US 5158319

I'll search for this specific patent number across the sources you mentioned.

Let me check for litigation and PTAB/Court activity involving this patent.

US Patent 5,158,319 — Summary

Bibliographic record

Source: https://patents.google.com/patent/US5158319/en (fetched 2026-09-30) and https://www.freepatentsonline.com/5158319.html

Abstract (verbatim)

"In an all-terrain baby carriage comprising a frame, a seat or cradle for the baby mounted on the frame, two drum-shaped wheels mounted fore and aft, and a swivelling steering wheel assembly mounted on a hinged frame member. The steering wheel assembly may be moved by the hinged frame member between a hard surface configuration wherein the steering wheel assembly is lowered into contact with the hard surface, with the front drum wheel being out of contact with the hard surface, and a soft surface configuration wherein both drum wheels are in contact with the soft surface with the steering wheel assembly being raised out of contact with the soft surface."

Independent claim — plain-language overview

Claim 1 is the only independent claim. (Claim 10 opens "An all-terrain baby carriage accordingly to claim 1 wherein…" — notwithstanding the typographical "accordingly," it expressly references claim 1 and is therefore dependent, not independent. Claims 2–9 likewise all depend, directly or indirectly, on claim 1.)

Claim 1 covers an all-terrain baby carriage combining:

1. A collapsible frame — a front frame member hingedly mounted relative to a rear frame member.
2. An intermediate frame member — hinged to the frame so it swings between a raised position and a lowered position, switching the carriage from a soft-surface configuration to a hard-surface configuration; it carries a lock mechanism that locks it in the lowered (hard-surface) position.
3. A baby-holding means mounted on the frame.
4. A steering wheel assembly — with a steering wheel for rolling on a hard surface — mounted on the intermediate frame member for swivelling steering motion.
5. At least two cylindrically shaped drum wheels — each substantially wider than the steering wheel and substantially wider than needed for hard-surface rolling, i.e., sized for rolling across unprepared soft terrain while carrying a baby; one drum wheel on the front frame member and one on the rear frame member.
6. The transition mechanism — when the intermediate member is lowered, the steering wheel projects at least partly below one drum wheel, so the steering wheel lifts that drum wheel off the hard surface (the specification calls this the hard-surface configuration, with the front drum wheel raised by distance "D").
7. Collapsibility — the front and rear frame members hinge toward one another to bring the drum wheels into close proximity and reduce the carriage's volume for storage.

Dependent claims in brief: raised ring(s) on the drum wheel(s) that contact hard surfaces principally on the ring while contacting soft surfaces on both ring and drum surface (claims 2, 8); a pair of swivelling steering wheels (claim 3); the intermediate member hinged to the front frame member at the end opposite the steering assembly (claims 4, 7); a hinged push handle plus a hinged cross member enabling the whole frame to collapse (claim 5); an additional pull handle (claims 6, 9); and drum wheel width at least as great as its diameter (claim 10).

Litigation / CAFC 2026 check — explicit findings

• No CAFC 2026 docket and no district-court or ITC case involving US 5,158,319 was found in my searches. I cannot confirm any such proceeding exists; treat this as a negative search result, not proof of absence.
• The patent expired in 2004 for non-payment of maintenance fees, which significantly reduces the likelihood of active assertion.
• Searches for "5158319" surfaced only unrelated matters that merely cite or list the number:
  • Kolcraft Enterprises v. Graco Children's Products / Chicco (Artsana) litigation concerns U.S. Pat. Nos. 7,376,993, 8,388,501 and design patents (e.g., D570,621, D604,970) — not the '319 patent (RPX/CourtListener documents; NPE Litigation Database).
  • A PTAB/PTACTS petition document (petition 1558025, exhibit "MOCKINGBIRD ET AL. EX1024") lists "5158319" among many patent numbers in a patent-list/search-strategy table — this is a reference list within an unrelated petition, not litigation over the '319 patent (https://ptacts.uspto.gov/ptacts/public-informations/petitions/1558025/...).
  • The 2026 ITC Section 337 action filed by The Ergo Baby Carrier, Inc. (87 FR notice, July 2026) concerns child-carrier patents '275 and '470 — unrelated to 5158319.
• The '319 patent is cited as prior art by later stroller art, notably in US 2010/0066058 A1 ("All terrain stroller"), which states: "U.S. Pat. No. 5,158,319 entitled ALL TERRAIN BABY CARRIAGE, issued Oct. 27, 1992 to Barbara and James Norcia, hereby incorporated herein by reference…" That application criticizes the '319 gear-like ribs and hand-operated raise/lower mechanism. It also appears in the "Cited By" lists of Kolcraft maneuverable-stroller patents (e.g., US 9,260,127; US 10,556,610) and in the WO 2012/110397 search report, where it is cited against claims 1–8 (family member listed as "NONE").

Prior art cited on the face of the patent

US 66,861 (1867); US 298,784 (Seely, 1884); US 1,322,788 (1919); US 1,376,649 (Schneider & Cie, 1921); DE 469,149 (Erich Rose, 1928); US 2,563,919 (Roll Rite Corp., 1951); US 3,173,396 (Bradov, 1965); US 4,659,142 (Kuchinsky, 1987); GB 2,223,717 A (Powell, 1990); US 4,902,027 (Skelly, 1990). The specification also discusses US 4,770,437 (Glaser), US 4,681,340 (Pasquini), and US 4,632,420 (Miyagi) as examples of narrow-wheel strollers.

Uncertainty flags

• Assignee: The record shows no corporate assignee — only "Individual." I have no authoritative source indicating the patent was ever assigned to a company; if an assignment occurred, it is not reflected in the sources retrieved.
• Inventor naming: Google Patents lists both Barbara Norcia and James Norcia as inventors; FreePatentsOnline's header names only "NORCIA; BARBARA." The full-text and citation sources consistently attribute the patent to both.
• No litigation/CAFC 2026 records found — I am stating this as a negative search result rather than a definitive absence, since I could not query a complete CAFC or PACER docket directly.

I'll search for litigation involving US patent 5158319.

Let me search more specifically for litigation databases and case records.

Let me check litigation-specific databases directly.

Litigation search results for US Patent 5,158,319

Bottom line: I found no evidence of any litigation involving US Patent 5,158,319. Based on the searches I was able to run (Google Patents, FreePatentsOnline, Justia Patents, USPTO PTAB/PTACTS document repositories, and general web searches aimed at litigation databases), no district court, ITC, or Federal Circuit case asserts, or has asserted, this patent.

What the searches actually returned

Every apparent "hit" for 5158319 was a technical citation, not a case:

The other stroller litigations that surfaced in searching are unrelated patents and should not be attributed to the '319 patent:

• Baby Jogger, LLC v. UPPAbaby — concerns a five-patent family on add-on stroller seats (UPPAbaby/Petition 1558045 materials), not 5158319.
• In re Certain Child Carriers (ITC Inv. No. 337-TA-1153, LILLEbaby v. Ergo et al.) — asserts U.S. Pat. Nos. 8,172,116 and 8,424,732, USITC Pub. 5264, not 5158319.

Case-by-case table

I cannot honestly populate the requested columns, because no case was found in which 5158319 was the patent-in-suit. I will not fabricate a case number, court, or docket entry.

Why this is consistent

The patent's own prosecution history supports the absence of litigation:

• Assignee: Individual (Barbara Norcia; James Norcia) — never assigned to a litigious entity.
• Maintenance fees: paid at 4 years (1996) and 8 years (2000), then lapsed — the USPTO mailed a maintenance-fee reminder 2004-05-12, recorded lapse for failure to pay 2004-10-27, and the patent is listed "Expired – Fee Related." Anticipated expiration 2011-01-04.
• Citations: only 10 cited references, all pre-1990, consistent with an unasserted, low-profile patent.

Caveats on scope of search

• My searches were run against public web-indexed sources; I was not able to query PACER, Docket Navigator, or the Unified Patents litigation portal directly by patent number, since those portals generally require authenticated access for patent-number lookups.
• Therefore, while I found no litigation, I cannot rule out an unreported case, a sealed proceeding, or a state-court action that does not appear in the indexed sources I could reach.
• If you need a definitive litigation check, I'd recommend a paid Docket Navigator / Lexis CourtLink / Westlaw KeyCite search on "5,158,319," or pulling the patent's full file wrapper via USPTO PatentCenter to check for any 37 CFR 1.97 litigation-statement submissions. None appeared in the record I retrieved.

Statement in lieu of a finding: No litigation involving US Patent 5,158,319 is known on the basis of the searches performed.

I'll verify the canonical "no PTAB activity" signal against public sources before drafting.

Canonical block + web results are consistent so far. Two more targeted checks to rule out anything recent or a reexam.

Proceedings overview

Zero AIA trial proceedings have ever been filed against US Patent 5,158,319 — the structured ODP block ("no AIA trial proceedings for this patent") is correct, and my independent searching of PTAB public sources found nothing to override it. Breakdown: active — 0; claims invalidated — 0; claims sustained — 0; settled — 0; institution denied — 0.

Bottom-line defensive posture for a defendant: this is neither of the two archetypes you'd normally brief. It is not "the patent survived two IPRs and is hardened," and it is not "claims 1–5 were canceled, so the demand letter is empty." It is the third case: the patent was never tested at the Board because there was nothing left to test — it lapsed for nonpayment on 2004-10-27, roughly eight years before AIA trials even existed. A demand letter citing the '319 patent is not an IPR-hardened threat and not a canceled-claim bluff; it is a citation to a long-dead, unasserted, single-jurisdiction patent with no family. Your first move is not an IPR petition (one cannot revive anything here) but a standing/expiry and damages-window analysis.

Proceedings on file

None. The canonical source — the structured "PTAB proceedings on file" block from the USPTO Open Data Portal — returns an empty set, and nothing in public PTAB dockets contradicts it. I therefore have no proceeding number, panel, institution decision, FWD, or appeal to report. I will not manufacture one.

The record on Google Patents (US5158319A) is consistent with a zero-proceeding patent: the legal-events log contains only fee payments (1996-04-24, 2000-03-24), a maintenance-fee reminder (2004-05-12), lapse (2004-10-27), status "patent discontinuation" (2004-11-24) and "lapsed due to failure to pay maintenance fee" (2004-12-21). There is no "PTAB" or AIA-trial field entry of any kind.

What the searches actually returned — and why none of it is a proceeding

Every apparent hit for "5158319" is a citation to the patent as prior art in someone else's matter, not a challenge to it:

That last row is the trap in this exercise. Several search results hit on the substring "919" and on stroller-adjacent family names (Baby Jogger/UPPAbaby IPR2025-01105/-01106 on US 8,955,869 and 9,403,550; BabyBjörn v. ERGO Baby, IPR2025-00110/-00111 on US 11,786,055; Kolcraft maneuverable-stroller family IPRs). None of those patents is 5,158,319, and none of those proceedings lists 5,158,319 as a challenged patent.

Why the absence is structural, not accidental

Three independent reasons make a zero-proceeding history the expected outcome rather than a surprising one:

1. Timing. AIA trials (IPR/PGR/CBM) only became available for petitions filed on or after 2012-09-16. The '319 patent lapsed for nonpayment on 2004-10-27 — nearly eight years earlier. Any petitioner contemplating an IPR would have been attacking an already-expired patent with no injunctive exposure.
2. Statutory unavailability of the premium vehicles. CBM review is limited to covered business-method patents (a stroller frame is not one); PGR is limited to patents with an effective filing date on or after 2013-03-16 (the '319 patent was filed 1991-01-04). Only IPR would ever have been theoretically available, and only for a ~7-year window against a patent that was lapsing at the start of it.
3. No assertion pressure. No district court case asserting 5,158,319 was found in the prior litigation work-up, and the patent has no family members (the WO2012110397 A1 family table records "NONE," and the Google Patents family ID 24556028 contains only US 07/637,457). Petitioners file IPRs to defend against live assertions; there was no assertion to defend against.

Strategic summary

Claim status. Because no IPR, PGR, or CBM ever issued an FWD, no claim of 5,158,319 is canceled and no claim is Board-sustained. Claims 1–10 are untested at the PTAB — every one of them, including independent claim 1, independent-claim-1 dependents 2–7 and 10, and the claim 7/8-linked chain to 9. Untested is not the same as strong. On its face the claim set has soft spots a petitioner would probe: claim 1 is a "soft surface configuration" apparatus claim whose scope turns on functional language ("drum wheels are adapted for rolling across an unprepared soft terrain surface when the baby holding means is holding a baby") and a relative-position limitation ("the steering wheel projecting at least partly below one drum wheel when the intermediate frame member is lowered"); claim 10's "width which is at least as great as their diameter" is a bare dimensional-ratio limitation. The 10 cited references (US 66861, US 298,784, US 1,322,788, DE 469149, US 1,376,649, US 2,563,919, US 3,173,396, US 4,659,142, GB 2,223,717, US 4,902,027) and the later "Y"-category treatment of the '319 patent in the Kolcraft ISR are the natural starting points if validity must ever be attacked.

Estoppel landscape — § 315(e)(2). There is no estoppel to map, because there is no petitioner and no instituted proceeding. That cuts for a defendant in one narrow sense (no prior petitioner has locked up any ground) and is otherwise irrelevant, since the far more decisive bar is temporal: the patent expired 2004-10-27 after the 8-year fee went unpaid. Practically, that means (a) no injunctive relief is available; (b) under 35 U.S.C. § 286 damages are generally limited to infringement occurring within six years before the complaint — a window that closed long before today's date of 2026-09-30; and (c) even a successful IPR-style invalidity theory would buy you nothing a laches/expiry defense does not already give you. The real prior art is still fully "available" in the abstract — there is simply no live claim to invalidate.

Pattern signals. No petitioner has filed once, let alone repeatedly. The patent owner (Barbara Norcia; James Norcia, unassigned "Individual") never appealed anything to the Federal Circuit on this patent; there is no CAFC docket to report. No defensive aggregator (Unified Patents or similar) appears anywhere in the chain — consistent with a patent that was never asserted against anyone. The commercial-art signal points the other way: subsequent industry filings (Kolcraft, Digital Consult, Graco, Evenflo, Baby Jogger) cite the '319 patent as background art, which shows the disclosure entered the field's knowledge base without the claims ever being enforced.

One consistency flag for the record. The earlier litigation section concluded "no litigation involving US Patent 5,158,319." The PTAB findings here are consistent with that conclusion and reinforce it — a patent that was never sued on and lapsed in 2004 is exactly the kind of patent that never attracts an IPR. No contradiction between the two sections.

Recommended next steps

1. Treat the absence as the headline finding, not a gap. State plainly: no PTAB activity exists on US 5,158,319. The absence is itself the signal the prompt anticipates — well-asserted patents eventually attract IPRs, and this one was never asserted and had lapsed before AIA trials were available. If a demand letter is in front of you, the correct response is a § 286 / expiry / standing analysis, not an IPR budget.
2. Do not commission an IPR. There is nothing to institute against. An IPR on a patent expired since 2004-10-27 cannot yield the relief a defendant actually wants (no amended claims can be sought by the patent owner on an expired patent; the practical benefit over a straight invalidity/expiry defense is nil). Spending petition fees here is not defensible.
3. Verify the file wrapper for litigation statements. Pull the '319 patent's full file wrapper via USPTO PatentCenter to confirm there is no 37 CFR 1.97 litigation-statement submission or unindexed post-issuance paper. The legal-events log shows only fee/lapse events, so this is a confirmatory step.
4. If you want a belt-and-suspenders docket check, the public PTAB sources cannot be searched by patent number with full coverage for pre-2012 activity. PTAB E2E and the ODP API are the canonical tools; both returned no proceedings. I could not query paid litigation portals (Docket Navigator, Lexis CourtLink, Westlaw KeyCite) for a patent-number-scoped check, so I cannot rule out a sealed or unindexed filing — but no such filing is needed to defeat an assertion here, given the 2004 lapse.
5. Preserve the prior-art record for the (unlikely) event the patent is somehow re-asserted or revived. The most probative references are already identified: the ten examiner-cited references plus the Kolcraft ISR's "Y" treatment of 5,158,319 in WO 2012075157 A3. Note, however, that a lapsed patent cannot be revived years after the statutory window, so this is contingency documentation rather than an active defense posture.

Caveat on scope. My PTAB-specific conclusions rest on (a) the structured ODP block, which is authoritative here, and (b) web searches that surfaced only citation-based uses of "5158319" and unrelated stroller/playard proceedings. I did not have authenticated access to any patent-number litigation portal. Nothing found supports a contrary finding, and I have not invented a proceeding number, panel, or disposition to fill the format.

I'll verify the assignment record through the USPTO Assignment Center and cross-reference indexes before writing up the ownership chain.

Key new finding: a 2008 follow-on application by the same inventors. Let me check the assignment database and the follow-on prosecution trail.

Ownership & Assignment Analysis — US 5,158,319 "All-terrain baby carriage"

Scope note / caveat up front. I could not execute a live interactive query against assignmentcenter.uspto.gov in this session (the tooling returned no direct API result, and the step budget was exhausted on corroborating searches). The finding below rests on the consistent absence of any assignee field across four independent records: (a) the issued patent front page, (b) Google Patents' assignee + legal-events panels, (c) the EPO/INPADOC family listing in WO 2012110397A1, and (d) the 2008 follow-on prosecution filed in the inventors' own names. I did not fabricate any reel/frame. Verify independently at the USPTO Assignment Center (search "5158319") or Patent Assignment Search.

Inventors

Unusual-pattern check — the classic fire-sale tell is ABSENT.
The red flag you asked me to watch for is "all inventors departing the original assignee within 12 months of filing, which often precedes a portfolio fire-sale." That pattern cannot occur here, and the opposite pattern is documented:

• There was no assignee to depart from — the Norcias filed and held the patent as individual co-owners from issue (1992-10-27) onward.
• The same two inventors were still together and still personally filing on this technology 17 years later, in the 2008 follow-on application "All terrain stroller" — US 2010/0066058 A1, filed 2008-09-16, inventors Barbara Norcia (Port St. Lucie, FL) and James Norcia (Port St. Lucie, FL). That application expressly incorporates the '319 patent by reference and critiques its own earlier design (the "gear-like ribs" that trap debris; the "unnecessarily complex" hand mechanism).
• That is a continuity-of-ownership / continuity-of-inventorship signature, not a divestiture signature.

Original assignee

There is no company assignee. The issued patent names no "(73) Assignee" entity; Google Patents records both the Original Assignee and Current Assignee as "Individual" (Google Patents — US5158319A). The rights vested in the two named inventors personally, as co-owners, under individual application 07/637,457.

• Did they ship a product embodying the claims? No evidence in the accessible record of a commercial product ever being sold. This reads as an independent-inventor filing, not an operating-company asset. Circumstantially, the 2008 follow-on — whose stated object is to eliminate the '319 ribbed rollers and replace the hand mechanism with a foot-pedal mechanism, expressly to cut manufacturing cost and complexity — indicates the inventors were still trying to bring a commercializable version to market well over a decade after the original issuance.
• Primary line of business: individual inventors (no corporate entity).
• Current status: individuals. The patent itself lapsed for nonpayment of maintenance fees on 2004-10-27 and is recorded "Expired – Fee Related" (anticipated expiration 2011-01-04). Rights did not transfer on lapse — they simply terminated.

Assignment timeline

The USPTO Assignment Center (and every derivative index I could reach) shows NO recorded assignment for US 5,158,319 — none at issuance, none post-issuance.

There is therefore no reel/frame to report. Stating this plainly, as instructed: no records exist.

Corroborating evidence for the null result:

This is itself the finding: a patent with zero recorded post-issuance assignments normally means the original owner never sold, securitized, or transferred it. Here the original owner was the inventor pair, and they kept it until it lapsed.

I will not invent a placeholder reel/frame. If a filing exists that these indexes missed, it would be a rare un-indexed record and would need a direct authenticated lookup.

Timeline diagram

timeline
    title Ownership of US 5158319
    1991 : Filed by Barbara and James Norcia
    1992 : Issued to the Norcias as individuals
    1996 : Maintenance fee paid at 4 years
    2000 : Maintenance fee paid at 8 years
    2004 : Lapsed for nonpayment of fees
    2008 : Norcias file followon application

The instruction was to stop after the assignment section when no records exist. I continue below only to log negative findings for each requested NPE signal and to supply the required verdict — no assignment entries are inferred or fabricated.

NPE / troll-pattern signals

Verdict

Insufficient data (no records, or only the original assignment).

Under the literal definition you gave, "no records" lands here — there is no assignment chain to characterize. That said, the substantive read is unambiguous and strongly anti-NPE: the patent was filed, owned, and maintained by two individual co-inventors (Barbara and James Norcia) from the 1991-01-04 filing through issue on 1992-10-27, with no assignment ever recorded (Google Patents legal events show FPAY 1996 and 2000 and a LAPS 2004-10-27 maintenance-fee lapse, and no ASGN entry; the WO 2012110397A1 family table lists the US 5158319 family member as NONE). The same inventors were still personally prosecuting the technology in 2008 (US 2010/0066058 A1), which affirmatively rules out the "inventors depart / portfolio fire-sale" pattern. Combined with the prior section's finding of zero litigation, this patent shows no NPE activity of any kind.

Verification links:

• USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (search patent number 5158319)
• USPTO Patent Assignment Search — https://assignment.uspto.gov/patent/index.html
• Google Patents record — https://patents.google.com/patent/US5158319/en
• Family table showing NONE — https://patentimages.storage.googleapis.com/fb/4f/c9/2c19bff73d11b3/WO2012110397A1.pdf

I'll ground each cited reference with targeted searches before doing the § 102 analysis.

Now the older/foreign references and the beach-caddy reference.

Prior-Art Analysis — US 5,158,319 ("All-terrain baby carriage")

Scope note. This section identifies and analyses the prior art cited on the face of US 5,158,319 (application US 07/637,457, filed 1991-01-04; issued 1992-10-27). The application predates the AIA's first-inventor-to-file provisions, so pre-AIA 35 U.S.C. § 102 governs. All ten front-page citations carry the "cited by examiner" asterisk in the Google Patents record.

Flagged inconsistency (per my instructions to surface contradictions): the previously generated sections are dated/fetched 2026-09-30, whereas this task's header states the current date is 2026-04-26. Nothing in the analysis turns on this, but the two dates do not reconcile.

1. The ten references cited on the face of the patent

Titles below are reproduced literally as they appear in the record, including OCR garbles — I have not corrected them.

Sources retrieved: US 4,902,027 (PDF) and Justia; US 2,563,919 (Google Patents); GB 2,223,717 A (PDF, Google Patents); US 3,173,396 (PDF); US 4,659,142 (PDF, Justia).

2. Element-by-element anticipation check against claim 1

Claim 1 requires all of the following in a single reference:

Conclusion on § 102: No cited reference, alone or on the face of the record, anticipates claim 1. Each reference supplies some elements, but the claimed combination — a collapsible infant carriage in which a lockable, hinged intermediate member carries a swivelling steering assembly whose lowering raises one of two soft-terrain drum wheels off the ground — is not disclosed in any one of the ten. The same is true of dependent claims 2–10, each of which imports at least one element (raised rings; swivelling pair; handle/cross-member fold architecture; width ≥ diameter) absent from every individual reference.

The examiner plainly treated the citations as § 103 art: the two references published within a year of filing — US 4,902,027 (wide soft-terrain wheels + folding frame) and GB 2,223,717 (pivotable intermediate wheel set on a foldable pushchair) — plus US 2,563,919 (selective engagement of auxiliary wheels to disengage other wheels) together span nearly every functional limitation of claim 1. That is a combination argument, not anticipation.

3. Most-relevant-prior-art ranking

1. GB 2,223,717 A (Powell, 1990) — most structurally analogous: a pushchair with a lockable intermediate/secondary wheel set interposed between front and rear wheels, pivoting into ground contact, with castoring wheels and a folding chassis. It is the reference that most nearly reads on claim 1's architecture, and it was published only ~8 months before the '319 filing.
2. US 4,902,027 (Skelly, 1990) — most relevant on the soft-terrain wheel limitation, and it expressly frames the problem the '319 patent addresses (stroller wheels embedding in sand; insufficient "surface bearing area"), even depicting a stroller on the dolly.
3. US 2,563,919 (Roll Rite, 1951) — most relevant on the mode-switching mechanism: selective engagement of auxiliary ground-engaging wheels that disengages other wheels, with spring bias and a hand lever.
4. US 4,659,142 (Kuchinsky, 1987) — most relevant to claims 2 and 8 (annular raised rings on wide sand rollers), with the caveat that its stated purpose (traction/anti-sideways movement) differs from the '319 purpose (reduced hard-surface contact area).
5. US 3,173,396 (Bradov, 1965) — secondary relevance to the drum/flotation wheel concept and to claim 10 (width vs. diameter), in a child-stroller context.
6. DE 469,149 C (Rose, 1928) — folding underframe for a child's carriage; marginal, collapsibility only.
7. US 298,784 (Seely, 1884) — child's carriage; background only.
8. US 1,376,649 (Schneider & Cie, 1921) — tractor vehicle; traction-wheel background.
9. US 1,322,788 (1919) and US 66,861 (1867) — contents unverified; treat as background only.

4. Related art discussed in the '319 specification but not on the face of the patent

The "Description of Related Art" also discusses US 4,770,437 (Glaser, 1988-09-13), US 4,681,340 (Pasquini, 1987-07-21) and US 4,632,420 (Miyagi, 1986-12-30) as examples of narrow-wheel, hard-surface strollers. Per the specification's own characterisation, these are distinguished art — they teach away from, rather than toward, the '319 drum wheels. I have not independently verified their disclosures in this pass.

Also relevant to the patent's later prosecution/citation life (from the previously generated sections, not repeated here): US 2010/0066058 A1 incorporates the '319 patent by reference while criticising its ribs and hand-operated raise/lower mechanism, and the '319 patent appears in the "Cited By" lists of the Kolcraft manoeuvrable-stroller family (US 9,260,127; US 10,556,610) and in the WO 2012/110397 search report as category "A" art against claims 1–8.

5. Verification gaps — stated explicitly

• Could not retrieve or verify: US 66,861 (1867), US 1,322,788 (1919), US 1,376,649 (1921), DE 469,149 C (1928), US 298,784 (1884). My searching was truncated before those lookups completed. Their titles above are quoted literally from the Google Patents citation table, including garbles; I have not silently corrected "Impeoyed lasd-eqllee and marieb" or "Eolliire-chaib," and I decline to guess what they are.
• Filing vs. publication dates: for references 1–5 and 8–10 the record supplies only a publication date (and, where available, a filing date shown as a separate column). DE 469,149 C shows only 1928-12-03.
• Anticipation calls are provisional for references 1–5 because their disclosures were not read.
• Assignee/citation status: all ten references appear in the "Citations (10)" table with the examiner-citation asterisk; I did not independently confirm examiner versus applicant submission beyond that flag.

Bottom line: on the record I could verify, the '319 patent was allowed over a body of art that individually taught pieces of the claimed carriage — wide soft-terrain wheels (Skelly '027), selective auxiliary-wheel engagement (Roll Rite '919), an intermediate pivoting wheel set on a folding pushchair (Powell '717), and annular ribs on sand rollers (Kuchinsky '142) — but no single cited reference anticipates any claim of US 5,158,319 under 35 U.S.C. § 102.

I'll ground the obviousness analysis by pulling the actual disclosures of the key prior-art references cited on the face of the '319 patent.

Let me pull the remaining cited references relevant to the folding frame and drum-wheel features.

Obviousness Analysis — US 5,158,319 under 35 U.S.C. § 103

Scope note up front: My final four searches (for US 298,784; DE 469,149; US 1,322,788; US 1,376,649) returned no results because I hit the tool-step limit. Those four references and US 66,861 are therefore treated below by title only, and I flag them as unverified. The five references I did retrieve in full (Roll Rite '919, Skelly '027, Bradov '396, Kuchinsky '142, Powell GB '717) carry the analysis.

1. Framework and level of ordinary skill

• Governing law: Application filed 1991-01-04 → pre-AIA § 103(a). The controlling obviousness standard is KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007): the TSM test is a helpful but not exclusive guide; a combination is obvious where (i) the claimed elements existed in the prior art, (ii) there was a known problem for which the combination was an obvious solution, and (iii) the results were predictable. MPEP 2143 rationales (A)–(G) apply.
• Level of ordinary skill (PHOSITA): a mechanical designer with ~2–3 years' experience in wheeled juvenile products (strollers, prams) plus general familiarity with hand carts, dollies and caster-equipped carriages — an art the '319 specification itself treats as unitary (it cites dollies, beach carts, container trucks and tractor vehicles on its face).
• Critical self-inflicted wound: The '319 specification admits much of the background: narrow hard wheels reduce contact area to reduce rolling friction on hard surfaces; swivelling small wheels dig in, oscillate and misalign on soft surfaces; rear-mounted handles load the front wheels. Admissions in the specification are prior art against the applicant. This narrows the "what did the inventor actually contribute?" question to essentially one thing: a mode-switching chassis that swaps a wide drum-wheel contact patch for a narrow swivelling contact patch.

2. The prior-art references and what they actually teach

3. Claim 1 — element-by-element mapping of the primary combination

Combination 1: Powell GB 2,223,717 + Roll Rite US 2,563,919 + Bradov US 3,173,396 + Skelly US 4,902,027 (+ applicant's admitted stroller art).

Assessment: claim 1 is, in my judgment, more likely than not obvious under § 103(a) as applied post-KSR. Every element is present, and the combination is a straight substitution of known elements with a predictable result.

4. Motivation to combine — the four strongest KSR rationales

1. The problem was known and stated in the art itself. Skelly '027 expressly identifies the exact dilemma: broad wheels are needed for sand/grass but "would make them so cumbersome as to detract from their usefulness on the usual even and solid terrain." A PHOSITA reading that sentence is being handed the design objective — keep both capabilities and switch between them — which is precisely the '319's stated object ("suitable for use on soft or rough surfaces" and "easily maneuvered on hard surfaces"). This is the classic situation where "the improvement is more than the predictable use of prior art elements according to their established functions" only if something unexpected results; here nothing does.
2. Roll Rite teaches the very mechanism, and teaches that it belongs on push/pull carriages. Roll Rite's stated object — intermediate non-swiveling wheels selectively engageable to disengage the casters at one end — is the '319 transition mechanism reduced to its function. Combining it with a baby carriage is the use of a known technique (selective auxiliary-wheel deployment) to improve a similar device (a hand-propelled carriage) in the same way. KSR, 550 U.S. at 417 (predictable use of prior art elements); MPEP 2143(A).
3. Powell puts the whole architecture on a stroller. Powell is not a container truck or a dolly — it is a foldable pushchair with an intermediate pivoting wheel-carrying axle, a detent lock, handle-operated release, castor steering, a seating pod, and a folding chassis. That is a one-reference teaching of the context into which Roll Rite's mechanism and Bradov's cylinders would be placed. Substituting wide cylinder wheels (Bradov) for Powell's small extra wheels and configuring the pivot stroke so the auxiliary wheel lifts a drum wheel is a design choice within a finite solution space, not an invention.
4. All-terrain capability was a recognized, active design trend. Skelly (1990), Powell (1990) and Kuchinsky (1987) all post-date/coincide with the commercial emergence of beach and jogging carriages, and all address sand/rough-terrain transport. A PHOSITA in the 1990–91 window had a strong, art-supplied reason to look at these references together.

Secondary rationales: (a) Obvious to try — the number of candidate configurations (raise the wide wheel / lower the small swivelling wheel, at the front, rear, or intermediate) is small and their performance predictable; (b) Rearrangement of parts — moving the hinge point of the intermediate member (claims 4, 7) is pure geometry; (c) Optimization of a result-effective variable — the width:diameter proportion of claim 10.

5. Remaining claims

6. Counterarguments a validity defense would raise (and my assessment)

1. The examiner already allowed claim 1 over all ten references of record. This is the single biggest practical problem with the attack above: it is built entirely from art already before the examiner. A § 103 challenge that merely re-argues the same references and adds no new teaching faces the examiner's implicit finding of no motivation to combine. To be litigation-grade, the attack needs new art. Two candidates surfaced in my searches (dates not fully verified):
   • EP 0 391 344 A3 ("Manually-propellable wheeled vehicle with obstacle-negotiating device"): a baby stroller with skids pivotally mounted and "releasably retained either (a) in a retracted, non-operative position… or (b) in an extended, operative position" — an express two-position, releasably-locked auxiliary ground-engaging member on a stroller (EPO PDF). If its publication predates 1991-01-04, it is powerful for the lock/config elements.
   • US 4,421,897 ("Variable terrain dolly," 1984) and US 4,618,157 ("Beach hand cart," 1986), both appearing in the "Similar Documents" list. I have not read them; they are cited only as leads.
2. Teaching away (Skelly). Skelly could be argued as teaching away from wide wheels generally. But Skelly's statement is a statement that wide wheels alone are unacceptable — it points toward a dual-mode solution, not away from one. And "teaching away" requires that the reference criticise, discredit or discourage the claimed solution; Skelly does none of the three for the combination. Defense-favourable nuance: a panel could read Powell as confined to kerb-climbing (an obstacle-negotiation function), not to terrain-mode switching, weakening the motivation link to Roll Rite.
3. Secondary considerations. None is in the record before me. No evidence of long-felt need, failure of others, or industry praise having a nexus to the claimed combination has been produced. The post-1992 commercial explosion in all-terrain/jogging strollers (e.g., the Graco "all-terrain stroller" designs in the Cited-By list) is temporally consistent with the patent but not shown to be because of it, and the patent was never asserted and lapsed in 2004 — which cuts against commercial-success evidence having been available to the patentee.
4. Claim 1's "substantially greater than is needed for rolling across a hard terrain surface" / "adapted for rolling across an unprepared soft terrain" is functional language that risks invalidity under § 112 rather than § 103; for § 103 purposes it must be read as covering any wheel wide enough to bear on sand, which is what Bradov and Skelly disclose.

7. Verdict

Bottom line: the '319 patent's contribution over the cited art is narrow — it is the placement of a known selectively-deployable auxiliary-wheel mechanism (Roll Rite) on a known articulated, detented, foldable pushchair chassis (Powell), using known wide soft-terrain rollers (Bradov/Skelly) with known annular traction rings (Kuchinsky) and a known pull handle (Roll Rite). Under KSR, that is a textbook predictable recombination. The honest caveat is procedural: every one of these references was before the examiner, so the art of record alone is unlikely to carry a formal invalidity holding without a new primary reference.

8. Flags and uncertainties

• Contradiction with earlier sections (must not be used): the earlier summary notes that US 2010/0066058 A1 ("All terrain stroller") cites and criticises the '319. That publication post-dates the 1991-01-04 priority date by ~19 years and is legally unusable as § 103 prior art against the '319. Its criticism of the '319's "gear-like ribs" and hand-operated raise/lower mechanism is useful only as commentary, never as an obviousness reference.
• Internal date inconsistency in the record: the current task states "Current Date: April 26, 2026," while the patent text supplied to me was fetched 2026-09-30. Immaterial to the § 103 analysis, but flagged per instructions.
• Unverified references: US 66,861, US 298,784, US 1,322,788, US 1,376,649 and DE 469,149 were not retrieved. Any reliance on them here rests on their titles/classifications alone; the Google-rendered titles for US 66,861 and US 1,322,788 are OCR-corrupted and I have not corrected them.
• EP 0 391 344 A3 date not confirmed. If its publication is after 1991-01-04 (or if it is not § 102(b)/§ 102(a) art), the strengthened attack in § 6.1 falls away.
• EP 1 481 871 ("Auxiliary device… standard pushchairs over sandy or similar surfaces") and the Stryker auxiliary-wheel patents (US 6,256,812) appear in the Citations/Cited-By lists but are post-1991 and unusable as prior art against '319.
• I did not obtain the '319 file wrapper; the examiner's reasons for allowance are unknown to me. If the applicant argued a specific unexpected result or criticality during prosecution, that could materially strengthen the non-obviousness position and I would need to revise § 7.