to exist.

Confidence and caveats. High confidence that no AIA trial proceeding exists and that none can meaningfully exist going forward, grounded in (a) the canonical ODP empty result, (b) the 1996 lapse, and (c) the pre-AIA/PGR and non-financial/CBM ineligibility. This is a search-based negative, not a certified absence: I cannot rule out an unindexed, pre-digital-era administrative filing, and the ODP ingest may lag very recent submissions. No contradiction was found between this section and the previously generated summary or litigation sections — all three converge on "no litigation, no PTAB activity, patent lapsed 1996."

I'll verify the assignment record for this patent against assignment-indexing sources.

Assignment & Ownership Chain — U.S. Patent No. 4,771,840

Source basis and limits: The authoritative record available to me is the Google Patents legal-events/citation file for US 4,771,840 (which mirrors the USPTO assignment record) plus corroborating third-party index pages (uspto.report). My searches against Assignment Center–indexed content (assignment.uspto.gov), legacy-assignments.uspto.gov, and general web indexes returned only the single 1987 assignment. My search budget exhausted before I could execute a final live query of the Assignment Center UI at https://assignmentcenter.uspto.gov/ or pull the recorded cover sheet PDF for Reel 004692 / Frame 0472. Where a field (notably the correspondent of record) is not in the record I could retrieve, I say so rather than guess.

Inventors

Unusual-pattern check: The "all inventors departing the original assignee within 12 months of filing" tell cannot be assessed here — there is only one inventor, and no employment-departure, personnel, or subsequent-assignment data exists in any surface I could reach. Unclear / not determinable. Nothing in the record suggests a multi-inventor team, a fire-sale of a portfolio, or a pre-filing departure.

Original assignee

• Entity as named on the issued patent: ORTHOKINETICS (recorded as "ORTHOKINETICS, WAUKESHA, WI A CORP. OF WI" on the assignment cover record; Google Patents lists the current assignee as "ORTHOKINETICS / ORTHOKINETICS Inc").
• Primary line of business: Mobility products. The patent's own specification places the invention squarely in that space ("tractor unit for a supermarket shopping cart" for the handicapped), and the assignee operated in power wheelchairs, scooters, and lift chairs. Trade press identifies Ortho-Kinetics, Waukesha, Wisconsin, founded by Ed Gaffney, as "a pioneering lift-chair manufacturer and scooter dealer that reigned as a powerhouse in the 1980s" and "a $40 million player in the 1980s." (HME News, "Ortho-Kinetics files to liquidate assets")
• ⚠ Naming-discrepancy flag (do not auto-correct): the patent record spells the assignee ORTHOKINETICS (one word, no hyphen); the trade-press entity is Ortho-Kinetics (hyphenated). Same city (Waukesha, WI), same industry, same era, and the founder's name matches the period — so the identity match is highly likely but not proven from the record I retrieved. I did not find a corporate-name-change assignment ("Change of Name" conveyance) recorded against this patent, which is what would have confirmed the spelling reconciliation.
• Current status: Not operating / wound up. HME News reports that in 2003 Ortho-Kinetics "filed papers to liquidate its assets in state court," with a receiver appointed under [Wisconsin] Chapter 128 on January 31, 2003, while the company sought a buyer. The patent, however, had already lapsed in 1996 — seven years before the receivership — so no patent asset value was available to the receivership estate.
• Did they ship a product embodying the claims? Unclear. The company demonstrably sold scooters and lift chairs, and the patent's detailed disclosure (26-inch pivot-to-power-axis dimension, ±30° yaw bumpers, differential drive, PWM regenerative braking, fail-safe spring-set brake) reads as an engineered production design rather than a paper concept. But I found no documentary evidence (brochure, product literature, registration, or specimen) confirming that the articulated shopping-cart tractor unit of claims 1 or 5 was ever commercially sold. Flag as an open question rather than asserting a product.

Assignment timeline

There is exactly one recorded assignment in the chain.

• 1987-04-14 (executed) / recorded 1987-04-15 — Reel 004692 / Frame 0472
  • Conveyance: Assignment (Assignment of Assignors' Interest)
  • Assignor: Richard A. Keller (sole inventor)
  • Assignee: ORTHOKINETICS, Waukesha, WI, a corporation of Wisconsin
  • Correspondent: Not exposed in the record I could retrieve. The legal-events entry carries only the free-format text ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:KELLER, RICHARD A.;REEL/FRAME:004692/0472, with effective date 1987-04-14. Google Patents likewise does not surface a correspondent for this vintage. The recorded correspondent (attorney/firm on the cover sheet) would need to be pulled directly from the Reel 004692/Frame 0472 cover-sheet image in Assignment Center — I could not complete that retrieval. Recurrence test therefore cannot be run; do not treat the absence as evidence of anything. (One data point that is not the recording correspondent: the patent's prosecuting attorney/agent firm of record was Fuller, Puerner & Hohenfeldt, per the printed front page.)
  • Context: Original inventor-to-company assignment; internal/employment assignment contemporaneous with filing. Not a fire-sale, not a transfer to an asserter, not a change of name, not a security interest.

No other assignments, security agreements, mergers, name changes, licenses, releases, or corrections are recorded against US 4,771,840. The remaining legal events are purely maintenance-fee and status entries:

Anticipated expiration is recorded as 2007-04-15 (full 20-year term), but the enforceable right ended in 1996. Critically for the NPE analysis: the patent lapsed while still in ORTHOKINETICS' hands, 1996 being 7 years before the 2003 receivership. There is no post-lapse transfer of any kind.

This is itself the finding your instructions anticipated: only the original assignment exists, and the original assignee remained the owner of record through lapse.

Timeline diagram

timeline
    title Ownership of US 4771840
    1987 : Richard A Keller executes assignment
         : Filing date 1987-04-15
    1988 : Patent US 4771840 issues
    1991 : 4th year maintenance fee paid
    1996 : Lapse for unpaid maintenance fee
    2003 : Ortho-Kinetics receivership reported
    2018 : USPTO records expiration under 37 CFR 1.362

NPE / troll-pattern signals

Verdict

Insufficient data (only the original assignment)

The entire recorded chain consists of a single link: the inventor-to-company assignment executed 1987-04-14 and recorded 1987-04-15 at Reel 004692 / Frame 0472, conveying Richard A. Keller's rights to ORTHOKINETICS of Waukesha, Wisconsin. There is no post-issuance assignment of any kind — no NPE takeover, no security interest, no name change, no aggregation — and the patent lapsed for non-payment effective 1996-09-25, seven years before the assignee's reported 2003 Wisconsin receivership. That record supports exactly one conclusion about ownership: the patent died in the hands of its original operating-company assignee, which is the inverse of every NPE-pattern signal on the checklist. What keeps this short of a firmer "operating-company, unasserted" characterization rather than "insufficient data" is that the recorded correspondent on Reel 004692/Frame 0472 was not retrievable in my searches and I could not confirm or deny any product embodying the claims.

Verify / complete the record at: USPTO Patent Assignment Search (Assignment Center) or the legacy interface assignment.uspto.gov/patent — search Patent Number 4771840; the single hit is Reel 004692, Frame 0472. Pulling the cover-sheet image there will supply the correspondent of record field I was unable to capture.

Contradiction flag: None. This section is fully consistent with the two previously generated sections — the 1996 lapse, the absence of any CAFC 2026 docket, and the "no litigation located" finding all align with a chain that never left the original assignee. Nothing found here disturbs the earlier (apparent) CAFC 2026 / docket reference; I reiterate that no Federal Circuit 2026 matter involving this number was located, and the 1996 lapse makes such a matter legally implausible.

I'll research each cited prior-art reference to give accurate bibliographic data and claim-mapping. Let me run targeted searches.

Let me research the remaining cited references.

Prior-Art Analysis — U.S. Patent No. 4,771,840 ("Articulated power-driven shopping cart")

Scope note. Per the operating rule to prioritize live search results, I re-pulled the front-page citations via the Google Patents records and USPTO.report. My search budget was exhausted partway through, so the last three references (US 4,020,916; US 4,570,739; US 4,633,962) are characterized from the authoritative patent text plus general knowledge, flagged where confidence is lower. I did not uncover any cited reference that the earlier summary did not already list, and I found no contradiction with the previously generated sections — the bibliographic data below is consistent with them.

Claim framework (from the prior sections, not repeated in full). There are five claims; independent claims 1 and 5; dependent chain 1→2→3→4. Every reference below was published before the '840 filing/priority date of 1987-04-15, so all nine entries qualify as pre-AIA § 102(a)/(b) prior art. Note that US 4,570,739 B1 (the reexamination certificate, 1994) is not itself prior art — it post-dates the filing — but shares the identical disclosure of US 4,570,739 A.

1. Cited references — full citations, dates, descriptions

Sources: https://patents.google.com/patent/US2354576A/en, .../US2867449A/en, .../US3190386A/en, .../US3524512A/en, .../US3575250A/en (and https://uspto.report/patent/grant/3575250); the remaining entries are from the authoritative patent text provided.

2. Element-by-element claim mapping (§ 102)

The critical point for § 102 is that anticipation requires every element of a claim in a single reference. The distinguishing element of independent claim 1 is the specific coupling: a ball-joint male member on the cart frame near the rear casters + a ball-socket female member on the tractor frame giving "unhindered yaw, pitch and roll," tied to the pivot-axis-to-power-axis distance limitation. Independent claim 5's distinguishing element is the U-bolted, U-shaped clamp-on bracket structure.

Claims 2 and 4 specifically. No cited reference discloses the claim-2 bumper structures that coact with the cart frame to limit yaw and prevent jackknifing, nor the claim-4 pivotally mounted, rotation-limited seat that prevents the CG from shifting rearward of the pivot axis. Those features appear to be novel over all nine references, which is consistent with the claims having issued over them.

3. Ranking — "most relevant prior art"

1. US 3,524,512 (Voeks) — by far the closest. Same problem, same commercial context (ride-on powered tractor that detachably drives a conventional shopping cart), same seat + electric-drive architecture. The only differences from claim 1 are the coupling mechanism and the pivot/power-axis distance limitation.
2. US 2,867,449 (Shawver) — articulated powered unit + interchangeable load carrier; supports obviousness of an articulated powered tractor pulling a load-bearing cart.
3. US 4,020,916 (Noble) — self-propelled shopping cart with seat + electric motor; primary art on the seat/propulsion combination.
4. US 3,575,250 (Dykes) — quick-connect hitch for a self-propelled electric vehicle to varied wheeled devices; relevant to the detachable-coupling and battery-mount sub-combinations.
5. US 4,633,962 (Cox) — "articulated" vehicle concept, relevant to the articulation idea generally.
6. US 3,190,386 (Swinny) — motorized shopping cart with short turning radius; relevant to the stated objective but structurally remote (self-powered, non-articulated).
7. US 4,570,739 (Burke) — personal mobility vehicle; relevant only to the seat/platform environment.
8. US 2,354,576 (Clark) — rider trailer with hook coupling; marginal background art.

4. Bottom line on § 102 vs § 103

• No cited reference, alone or read with the others, appears to anticipate independent claim 1 under § 102. The ball-joint male/female coupling producing "unhindered yaw, pitch and roll," combined with the pivot-axis-to-power-axis distance limitation, is not disclosed by any of the nine references. The examiners evidently agreed, since claim 1 issued over all of them.
• No cited reference anticipates independent claim 5, whose U-shaped, U-bolted clamp-on bracket (legs fitting within the cart frame, clamped to horizontal and upwardly extending runs) is a specific structural arrangement absent from the references.
• The realistic challenge is § 103 obviousness, not § 102 anticipation. Voeks ('512) + Shawver ('449) + Dykes ('5250) collectively teach (i) a ride-on powered tractor that detachably drives a conventional shopping cart, (ii) an articulated powered unit towing a load carrier, and (iii) a quick-connect hitch joining a powered electric vehicle to wheeled devices. A ball-and-socket coupling was a well-known articulation device in the art, which is where a § 103 case would focus — but that combination argument must still overcome the claim-1 distance limitation (spec teaches ~26 in. for 8–10 ft aisle centerlines) and the claim-5 bracket specifics.
• Dependent claims 2 (bumpers) and 4 (rotation-limited pivoting seat) have no counterpart in any cited reference and would survive on these references standing alone.

5. Caveats / uncertainty

• Search-budget limitation (explicit): I could not complete targeted pulls on US 4,020,916, US 4,570,739, and US 4,633,962. Their bibliographic data (number, title, inventor/assignee, filing and publication dates) is corroborated by the authoritative patent text, but my one-line internal descriptions for those three are medium-confidence and should be verified against their full texts before being relied on for a written § 102/§ 103 opinion.
• No prior-art reference was auto-corrected. Numbers are reproduced exactly as they appear in the '840 citation list (including the dual US 4,570,739 A / B1 entries).
• § 102 legal standard: Even where a reference shares the purpose of '840 (e.g., Voeks), purpose/field overlap is not anticipation; the missing claim elements control.
• Contradiction flag: none. This analysis is consistent with the earlier summary (five claims; 1 and 5 independent; patent lapsed 1996) and the litigation section (no live enforcement), and it does not disturb those conclusions.

I'll ground the §103 mapping by pulling the actual disclosures of the face-cited references before building combinations.

Obviousness analysis — US 4,771,840 (Keller), 35 U.S.C. § 103

Threshold framing. This patent was filed 1987‑04‑15, so pre‑AIA § 103 governs (Graham v. John Deere factors; TSM as informed by KSR Int'l v. Teleflex). Practically, this is an academic/defensive exercise: the patent lapsed for non‑payment effective 1996‑09‑25 and expired 2007‑04‑15, so there is no damages remedy and no realistic post‑grant challenge (PGR never applied — pre‑AIA filing; an IPR is theoretically possible against an expired patent but offers no practical remedy). The exercise is nonetheless useful because the nine references cited on the face are the same art the examiner had, so any § 103 case here is a "reconsideration" argument — which means it must be built on the combinations the examiner may not have explicitly articulated, and on the admissions in the applicant's own Background.

Date note (flag): the current task states April 26, 2026, while the system context gives today as 2026‑10‑01. Immaterial to the analysis, but flagged per instructions.

1. The references and what each supplies

Not prior art (flag): the "Cited By" documents (Stringer '5,573,078; Neuling '6,003,625; Dane '8,360,459; Gatekeeper '8,894,086; etc.) all post‑date 1987‑04‑15 and cannot be used under § 102/§ 103 against this patent. They are relevant only to the "predictable result" narrative — later artisans repeatedly and independently arrived at the same powered tractor + articulated hitch + supermarket cart architecture.

2. Claim 1 — element mapping and combinations

Combination A (strongest): Voeks '512 in view of Clark '576 and Cox '962.
Combination B (alternative): Noble '916 in view of Shawver '7449 and Cox '962.

Motivation to combine (KSR rationales):

1. Same field / same problem. All references are in light‑vehicle and cart‑towing mechanics; '512, '916, Swinny are all supermarket‑cart propulsion. Combining a known articulated towing coupling with a known cart tractor is use of familiar elements according to known methods yielding a predictable result.
2. The specification supplies the motivation. The '840 Background concedes that '512 and '916 each teach a seat plus electric propulsion for a shopping cart, and criticizes them only for turning radius. An applicant's admission of the prior art's teachings is a legitimate starting point; the remaining delta is a parameter selection, not a new mechanism.
3. A recognized problem, one obvious solution. Hard‑to‑maneuver articulated vehicles in narrow aisles is the stated problem; increasing the angular freedom and relocating the pivot closer to the drive axle are the two textbook levers for shrinking a turning radius. Cox '962 shows the art already solving "mobility vehicle needs multi‑axis articulation" with pivots; Clark '576 and Shawver '7449 show the art already using free‑moving, quick‑attach couplings.
4. Design incentive / obvious to try. A supermarket operator wants a mobility aid that (a) uses the existing cart fleet unmodified and (b) fits standard aisles. Claim 1's own functional limitation signals exactly the constraint the designer of ordinary skill would optimize to.
5. Reversal of parts. Claim 1 places the ball (male) on the cart and the socket (female) on the tractor — the reverse of the conventional trailer arrangement (ball/hook on the towing vehicle, coupler opening on the towed vehicle, as in Clark '576 and Shawver '7449). Switching which of two mating members carries the ball, with no asserted new result, is a classic reversal/rearrangement of parts. (MPEP 2144.04(VI).)

The metric limitation is the crux — and it cuts against patentability.

• The claim recites a result ("turning radius adequate …"), and the specification's only concrete number (26 inches) is not in the claim. As issued, claim 1 covers any pivot‑to‑power‑axis spacing that "works" in a supermarket — i.e., it is broader than the asserted invention and readily read onto heavily optimized prior‑art geometry.
• Turning radius varies monotonically with the pivot‑to‑drive‑axle distance — a result‑effective variable. Where the prior art discloses the general structure, discovering the optimum or workable value by routine experimentation is not inventive (In re Aller; In re Boesch; In re Applied Materials, 692 F.3d 1289 (Fed. Cir. 2015)). The spec's stated basis (8–10 ft aisle centerlines) is a known supermarket design constant, making the "dimensioning" step ordinary design work.

3. Claims 2–4

Claim 2 (yaw‑limiting bumpers). This is the weakest link for a two‑reference rejection, and I will not overstate it: none of the nine face references is shown (in the record available to me) to disclose limit stops acting between the two articulated vehicle sections. A rejection here would most likely rest on (a) Burke '739 or an additional trailer‑hitch/steering‑stop reference not on the face, or (b) KSR common sense — jackknifing and pinch points in articulated/trailer vehicles were notoriously known problems, and mechanical stops are the most predictable available solution. Note also the internal tension with claim 1: claim 1 requires "unhindered yaw," while dependent claim 2 adds yaw limiting (±30°). A dependent claim cannot broaden claim 1, but a limitation that appears to contradict "unhindered" invites a § 112 ¶ 2 question and, for our purposes, demonstrates that yaw limitation was treated by the drafter as a mere optional add‑on — i.e., an obvious expedient. This tension should be flagged in any written analysis.

Claim 3 (foot platform + seat whose occupant CG is forward of the power axis). Strong. Voeks '512 independently discloses seat (28/38) + floor platform (26) + battery (68) + motor (58) in the cart‑tractor itself; Noble '916 discloses bench seat over the rear wheels + a foot platform between basket and seat. Cox '962 goes further, disclosing a seat 48 whose pivotal axis "is located only slightly rearwardly of the articulated pivotal axis" — precisely the geometry of positioning a seated occupant relative to the articulation/power axis. Motivation: load the coupling and the drive wheels to preserve traction and limit pitch — a recognized stability requirement (Voeks's truck is inherently nose‑heavy by construction). Predictable result.

Claim 4 (seat pivotally mounted, stand‑up reach, rotation limited so CG cannot shift rearward of the pivot axis). Cox '962 discloses a pivotally mounted seat (post 52 journalled in bearing 55) in a powered mobility vehicle; swivel/stand‑up seats were conventional in mobility vehicles (Burke '739 environment). Limiting the arc of a pivoting seat to protect stability is a safety‑driven design choice with a predictable result. Obvious.

4. Claim 5 — the clamp‑on bracket

Elements: cart with basket, handle portions, front casters, horizontal caster‑supporting runs and upwardly extending frame runs supporting the basket (standard cart geometry, per '512/'916/Swinny); powered tractor; coupling giving yaw/pitch/roll and defining a pivot axis; generally U‑shaped bracket whose legs fit within the cart frame, clamping members fixed to the legs, clamped by U‑bolts to the horizontal and upwardly extending runs.

• Shawver '7449 teaches the same functional concept: a detachable mounting of a powered unit to a load‑carrying unit, with bail/clip hardware and an over‑center lock — hardware removably mounted to a frame.
• Clark '576 supplies the express motivation: attach the auxiliary vehicle "expeditiously … without the necessity of making material structural alterations" in the host vehicle. That is precisely the stated object of claim 5.
• The U‑bolt itself is a commodity clamping fastener; using it to clamp a bracket to tubular frame runs is known work for a known purpose (KSR). Fitting the bracket legs "within" the cart frame is dictated by the cart's existing geometry and requires no more than ordinary mechanical adaptation.

Claim 5 therefore stands or falls with claim 1; if the articulated coupling is obvious, the clamp‑on implementation is a fortiori obvious.

5. Anticipation check

No single reference appears to disclose every element of claim 1 — in particular, none of the nine is shown to disclose a ball‑and‑socket coupling positioned at the cart's rear casters, with the male member on the cart. Voeks '512 comes closest structurally but deliberately lifts the cart's rear wheels off the floor (a different architecture from claim 1, which leaves the cart supported on its own casters). Anticipation would be hard to sustain; § 103 is the viable theory, and it must be built as a combination.

6. Secondary considerations / objective indicia

I found no evidence of record supporting a nexus‑based rebuttal: no commercial‑success, licensing, copying, industry‑praise, or failure‑of‑others evidence, and no assignment beyond Keller → ORTHOKINETICS (1987). To the contrary, the patent's lapse for non‑payment in 1996 — nine years after filing and eight years after issue — is inconsistent with a commercially successful, enforceable product line and is weak evidence of the absence of investment in the invention. There is also no teaching‑away in any reference; Voeks, Clark, and Shawver each point toward detachable, freely articulating couplings.

7. Bottom line

Strongest counter‑argument the patentee would make: none of the art shows a ball joint coupling per se at the cart's rear casters, and the art that does articulate (Cox, Shawver) does so about upright pivots or rockers rather than a three‑axis ball. The rebuttal is that three‑axis ball couplings were ubiquitous in towing practice (common knowledge; Clark's loose hook/eye is a crude multi‑axis analogue), that substituting a ball‑and‑socket for a pin‑and‑bearing articulation is a predictable mechanical substitution, and that the patent's own specification identifies only turning radius — not the coupling type — as the point of novelty.

8. Caveats and confidence

• I verified full text (via Google Patents / patentimages) for Voeks '512, Noble '916, Shawver '7449, Clark '576, and Cox '962. I did not verify the full texts of Burke '739, Swinny '1900386, or Dykes '3575250 before exhausting my search budget; statements about them rest on their titles/dates plus the '840 specification's own descriptions and Noble '916's citation of Dykes. Any rejection relying on '739 or '1900386 should be re‑verified against the actual columns.
• No reference in the record is confirmed to disclose the ball‑and‑socket form of coupling; my case for that element rests on common‑knowledge trailer practice plus Clark/Shawver. If a ball‑hitch‑in‑cart context reference exists (US 3,439,764 "Power caster for moving trailers" and US 4,210,217 "Self‑propelled steering device for trailers," both pre‑1987, are plausible candidates from the Similar Documents list), it should be pulled and used — I did not retrieve their texts.
• Confidence: high for claims 1, 3, 4, 5 on the stated combinations; moderate for claim 2.
• Contradiction flags: (a) date discrepancy noted in § 0 above; (b) the claim 1 "unhindered yaw" vs. claim 2 yaw‑limit tension noted in § 3, which the prior patent summary did not address and should now be treated as a live issue; (c) the "Cited By" documents are not prior art to this patent, notwithstanding their placement on the Google Patents page alongside the citation lists — do not cite them as § 102/§ 103 art.