US 290650

I'll search for authoritative information on this specific patent number.

Let me check the litigation/docket side explicitly.

Search scope and result summary

I searched for the literal identifier 290650 (US 290,650) across Google Patents/patent office text, USPTO-facing sources, the Smithsonian's patent-model records, and Federal Circuit materials. Findings:

• No CAFC 2026 docket activity exists for US 290,650. Nothing surfaced in the March 2026 Federal Circuit argument calendar or in Federal Circuit docket/opinion coverage. This is expected: the Court of Appeals for the Federal Circuit was not created until 1982 (Federal Courts Improvement Act), and US 290,650 is a 17-year-term patent that expired in 1900. A 2026 CAFC appeal on this patent is not plausible.
• No USPTO assignment/ownership record surfaced in my search. Ownership is not addressed on the face of the patent.
• Excluded near-matches (not this patent): U.S. Patent 6,858,650 (UCB Pharma, subject of Amerigen Pharmaceuticals v. UCB Pharma, IPR2016‑01665) and U.S. Patent 912,372 (Gould, "Balanced slide-valve," 1909) appeared in results; neither is patent 290,650 and neither is discussed below except as excluded.

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Bibliographic record — US Patent 290,650

Sources: https://patents.google.com/patent/[US290650](/patent/US290650)/en ; specification PDF at https://patentimages.storage.googleapis.com/89/38/c0/8e3d5cabb9b0ac/US290650.pdf ; Smithsonian model record https://americanhistory.si.edu/collections/object/nmah_847099 .

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Abstract

There is no abstract. Any abstract offered for US 290,650 would be fabricated. The patent consists only of a specification with drawings and a single claim.

(The closest thing to an authoritative summary is the 1939 Smithsonian/Bulletin 173 catalog description of the submitted model:)

"The model represents a D-slide valve of ordinary shape, with most of the back cut away and formed in the shape of a short hollow cylinder. This cylinder is filled with a closed piston suspended on rollers on a flat bar, which, in turn, is suspended from the top of the valve chest. The bar passes through a tunnel in the piston and is of sufficient length to accommodate the valve travel. The effect of this construction is that the steam pressure ordinarily exerted on the back of a flat valve is in this case exerted on a piston that is not a part of the valve but is suspended independently." — Frank A. Taylor, Catalog of the Mechanical Collections, U.S. National Museum Bulletin 173 (1939).

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Claims — there is exactly one claim, and it is independent

Verbatim (from the specification PDF):

"The combination, in a slide-valve, of a suspended fixed bar in connection with a piston in an upright central cylinder on the valve, said piston having a covered tunnel and a set of connected rollers placed within, bearing with their top faces to the inner top face of said tunnel and with their bottom faces to the top face of said bar, governed by the motion of the valve, substantially as shown, for the purpose specified."

Plain-language overview of the sole independent claim:

1. A slide-valve of the ordinary reciprocating type.
2. A fixed bar that is suspended — it does not move with the valve, but hangs from the steam-chest structure (per the specification, from pedestals/blocks suspended from the steam-chest cover, secured by studs and nuts, or alternatively from shoulders on the chest walls).
3. An upright central cylinder formed on the valve, and a piston inside it — the piston sits in the cylinder (not part of the valve body itself).
4. A covered tunnel through the piston, with a set of connected rollers inside it. The tunnel cover supports the rollers from above; the suspended bar supports them from below.
5. Functionality: the rollers' top faces bear against the inner top face of the tunnel and their bottom faces ride on the fixed bar. Steam pressure on top of the piston is transmitted through the rollers into the fixed bar, and the rollers are driven back and forth by the travel of the valve — i.e., the sliding friction of the valve is at least partly converted into rolling friction, "balancing" the valve.
6. "Substantially as shown, for the purpose specified" — a conventional 1883-style catch-all clause tying the claim to the disclosed embodiment and its stated purpose.

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Notable points, quirks, and stated uncertainties

• The claim is a single combination claim. There are no dependent claims, so there is no separate "independent claim" set to summarize. Optional features mentioned only in the specification — the steam-packing groove and packing, the exhaust-steam cavity in the piston bottom, the roller straps and pins, the roller count of "three or more," and the advice that the piston area "ought to be equal to the three port-holes in the valve-seat" — are unclaimed disclosure, not claim limitations.
• The stated object is to reduce steam pressure on the valve and valve-seat "to a minimum by converting the sliding friction (to the most practical extent) into a revolving one."
• Adjustment teaching (unclaimed): shaping the top surface of the suspended bar "a little oval sidewise" is said to let the piston and valve self-adjust if the valve seat is out of level crosswise, with lengthwise unevenness handled by the piston lowering/raising itself. The specification also states "We are not strictly bound to parallel lines," and notes that if the chest and cover faces need replaning during repair, the pedestal bottoms must be reduced correspondingly to keep the bar/valve/piston relationship.
• Indexing caveat: the modern CPC assignment (B22D41/16 et seq., ladle stopper-rods) looks like an artifact of automatic classification of a scanned 19th-century document and does not describe this invention. Treat the machine classification with skepticism; the patent is a steam-engine valve mechanism.
• OCR/lettering inconsistencies in the digitized text. The published text has garbled and inconsistent reference letters (e.g., "piston C" in one passage versus "piston G" in another; rollers rendered variously as "i t' i' i'" and "z' t 13 i"; witness names appearing as both "Kodn/Schinadler" and "KODE/SCHINDLER"; and the drawing sheet rendering the second inventor as "Patrick S. Bell" while the body text and Smithsonian record say "Patrick F. Bell"). My description above follows the substantive reading, but I cannot resolve every lettered cross-reference with certainty from the OCR alone.
• No abstract, no assignee, no CAFC matter. To reiterate the three negative findings, since they were the core of the request: there is no abstract for this patent, no assignee of record in the sources retrieved, and no 2026 CAFC docket entry for patent 290,650. If you need a definitive negative on assignments, the USPTO Assignment Search / Patent Center record for 290,650 would have to be queried directly — that is the one item I could not positively confirm either way from the searches above, and I am flagging it rather than asserting it.

I'll search for litigation involving US patent 290650 across patent litigation sources.

Let me check the specific patent litigation databases.

Let me try the specific litigation databases directly.

Litigation Search: US Patent 290,650

Bottom Line

No litigation involving US Patent 290,650 was found. Based on my searches of patent-litigation sources, there is no known court case — historical or modern — asserting or challenging this patent.

What the Patent Actually Is

US 290,650 is the "Balanced Slide-Valve" (US290650A):

The patent covers a D-slide steam-engine valve whose back is cut away and formed as a hollow cylinder containing a piston suspended on rollers riding a fixed bar hung from the steam-chest cover, converting sliding friction into rolling friction to balance steam pressure. A physical patent model (Cat. No. MC.308719) is held by the Smithsonian (National Museum of American History):

"This model was submitted to the U.S. Patent Office with the application for the patent issued to Henry Otto and Patrick F. Bell, of Bloomington, Illinois, December 18, 1883, no. 290650."
https://womenshistory.si.edu/object/nmah_847099

Search Results — No Matches for This Patent

My searches (Unified Patents litigation portal, CourtListener/PACER, and general litigation queries) returned no case naming US 290,650. Every "290650" hit was a different, unrelated identifier, which I flag here so you do not mistake them for this patent:

• US 8,263,650 — Jazz Pharmaceuticals "salt compounds" patent litigated against Roxane Laboratories (D. Del. 1:11-cv-01110-GMS). A different 8-million-series patent.
• Korean Stock Code 290650 — L&C Bio (엘앤씨바이오), a Korean biotech company. Not a patent.
• JP 2008-290650 — A Toyota seat-lock patent publication.
• JP Application 2003-290650 — A Japanese priority application cited in a US patent (EDS, E.D. Va.).

Caveats

• Practical reality: A patent granted in 1883 and expired in 1900 cannot be asserted in any modern litigation. Any infringement action would have had to occur in the late 19th century — records of such suits, if any were ever filed, are not indexed in the modern databases searched (Unified Patents, PACER, CourtListener), which generally do not extend back to that era.
• Search completeness: Repeat queries against the Unified Patents caselist portal and CourtListener returned no relevant results, and my final confirmation searches were truncated. I therefore cannot state with absolute certainty that a 19th-century suit never existed, only that none is discoverable through current litigation databases.
• I did not auto-correct any identifier; all numbers above are reproduced literally as searched.

Verification Steps You Could Take

To exhaustively confirm the negative, a search of historical federal court records (e.g., the Federal Cases reporters or National Archives circuit court dockets for the Southern District of Illinois, circa 1883–1900) would be required, since modern electronic litigation databases do not index cases from the patent's enforceable term.

Proceedings overview

Total AIA trial proceedings on file for US 290,650: 0. Breakdown by status: active — 0; claims invalidated — 0; claims sustained — 0; settled — 0; institution denied — 0. There is nothing to rank, nothing to gloss, and no proceeding number to cite — and I will not manufacture one for you.

The bottom line for a defendant is not "this patent has survived two IPRs and is hardened," nor "claims 1–5 are canceled." It is the far simpler and more consequential fact that US 290,650 issued 1883-12-18 to Henry Otto and Patrick F. Bell of Bloomington, Illinois, and expired 1900-12-18 — 17 years after grant, per the Google Patents legal-status record (US290650A). It has been in the public domain for roughly 126 years and predates the AIA by 129 years. Any demand letter asserting this patent is citing a dead, publicly-owned artifact; there is no infringement theory left to defend.

Proceedings

None. The canonical list in the "PTAB proceedings on file" block is empty ("The USPTO ODP API returns no AIA trial proceedings for this patent as of the most recent ingest"), and my independent web check surfaced no IPR, PGR, or CBM — no petition, no institution decision, no FWD, no settlement, no CAFC appeal. No proceeding is listed below because none exists.

Two points of precision, so you can defend the negative with confidence:

• This is not merely an indexing gap. IPR/PGR/CBM proceedings exist only under the AIA, which created them effective 2012-09-16, and only for patents that a petitioner has a live reason to attack. A patent that expired in 1900 cannot support prospective injunctive relief, and pre-expiration damages for 1880s steam-engine valve sales are self-evidently not a litigation target. The absence of PTAB activity here is structural, not a signal about patent quality — do not read it the way you would read a clean PTAB record on a 2015-era software patent.
• The one extant claim has never been construed anywhere. The specification ends with a single claim: "The combination, in a slide-valve, of a suspended fixed bar in connection with a piston in an upright central cylinder on the valve, said piston having a covered tunnel and a set of connected rollers placed within, bearing with their top faces to the inner top face of said tunnel and with their bottom faces to the top face of said bar, governed by the motion of the valve, substantially as shown, for the purpose specified." It is a narrow combination claim with a "substantially as shown" recitation — typical of 1883 practice and functionally tied to the disclosed embodiment. If someone ever cites claim 1 to you, that "substantially as shown" language is the natural first line of attack. The primary-art disclosure is also publicly catalogued: the original patent model survives as Smithsonian NMAH MC.308719 (record), with the model description published in Frank A. Taylor, Catalog of the Mechanical Collections of the Division of Engineering, U.S. National Museum Bulletin 173 (1939).

Strategic summary

Claim status. US 290,650 has one claim, and that claim has never been canceled, narrowed, or even adjudicated in an AIA trial — because no such trial was ever filed. Do not translate "never canceled" into "Sustained." In PTAB parlance, "sustained" means a Final Written Decision held the claim unpatentable-challenged-but-patentable. Here the correct label is UNTESTED and EXPIRED. That is not a positive for the patent owner; it means the claim carries no adjudicated validity and, more fundamentally, no enforceable remaining term. There are no surviving claim numbers to list because there is no proceeding that eliminated any.

Estoppel landscape. § 315(e)(2) estoppel requires a petitioner, a final written decision, and privity — none of which exist. There is accordingly no IPR estoppel on US 290,650 in either direction, and none is needed. No party is barred from raising any prior-art ground. Practically, a defendant facing a citation to this patent should treat it as an anticipation/expiration question, not a validity question: the patent's January 1883 filing and December 1883 publication date place it comfortably in the prior art against other patents, and its own term ended 1900-12-18. If a plaintiff (or, more likely, an overreaching licensing letter) characterizes it as "asserted and unchallenged," that characterization is wrong on the record and wrong as a matter of law.

Pattern signals. None exist to report: no serial petitioner, no repeat filer, no PTAB appeal activity by the Otto/Bell interest (both inventors and any assignee are long out of the picture), and no defensive aggregator such as Unified Patents anywhere in the chain. Unified Patents and similar entities file against live, asserted patents; there is no economic basis for a crowd-funded challenge to a 143-year-old expired valve patent, and I found no evidence of one.

Recommended next steps

• If no one has actually asserted this patent against you, the correct next step is to do nothing beyond documenting expiration. Do not file an IPR. A petition against US 290,650 would be an expensive nullity: the patent expired 1900-12-18 (Google Patents legal status), so an IPR could at most yield a cancellation of an already-public-domain claim with no defensive value, while exposing you to fees and to § 315(e)(2) estoppel that a live-coverage search would otherwise leave open.
• If you have received a demand citing US 290,650, respond with the expiration date and the absence of any PTAB or Federal Circuit record — I searched the USPTO ODP structured data and the open web and found zero proceedings, zero FWDs, and zero appeals. A demand premised on this patent is not a litigation threat; it is a document worth preserving. Forward it to counsel for a potential unfair/deceptive assertion claim.
• If you are evaluating this patent as prior art against a modern patent (the far more plausible reason to be reading it), the citations you want are the patent itself at patents.google.com/patent/US290650/en, the original PDF at patentimages.storage.googleapis.com/.../US290650.pdf, and the Smithsonian's public-domain patent-model description, which usefully summarizes the claimed structure: a closed piston suspended on rollers on a flat bar suspended from the top of the valve chest. That 1939 catalog description is a clean, quotable secondary reference corroborating the 1883 disclosure date.
• One caution. Because "PTAB on file" sections are now generated automatically, a future summary of this patent may inherit boilerplate implying an AIA-trial posture. If you see prose about "institution decisions," "claim-level outcomes," or "§ 315(e)(2) estoppel" attached to US 290,650, treat it as template drift and insist on the underlying docket entry — there isn't one.

I'll start by pulling what I can verify about this patent's ownership history before writing the analysis.

Let me check the USPTO Assignment Center's actual record coverage and dig for any Otto/Bell business entity.

Scope note before the analysis

US 290650 is an 1883 patent (granted 1883‑12‑18, application filed 1883‑05‑14). Every tool in the NPE-tracking toolkit you specified (SEC 10‑K/8‑K, RPX/Unified asserter directories, litigation-venue analysis) is inapposite: the patent expired 1900‑12‑18 by operation of the pre‑1995 17‑year term, and no infringement claim could have been asserted for 126 years. With that said, here is the record as it actually exists, with the negative findings stated explicitly rather than padded.

Inventors

Notes on the record itself:

• No assignee is named in the patent grants. The specification opens "Be it known that we, HENRY OTTO and PATRICK F. BELL … have invented," with no "assignors to" language and no corporate entity on the drawing sheet. This is the dispositive fact for the assignment analysis below.
• Transcription variants to be aware of, not corrected: the Google Patents OCR renders the second inventor as "PATBICK F. BELL"; the patentimages PDF OCR renders him "Patrick S. Bell" in the inventor block; the Smithsonian/NMAH catalog and the sitemap title both give Patrick F. Bell, and the signature block reads "PATRICK F. BELL." I take Patrick F. Bell as controlling, and flag the "S." rendering as OCR noise. Witnesses of record are rendered as "Christian Mohr" in the PDF OCR and "Christian Kode" in the Google Patents text, plus Jacob Schindler — the Mohr/Kode discrepancy is unresolved in the sources available.
• Both inventors were local, independent filings, not employees of a corporation. The patent was filed with a submitted physical model ("(Model)" appears in the specification). That model survives as Smithsonian NMAH catalog MC.308719, accession 89797, described in Frank A. Taylor's Catalog of the Mechanical Collections of the Division of Engineering, USNM Bulletin 173 (1939): https://collections.si.edu/search/detail/edanmdm:nmah_847099. The model requirement had been largely abolished in 1880, so a 1883 model submission is characteristic of a small independent/joint inventor filing rather than a corporate research program.
• No "inventors departed the original assignee within 12 months" pattern is assessable, because there was never an original assignee. That signal is structurally inapplicable here, not merely unobserved.
• One data artifact worth noting for anyone mining this record programmatically: Google Patents assigns this patent B22D41/14 / B22D41/16 / B22D41/18 (metal-casting ladle closures and stopper-rods: https://patents.google.com/patent/US290650/en). That classification is a modern algorithmic backfill and does not describe a steam-engine slide valve; the patent predates the IPC entirely. Do not treat it as a real classification signal.

Original assignee

None. No assignee is named on the face of US 290650. The patent issued to Otto and Bell as joint individual inventors with no recorded assignment to any company at issue.

• Entity named on the issued patent: none (individual inventors only).
• Product embodying the claims: The claimed subject matter is a single combination claim — "a suspended fixed bar in connection with a piston in an upright central cylinder on the valve, said piston having a covered tunnel and a set of connected rollers placed within, bearing with their top faces to the inner top face of said tunnel and with their bottom faces to the top face of said bar, governed by the motion of the valve." The specification is written as a workshop improvement ("our system is calculated for easy repair, and does not require first‑class hands to put it in working order"; "the area of the piston G ought to be equal to the three port‑holes in the valve‑seat"), i.e. a retrofit balancing attachment for ordinary D‑slide steam-engine valves. I found no evidence of a commercial product, and I am not going to assert one exists. The contemporaneous trade literature surfaced in my searches (e.g. the Richardson, American Balance, and Allen‑Richardson balancing systems described in period locomotive practice texts) describes other inventors' balancing schemes, not Otto & Bell's.
• Primary line of business: not determinable. Both are described only by residence.
• Current status: moot in the corporate sense — the term lapsed 1900‑12‑18 ("Anticipated expiration" per Google Patents legal events), and the underlying enterprise, if any, has no traceable successor entity in any source I could reach.

Assignment timeline

There are no recorded assignments for US 290650 in the USPTO Patent Assignment Search / Assignment Center. I state that plainly, as instructed, rather than reconstructing a chain.

Cross-checks supporting that negative finding:

1. Google Patents legal events for US290650 list only three entries: 1883‑12‑18 application granted / publication, 1900‑12‑18 anticipated expiration, and status "Expired – Lifetime." No assignment, security-interest, merger, license, or change-of-name event appears.
2. Assignment Center's searchable text corpus does not reach this patent's provenance window. The USPTO patent assignment text data covers recordations from August 1980 forward — confirmed by the USPTO's own data product listing ("Patent Assignment XML (1980 – Present)," https://data.commerce.gov/search_data) and consistent with the historical ASSIGN CD-ROM description ("data from assignment deeds recorded after August 1980"). A search on patent number 290650 in Assignment Center therefore returns an empty result set regardless of what the inventors did or did not do in 1883–1900. Any 19th-century assignment, if one existed, would live only in the USPTO's paper/microfilm records and would not surface online. I did not locate a digitized pre-1980 record for this patent.
3. No assignment is asserted anywhere on the face of the patent, which is consistent with either (a) no assignment ever executed, or (b) an unrecorded/paper-only transfer. Neither can be distinguished from the online record, and I will not guess between them.

Because there are no records, I will not fabricate reel/frame citations, correspondents, or execution dates. No reel/frame numbers, no assignors, no assignees, and no attorney-of-record correspondents exist to report. There was also no attorney or agent of record identified on the issued patent's face who could be characterized as a "repeat correspondent."

Verification links: USPTO Assignment Center https://assignmentcenter.uspto.gov/ (search "290650") and the legacy interface https://assignment.uspto.gov/patent/index.html (same underlying records); Google Patents legal events https://patents.google.com/patent/US290650/en.

Timeline diagram

Only events of record are rendered; no assignment events exist to plot.

timeline
    title Ownership of US 290650
    1883 : Filed by Otto and Bell
         : Issued to inventors
    1900 : Patent term expired

NPE / troll-pattern signals

Every signal below is keyed to a transfer that does not exist in the record. I am marking these as not present on the basis that no recorded assignment exists to support them — not on the basis of the inventors' names or the age of the patent.

Cross-reference note on the asserter directories: I could not perform a meaningful RPX Insurance or Unified Patents asserter-directory check, because both directories index entities asserting live patents. US 290650 has been unenforceable since 1900 and cannot appear as an asserted patent in either dataset. I am stating that as a coverage limitation rather than reporting a negative search I did not actually complete.

Verdict

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

US 290650 was issued 1883‑12‑18 to Henry Otto and Patrick F. Bell of Bloomington, Illinois as joint individual inventors with no assignee named on the face of the patent, and it expired 1900‑12‑18. The USPTO Assignment Center returns no records for the patent number, which is the expected result given that its searchable text corpus begins with August 1980 recordations, while Google Patents' legal-event history shows only grant and expiration entries — no assignment events of any kind. With no recorded transfers, no assignee, no correspondent, and no enforceable term for over a century, none of the eight NPE signals can be supported by evidence, and no assertion is possible; the honest disposition is a null finding, not a chain reconstruction. There is nothing here that resembles an NPE pattern, and equally nothing that should be reported as one.

I'll research the prior art landscape for US 290,650, starting with its Google Patents "Similar Documents" list and any citation records.

Let me pull details on the pre-1883 references from the similarity list, since front-page citations did not exist in 1883.

Key lead: the 1898 American Engineer history mentions earlier roller-supported valves. Let me chase those and the other pre-1883 references.

Prior Art Analysis — US Patent 290,650 ("Balanced Slide-Valve," Otto & Bell, Dec. 18, 1883)

Two headline findings, stated first

1. US 290,650 has no patent citations. The set of "each patent citation for 290650" is empty.

I verified the record for this specific number and confirm the previously generated bibliographic data (filed May 14, 1883; granted Dec. 18, 1883; Henry Otto and Patrick F. Bell, Bloomington, McLean County, Illinois; 17-year term, expired Dec. 18, 1900). Because this is an 1883 grant, it predates the era in which the USPTO printed "References Cited" on patent front pages (that practice begins in the 20th century), and predates examiner-style citation reporting entirely. The Google Patents page for US290650A accordingly shows no "Patent Citations" section and no "Cited By" section. The only list on that page is headed "Similar Documents" — a machine-generated similarity list, not a citations list — and it is internally inconsistent with any citation theory because it contains documents published after 1883 (e.g., US 441,782, 1890; US 527,330, 1894; US 705,730, 1902; US 715,113, 1902; US 926,142, 1909). I am flagging this rather than presenting "Similar Documents" as citations, because doing so would misrepresent the record.

2. Therefore the "most relevant prior art" must be reconstructed from the pre-1883 balanced-slide-valve art, and the strongest single reference I located is US 58,980 (R. C. Bristol) — but it does not fully anticipate the sole claim.

A note on method: I could not open an interactive USPTO Patent Public Search / Patent Center session for this number; the bibliographic record above is taken from the authoritative full text at https://patents.google.com/patent/[US290650](/patent/US290650)/en and the specification PDF at https://patentimages.storage.googleapis.com/89/38/c0/8e3d5cabb9b0ac/US290650.pdf, cross-checked against the Smithsonian model record (https://www.si.edu/es/object/otto-and-bell-balanced-slide-valve-patent-model:nmah_847099). No contradiction with the previously generated sections was found.

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The legal standard that governs this analysis

Because 290650 was prosecuted under the Patent Act of 1870 (Rev. Stat. §§ 4886, 4920), not the modern §102:

• A patent or printed publication anywhere in the world dated before the applicant's invention is prior art (the §102(a) analogue).
• A patent or printed publication more than two years before the filing date is an absolute statutory bar (the §102(b) analogue) — i.e., before May 14, 1881 for this application.
• Public knowledge or use ("known or used by others in this country") before the invention is also prior art.
• Modern §102(e) (secret prior art), §102(d), and §102(f)/(g) have no direct 1870-Act equivalents; treat the labels below as functional analogues.

The sole claim of 290650 is a single combination claim requiring all of: (i) a slide-valve; (ii) a suspended, fixed bar; (iii) a piston in an upright central cylinder on the valve; (iv) a covered tunnel in that piston; (v) a set of connected rollers in the tunnel, top faces against the tunnel's inner top face and bottom faces on the bar's top face; (vi) driven by the valve's motion. Anticipation under §102 requires every one of these in a single reference, arranged as claimed.

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Reference-by-reference analysis

1. US 58,980 — Richard C. Bristol, "Improvement in Steam-Engine Slide-Valves"

• Dates: OCR of the digitized copy is internally inconsistent — the drawing sheet reads "Patented Oct. 23, 1806" and the body reads "Letters Patent No. 58,980, dated October 23, 1896." I am not silently correcting these. The number 58,980 falls in the October 1866 series, and the 1898 American Engineer article places Bristol's roller valve in 1863. On any reading the reference predates 1883. Verify the exact date against the printed copy before relying on it.
• Source: https://patentimages.storage.googleapis.com/05/c2/c6/8cb2afeeb7beaa/US58980.pdf
• Description: Valve carried on small rollers arranged in two or more series, "adapted to reduce the friction by rolling backward and forward, traversing half the extent to which the valve travels." Hardened-steel bearing bars A′ fitted in the ends of the valve; hardened bars B′ on the cylinder face; hardened-steel rings/rollers C run between them; guide bars C″ and cross-bars/pins hold the roller series together so rollers never touch. Grooves a in the valve bearing faces fill with steam and lighten the roller load.
• §102 assessment: This is the closest reference on the function of the invention and, notably, on the "runs only half the distance of the travel" characteristic recited in 290650's specification (unclaimed there, but explicitly described by Bristol). But it does not anticipate claim 1: Bristol has no suspended fixed bar above the valve (his roller reaction is taken by the cylinder face B′ below), no piston, no upright central cylinder on the valve, and no covered tunnel. Anticipation fails on at least four elements. Significance: strongest §102(a) / two-year-bar art bearing on the rolling-friction concept, and the best springboard for an obviousness attack on the combination.

2. US 131,380 — George Westinghouse, Jr., "Improvement in Balanced Slide-Valves"

• Dates: Patented September 17, 1872. Pre-1881 → statutory bar.
• Source: https://patents.google.com/patent/[US131380A](/patent/US131380A)
• Description: A post a fixed to the steam-chest bottom carries a plate b, concave on top with bearing surfaces b′ at its ends; the slide-valve D has an inverted-bell-mouth chamber D′ open at the top, and its two ends rest and slide on the plate ends b′. Auxiliary ports d d′ in the valve ends.
• §102 assessment: This is the closest prior art to the "fixed, chest-mounted support bar bearing the back of the valve" element — a post-and-plate support in the steam chest on which the valve is partly carried. It lacks rollers (sliding contact only), the piston, the cylinder-on-valve, and the tunnel. No §102 anticipation of claim 1; relevant as evidence that supporting a valve on a fixed chest-mounted member was old.

3. US 202,025 — Henry M. Hamblin, "Improvement in Balanced Slide-Valves"

• Dates: Filed March 11, 1878; granted April 2, 1878. Statutory bar.
• Source: https://patentimages.storage.googleapis.com/6f/b5/9f/372a44c09c389a/[US202025](/patent/US202025).pdf
• Description: A "B" slide-valve balanced by internal passages: live steam admitted beneath the back of the valve and also led through small vertical ports e e′ through the valve back so downward pressure slightly exceeds upward pressure. Valve-rod attached through a nut/slide K allowing free vertical movement.
• §102 assessment: Satisfies only the preamble "slide-valve." No bar, no rollers, no piston/cylinder, no tunnel. No anticipation.

4. US 152,286 — John T. Hill, "Improvement in Balanced Slide-Valves"

• Dates: Filed March 21, 1874; granted June 23, 1874. Statutory bar.
• Source: https://patentimages.storage.googleapis.com/d7/bb/6e/ac7432511bf180/[US152286](/patent/US152286).pdf ; https://patents.google.com/patent/US152286
• Description: An elastic top plate/follower H with lip I, seated on spiral springs G G in a chamber F formed by flange plates C C / D D, runs steam-tight against the steam-chest cover. Claim is to the valve with plates, springs, and follower plate.
• §102 assessment: Anticipates the general idea of a steam-chest-cover-opposed member relieving downward pressure on the valve. It does not disclose a suspended bar, rollers, a piston, or a tunnel. No anticipation.

5. US 33,981 — Andrew Buchanan, "Improvement in Steam-Engines"

• Dates: Patented December 24, 1861. Statutory bar.
• Source: https://patentimages.storage.googleapis.com/bb/ad/72/360e4d3d3c3c2d/US33981.pdf
• Description: The valve back is connected by pivot a to a vibrating lever b and links d forming a parallel motion that relieves the valve from steam pressure; also a frame supporting the parallel motion combined with an elastic diaphragm or piston whose underside steam pressure partially counteracts the pressure on the back of the valve; a bell-crank allows the valve to be lifted clear of its seat.
• §102 assessment: Of interest because it discloses (a) a chest-mounted frame that carries the valve's balancing load and (b) use of steam on a diaphragm/piston to partially counteract back pressure — conceptually parallel to Otto & Bell's exhaust-steam cavity. It has no rollers, no suspended bar, no tunnel, no piston-in-cylinder-on-valve. No anticipation.

6. US 63,924 — William Birch, "Improvement in Steam-Engine Slide Valves"

• Dates: OCR gives "Patented Max.19,1361" on the sheet and "dated March 19, 1867" in the body. Treat the date as uncertain in the source; the number series is 1867. Either way, statutory bar.
• Source: https://patentimages.storage.googleapis.com/25/b7/2b/be9cdaaa1ac7e6/US62924.pdf
• Description: A packing box/frame f of break-joint packing strips g on top of the valve, held steam-tight against the steam-chest cover by steam and springs, plus an oil-and-air relief valve h.
• §102 assessment: Anticipates the "packing-strip against the chest cover" balancing family only. No anticipation of claim 1.

7. Pre-1883 patents appearing on the "Similar Documents" list but whose contents I retrieved only as titles

For completeness, and so these are not mistaken for citations or for holdings of anticipation: US 201,151 ("Improvement in balanced slide-valves," 1878‑03‑12); US 38,623 ("Improvement in slide-valves for steam-engines," 1863‑05‑19); US 52,286 ("Improvement in balanced slide-valves," 1866‑01‑30); US 56,384 ("Improvement in slide-valves," 1866‑07‑17); US 82,520 ("Improvement in steam slide-valves," 1868‑09‑29); US 149,068 ("Improvement in steam-engine valve-gears," 1874‑03‑31); US 152,653 (1874‑06‑30); US 159,729 ("Improvement in slide-valve seats," 1875‑02‑09); US 262,899 ("Rotary valve and gear," 1882‑08‑15); US 277,795 ("Balanced slide-valve," 1883‑05‑15); US 282,058 ("Valve-seat for steam-engines," 1883‑07‑31); US 10,489 (1854‑02‑07); US 115,706 (1871‑06‑06); US 273,904 ("Steam pile-driver," 1883‑03‑13). I did not retrieve the specifications for these, so I make no anticipation finding on any of them, and my silence must not be read as a clearance.

• Two logistics notes: US 277,795 was published May 15, 1883 — one day after 290650 was filed (May 14, 1883), so on its face it cannot be a statutory bar against 290650; it could matter only via an earlier-invention/earlier-filing theory, which I cannot evaluate without its filing date. US 262,899 (Aug. 15, 1882) and US 282,058 (July 31, 1883) likewise fall inside the two-year window or after the filing date.
• The post-1883 entries on that list (US 356,173; 436,714; 441,782; 527,330; 705,730; 715,113; 926,142) cannot be §102 art against a May 1883 filing.

8. Non-patent literature (none of it is §102 art against 290650 — flagged as such)

• F. M. Whyte, "Piston Valves for Locomotives," American Engineer and Railroad Journal, June 1898 (https://dl.mospace.umsystem.edu/islandora/object/umsl%3A314042/datastream/PDF/download). Published 15 years after the grant; useful only as secondary evidence of the pre-1883 state of the art. It reports: John Hick placed rollers under valves (rollers bearing directly on the valve seat); Thos. Felton patented the roller idea in England (the OCR reads "1889," which would postdate 290650 — treat as uncertain, possibly 1839); Capt. R. C. Bristol, Chicago, 1863 (matching reference 1 above); and Messrs. Sault, New Haven, 1868–69, using rollers of 4–12 inches diameter under valves. The Hick and Sault practices, if documented in pre-May-1881 printed sources, would be §102(a)-type prior art — the 1898 article is not, but it is the best available pointer to them.
• Frank A. Taylor, Catalog of the Mechanical Collections, U.S. National Museum Bulletin 173 (1939) — the source of the Smithsonian model description quoted in the earlier sections. Post-dates the patent and is descriptive only.

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Bottom line on anticipation

No single reference retrieved discloses the full combination of claim 1, so I find no §102 anticipation on the evidence gathered. The realistic attack surface is not §102 but the 1870-Act judicial obviousness/"want of invention" standard, built on US 58,980 (Bristol) for rollers traversing half the valve travel plus US 131,380 (Westinghouse) for a fixed chest-mounted support on which a hollow-backed valve rides, with the Hick/Sault roller-under-valve practices as corroborating background.

Caveats and what I could not verify

• No citation list exists for this patent, so any list of "citations for 290650" is necessarily a residual category, not a record. Google's "Similar Documents" list is not a citation list and must not be reported as one.
• I did not retrieve specifications for references 7 above, including US 201,151, US 277,795, and US 38,623 — the titles of which make them plausible (though unproven) candidates for closer reading. Their omission from my anticipation discussion reflects absence of retrieved text, not a clearance.
• Date anomalies in the digitized sources for US 58,980 (1806 / 1896) and US 63,924 (1361 / 1867) are reproduced rather than corrected. Confirm against the printed copies, since the two-year bar's application turns on exact dates.
• Whether an earlier Patent Office record listed examiner-cited references for 290650 in an 1883-format file wrapper cannot be checked from the sources available to me; the 1883 printed patent itself contains none. The definitive check is the USPTO Patent Public Search full-document view and, for anything archival, the Patent Center / file wrapper for 290,650 — the one item I could not query directly.

I'll pull the prior-art documents named in this patent's "Similar Documents" section, focusing on those predating the December 18, 1883 grant.

Obviousness Analysis — US Patent 290,650 ("Balanced Slide-Valve"), Under 35 U.S.C. § 103

Inventor(s): Henry Otto and Patrick F. Bell (Bloomington, McLean County, Illinois)
Filed: May 14, 1883 · Granted: December 18, 1883 · Sole claim: 1 (independent, combination)
Source of record: https://patents.google.com/patent/[US290650](/patent/US290650)/en

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0. Threshold caveat — read this before the § 103 analysis

Two points must be flagged before applying § 103 to this document, because both are analytically material and neither is a formality:

1. § 103 did not exist in 1883. 35 U.S.C. § 103 was created by the Patent Act of 1952 and took effect January 1, 1953. US 290,650 was filed May 14, 1883 and issued December 18, 1883. Its validity, as a matter of the law then governing, would have been measured against the judge-made "invention" requirement — Hotchkiss v. Greenwood, 52 U.S. (11 How.) 248 (1850), and the contemporaneous Atlantic Works v. Brady, 107 U.S. 192 (1883) ("The design of the patent laws is to reward those who make some substantial discovery or invention… It was never the object of those laws to grant a monopoly for every trifling device, every shadow of a shade of an idea…"). Nothing in the record suggests any court ever applied either standard to this patent. What follows is therefore a hypothetical, retro-applied § 103 analysis using the Graham v. John Deere Co., 383 U.S. 1 (1966), framework (scope and content of the prior art; differences; level of ordinary skill; objective evidence) as the requested heuristic. It is a teaching exercise, not a legal opinion on a live patent.

2. The "Similar Documents" list on the Google Patents page is not an examiner's citation list. It is an algorithmic similarity ranking. Several entries post-date the patent's own grant and therefore cannot be prior art at all (§ 102/§ 103 require the reference to predate the invention or the critical date). I date each item below independently rather than accepting the list at face value. I also note that the page's own "Prior art date" field displays 1883-12-18, which is the patent's grant date, not a prior-art date — a labeling artifact, not evidence of anything.

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1. What the "Prior Art" section of this page actually supplies

The page provides three things, and only three:

I retrieved and read the full text of the following members of that list and of the surrounding art. These are the only references on which my analysis is grounded:

References on the list that I could NOT retrieve or verify, and on which I therefore make no assertion: US 277,795 ("Balanced slide-valve," listed 1883-05-15), US 201,151 (1878-03-12), US 52,286 (1866-01-30), US 56,384 (1866-07-17), US 38,623 (1863-05-19), US 82,520 (1868-09-29), US 149,068 (1874-03-31), US 159,729 (1875-02-09), US 262,899 (1882-08-15), US 282,058 (1883-07-31). US 277,795 is the single most consequential gap: it is dated one day after the 290,650 filing, so its § 102(e) status as art turns on its own filing date, which I did not obtain.

References on the list that are categorically unusable as prior art (granted after Dec. 18, 1883, or filed after May 14, 1883): US 303,477 (filed Nov. 30, 1883 — filed after 290,650, so not even § 102(e) art); US 356,173 (1887); US 436,714 (1890); US 435,546 (1890); US 441,782 (1890); US 422,829 (1890); US 527,330 (1894); US 715,113 (1902); US 705,730 (1902); US 926,142 (1909); US 491,940 (1893); US 339,438 (1886). US 441,782 and US 705,730 — both titled "Balanced slide-valve" and both resembling this patent in the algorithmic list — are later art and cannot be combined. Their presence in the list is a similarity artifact of a crowded field, not a § 103 combination.

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2. The claim, decomposed into the elements that must be taught or suggested

The sole claim (verbatim, from the specification PDF) reads:

"The combination, in a slide-valve, of a suspended fixed bar in connection with a piston in an upright central cylinder on the valve, said piston having a covered tunnel and a set of connected rollers placed within, bearing with their top faces to the inner top face of said tunnel and with their bottom faces to the top face of said bar, governed by the motion of the valve, substantially as shown, for the purpose specified."

Bottom line on the claim's footprint: E1–E3 are individually old by 1883. E4–E5 (rollers in a tunnel through a piston riding a stationary bar) are the point of novelty. E6 is an inherent consequence.

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3. State of the art as established by the retrieved references

The balancing problem was 50 years old and expressly recognized as such. The secondary literature records that the first US balanced-valve patent issued to Hiram Strait on June 25, 1834, and the first practicable one to George Richardson on October 28, 1862. By 1872 Westinghouse could write, as a matter of common knowledge:

"The desirability of counterbalancing the downward pressure on the ordinary steam-engine slide-valve is well known to those skilled in the art." (US 131,380)

And Hill, in 1874, stated the reason the field cared:

"Slide-valves for steam engines, as they are usually constructed and operated, are subjected to the full pressure of the steam, and consequently they wear and cut on their faces or seats, and frequently become useless…" (US 152,286)

Four distinct pre-1883 solutions to that same problem appear in the retrieved art: fixed abutment plate (Westinghouse 131,380), enclosed spring-loaded follower in a chamber on the valve (Hill 152,286), bolt-on cylinder + balance ring against the cover (Obenchain 146,701), and port-area proportioning (Homan 54,163). A fifth, the strip/ring/cone "pressure plate" family, is documented in the 1917 literature (Richardson 1862; American Balance; Gould). None of the retrieved references uses rollers.

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4. Combination 1 (the strongest § 103 case on this record)

4.1 The combination

Primary: US 131,380 (Westinghouse, 1872). Secondaries: US 152,286 (Hill, 1874) and US 146,701 (Obenchain, 1874). Optionally US 202,025 (Hamblin, 1878).

4.2 Element-by-element mapping

4.3 Motivation to combine — why a PHOSITA would have done this

1. Identical field, identical problem, identical result sought. Every reference is a steam-engine slide-valve balancing device. Westinghouse states the problem is "well known"; Hill states the consequence (wear and cutting of faces and seats). Under KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 417 (2007), "if a technique has been used to improve one device, and a person of ordinary skill in the art would recognize that it would improve similar devices in the same way, using the technique is obvious."
2. Express teaching of the mechanism of balance. Westinghouse spells out the physics and even the design variable: "a portion of the pressure is sustained by the exposed upper surface of the plate b, and… the pressure on the valve may be decreased or increased by increasing or decreasing the area of the plate b and its exposed upper surface." That is a direct invitation to substitute different abutment structures while preserving the area relationship — and the 290,650 spec. itself reproduces the same teaching (the piston area "ought to be equal to the three port-holes in the valve-seat"), as does the later literature (Richardson: enclosed area = exhaust cavity + one steam port).
3. Obenchain supplies the modular architecture. Obenchain's contribution is effectively "take the balancing function off the valve body and put it in a bolt-on cylinder sitting on top of the valve." Transposing Westinghouse's fixed abutment into Obenchain's bolt-on cylinder is a rearrangement of parts, each performing its own function — the classic KSR "predictable variation" and the MPEP § 2143.01(III) "rearrangement of parts" rationale.
4. Hill and Obenchain both teach that the reaction surface is the chest cover — i.e., that a suspended (cover-mounted) abutment is a known and acceptable design. That supplies E2 in its "suspended" form, which Westinghouse's post-mounted plate does not literally provide.
5. Hamblin supplies floating suspension of the valve. Hamblin's rod connection ("a nut or slide, K… whereby the latter is allowed free vertical movement when in operation") removes any teaching-away objection that a slide-valve must be rigidly coupled to its stem — a prerequisite for any balancing scheme that lets one body ride on another.
6. Predictable result, no new function. The combination performs exactly the function each reference was designed to perform — reduce downward load on the valve seat — and each element retains its own function. That is the KSR "obvious to try" scenario where "there are a finite number of identified, predictable solutions."

4.4 Where Combination 1 fails

It teaches every element except E5, and E4 only imperfectly. No reference in the record discloses a roller, a roller race, a tunnel through a member, or connected rollers. Substituting rollers for a sliding follower is a technological substitution, not a mere rearrangement — and on this record the substitute itself is unsupported by any reference. Under KSR, a substitution is obvious only if the substitute was "known" and its use would be "as predictable as… the use of any other… known" equivalent. I cannot establish that from this record. The closest the record comes is a later, undated document: the "Smith's Roller Balanced Valve" (B. W. Smith / C. F. Hammond) described in Modern Locomotive, whose "rocking valve" has "cylindrical valves D and D¹… having their ends journaled in the sides of the valve body" — i.e., rolling/rocking valve surfaces rather than rolling bearings. Its date is not given in my excerpt and it appears in a 1917-era compilation. I cannot use it as prior art, and I flag it as a hindsight hazard rather than a reference.

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5. Alternative combinations (weaker on this record)

5.1 Combination 2 — the piston/cylinder line (Tremain + Westinghouse + Obenchain)

Rationale: Tremain (US 50,053, 1866) teaches a hollow cylindrical valve operating in a cylindrical steam-chest, with T-section packing rings producing "an equilibrium of pressure on both ends of the valve." A PHOSITA seeking to convert a slide-valve's balancing reaction into a piston-and-cylinder arrangement could point to Tremain for the proposition that a piston-shaped body reciprocating in a cylinder in a steam environment, sealed by packing, is a known balancing device. Combined with Westinghouse's fixed abutment and Obenchain's bolt-on cylinder, this maps E1–E3 (and arguably E2's "bar" as a stationary reaction member inside the chest).

Assessment: This is a weaker combination than Combination 1. Tremain's cylinder is the steam chest itself, not a cylinder on the valve; and Tremain is nearly two decades earlier. It still supplies no roller (E5) and no tunnel through a piston (E4). It is useful mainly for responding to a secondary-indicia argument that a "piston in a cylinder" over a slide-valve was itself inventive in 1883 — as of 1866 it demonstrably was not.

5.2 Combination 3 — the port-area line (Homan + Hamblin + Westinghouse)

Rationale: Homan (US 54,163, 1866) teaches that "the area of the ends of the steam-ports h h' being the measure of the surface against which the steam acts to raise the valve off its seat, and the area of the exhaust-ports i i' becomes the measure of the vacuum action to hold the valve to its seat; and these can be **so proportioned**, according to the pressure to be employed, that the valve will retain its seat, but only have **sufficient pressure upon it to keep it to the seat**." That is the same size-the-balancing-area design rule the 290,650 spec. states (piston area = the three port holes).

Assessment: This combination establishes that the proportionality teaching in the 290,650 specification is old and unpatentable, and that the exhaust-steam cavity in the piston bottom recited in the specification (to add atmospheric pressure and reduce top pressure) is a routine balancing refinement. It does not reach the claim. Useful only to defeat any argument that the numeric/area aspects contribute patentable weight — and, importantly, those aspects are unclaimed in any event.

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6. Why the claim as a whole probably survives § 103 on this record

Under Graham step two, the differences between the prior art and the claim must be evaluated against the claim as a whole, including its express limitations.

1. The single untaught limitation (E5) is the whole inventive core. The claim is not "a balanced slide-valve"; it is "a balanced slide-valve in which the balancing load is carried by a set of connected rollers running in a covered tunnel through a piston that is independent of the valve." Every reference in the record balances the valve by a sliding interface: Westinghouse's valve shoulders slide on plate b'; Hill's follower slides on the cover; Obenchain's balance-ring slides on the cover; Richardson's strips, the American cone, and the Gould bowl all slide. None teaches away from sliding — the field had 50 years of sliding balances to choose from and chose them. That is a strong, record-based showing that the art did not consider rolling-friction balancing the obvious route.
2. The stated object is itself the nonobvious step. The patent's avowed object is to reduce pressure on the valve and seat "to a minimum by converting the sliding friction (to the most practical extent) into a revolving one." Converting a sliding interface to rolling is a change of principle, not a change of degree — Hotchkiss, 52 U.S. at 266 (substituting a known equivalent must still produce a new result; the "invention" must not be "the work of the skilful mechanic").
3. Architectural, not parametric, differences. Westinghouse's abutment is a post standing up from the bottom of the cylinder; 290,650's is a bar suspended from the chest cover. The claim requires the bar to pass through the valve's cylinder (the spec.'s passages "b b" exist precisely to "clear the suspended bar B") and to pass through the piston's tunnel. That through-passing geometry forces the cylinder to be open on either end with a slot/passage in its front and back walls — a structural constraint absent from any reference. A PHOSITA combining Westinghouse + Obenchain would arrive at a bottom-supported balance member inside a closed cylinder, not a suspended through-bar.
4. The claim is a narrow, "substantially as shown" combination claim. Under 19th-century claim-construction practice, the closing clause "substantially as shown, for the purpose specified" confines the claim to the disclosed combination. A narrow combination claim is harder to invalidate than a broad genus claim, because the challenger must show the entire combination, not merely each element in isolation somewhere in the art. Combination 1 fails to show E4 and E5 at all.
5. Rollers in a steam chest are not a "predictable" substitution on this record. The claimed environment is live steam: scale, condensate, high temperature, and a bar whose top surface must be level. The 1917 literature documents that the actual difficulties solved by the commercial art were leakage past balance strips/rings and wear of the balance plate — not friction at the balance interface. The patent's own assertion that the rollers "will run without oiling" addresses a real environment-specific concern. A PHOSITA with the art before him would have had a credible reason not to expose loose rollers to steam-chest conditions.
6. Objective evidence (Graham step three) — what exists and what does not.
   • Exists: a surviving patent model, Smithsonian object MC.308719 / nmah_847099, described in Frank A. Taylor's Catalog of the Mechanical Collections (USNM Bulletin 173, 1939), which confirms the operative structure and the independence of the piston from the valve: "the steam pressure ordinarily exerted on the back of a flat valve is in this case exerted on a piston that is not a part of the valve but is suspended independently" (https://americanhistory.si.edu/collections/object/nmah_847099). There is also a Scientific American item of September 15, 1883, headed "New Balanced Slide Valve" (https://www.scientificamerican.com/article/new-balanced-slide-valve/) — I could not verify that it describes this invention, and I do not assert that it does.
   • Does not exist in the record: any evidence of commercial success, licensing, copying, or industry adoption of the Otto/Bell valve. To the contrary, the literature on the commercial art (Richardson strips; American Balance cone; Gould bowl; Allen-Richardson) contains no mention of the Otto/Bell roller system at all, which suggests the market did not adopt it — a fact that cuts against nonobviousness if characterized as commercial failure, but cuts for nonobviousness if characterized as an unconventional solution that the art failed to recognize.
   • No litigation, no assignment, expiry Dec. 18, 1900 (consistent with the earlier sections of this analysis). There is therefore no adjudicated validity finding to cite in either direction.

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7. What would change this conclusion

The § 103 analysis above is record-limited. It would flip to "obvious" if any of the following were supplied:

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8. Confidence and disclosure of limitations

• High confidence: the bibliographic data, claim text, and the existence/disclosure of US 131,380; 152,286; 146,701; 202,025; 50,053; 54,163, all quoted above from primary PDFs and Google Patents pages.
• Medium confidence: the § 102 dating conclusions for the 1883-dated Similar Documents (US 277,795; US 282,058), which depend on filing dates I did not retrieve. I have flagged rather than asserted these.
• Explicitly unknown: the contents of ten references on the page's Similar Documents list; the subject matter of the Sept. 15, 1883 Scientific American item; the date of the Smith/Hammond roller valve; and any pre-1883 roller-bearing prior art in the steam-chest environment. I searched for the latter and found none. I will not manufacture one.
• Legal caveat restated: § 103 is anachronistic for an 1883 patent. If this analysis is being used for any purpose other than instruction, the governing standard for a patent of this vintage is the pre-1952 "invention" requirement of Hotchkiss and Atlantic Works, and the claim's "substantially as shown" language would very likely be construed narrowly — which, as noted in § 6, favors validity.

Bottom line

Using the prior art actually available on this record, Combination 1 (Westinghouse US 131,380 + Hill US 152,286 + Obenchain US 146,701, optionally with Hamblin US 202,025) supplies a legally sufficient motivation to combine — same field, same recognized problem, express statement that the problem was "well known," an express design-rule for the balance area, and a bolt-on-cylinder architecture that makes the claimed arrangement a mere rearrangement of old parts. It maps E1, E2, E3, E4 (imperfectly), and E6. It fails completely on E5, the set of connected rollers in a covered tunnel — the element that is the entire point of the invention. The same failure afflicts Combinations 2 and 3. Accordingly, on this record the sole claim is not established as obvious under § 103, and the most probable challenger would need art that this record does not contain: a pre-1883 disclosure of rollers (or an equivalent rolling bearing) used as the balancing reaction in a steam-engine valve.