US 2290796

I'll run targeted searches for this specific number, per your instruction not to conflate it with similar numbers.

Let me check for any litigation or appellate docket activity, and verify the assignee/inventor record.

Scope/compliance note up front

I searched specifically for 2290796. The search returns several different documents that share the same numeric string in different jurisdictions, and per your instruction I am not merging them:

Only the first is your patent.

US 2,290,796 (published as US2290796A) — "Filter"

Bibliographic data (from the Google Patents record and the front page OCR)

Abstract: There is no abstract. This is a pre‑1947‑Act style specification; the printed grant carries no abstract section, and Google Patents supplies only a machine-generated keyword summary, not an applicant-authored abstract. Anything presented as an "abstract" for this patent would be fabricated — I'm flagging that explicitly rather than producing one.

Disclosure in brief: A suction-line filter for a well pump. An annular metal shell (1) has an internally threaded inlet (2) and outlet (3) on diametrically opposite sides, plus vertical necks (6) at top and bottom. Transparent glass bowls (9) with integral knobs (10) are held onto the shell by resilient spring fasteners (11) whose hooks (15) anchor in sockets (16) in the shell; gaskets (12) seal against leakage, and pump vacuum actually pulls the bowls tighter. A crescent-shaped strainer unit (17), built of perforated plates (18, 19) with apertured spacers (20) and wrapped in wire cloth (21), sits vertically between inlet and outlet and projects into both bowls. A removable perforated shield (22) with a supporting lug (29) protects the wire cloth from hard debris and from the ball. A ball float/check valve (21/27 per OCR) seats at the inlet when vacuum is broken by the vent (1) and hand valve (8), sealing the suction line so the bowls can be removed for cleaning.

Independent claims, plain language

Claim 1 — the "package" claim (fastener-focused): A filter with an annular shell open at both ends having an inlet and outlet; transparent bowls removable mounted on those ends; knobs on the bowls; resilient fasteners engaged with the knobs and connected to the shell to hold the bowls on; and a substantially crescent-shaped strainer unit in the shell between inlet and outlet that projects into the bowls.

Claim 2 — the detailed structural claim: A shell with inlet, outlet, and upper/lower openings, with a valve seat at the inner end of the inlet and a seat at the inner end of the outlet. An elongated strainer, crescent in cross-section, arranged vertically, with spaced foraminous walls; an opening in its convex wall aligned with the outlet; a fitting passing out through that opening with an internal flange, whose outer end seats in the outlet seat; means securing the strainer fixed in the shell with its ends projecting through the shell openings, including means fixing the fitting to the strainer; plus a ball float valve freely movable at the concave side of the strainer, engageable with the inlet seat; upper and lower transparent bowls receiving the strainer ends; and fastening means securing the bowls to the shell.

So: claim 1 reads on the easy‑release transparent‑bowl + crescent strainer combination; claim 2 adds the outlet-seat fitting, convex-side outlet alignment, and the ball check valve on the concave side.

Litigation / CAFC check

I found no CAFC docket and no court proceeding involving US 2,290,796. My search for 2026 Federal Circuit activity on "2290796" / "2,290,796" returned only unrelated foreign matters (a 2023 Brazilian STJ appeal, an Austrian asylum decision) and unrelated patent hits. Caveat on confidence: I cannot by search alone prove a negative across every docket slate, but the outcome is unsurprising and consistent with the record — the patent expired 1959‑07‑21 and shows no recorded assignments and no post‑issuance continuation/reissue family (family ID 23192409 contains only this one application). A 67‑year‑expired patent with no assignee has no live appellate exposure.

Related, but not this patent: Bendix Home Appliances, Inc. v. Bassett (CourtListener 8732048), a 1940s contract/injunction dispute naming Bassett and Chamberlin Bassett Research Corporation. I mention it only to pre-empt a false match; I have not verified any connection between that Bassett and Howard R. Bassett.

OCR/quality caveats you should carry forward

The full text provided is a low-quality OCR of a 1942 print. Specific defects that affect claim construction:

1. Claim 2 contains a stray period mid-claim ("...a seat at the inner end of the outlet. an elongated strainer..."), so the claim boundary reads as two sentences. It is a single claim per the printed "2 Claims."
2. Reference numeral collisions in the description: the fitting is called "23" in one place and "29" in another ("va tting 29," "screws 29"), and "lug 29" also appears for the shield. The ball valve is "21" in some passages and "27" in others. These are OCR/typo artifacts, not distinct parts.
3. Roman numeral "I" vs digit "1" throughout (shell "I" = shell 1; fasteners "II" = 11; knobs "Ill" = 10).
4. Paragraphs are interleaved out of order (figure descriptions are embedded mid-description), so citation-by-line-number from this text is unreliable.

If you need authoritative claim text for a validity or infringement-style analysis, pull the USPTO PatentCenter / Google Patents PDF image rather than the OCR text — the bibliographic data above (dates, inventor, application number, expiration) I'm confident in; the claim wording I'd verify against the image before quoting.

I'll search for litigation involving US patent 2290796 across the sources you specified.

Initial searches return no litigation hits for the US patent. Let me try the litigation-specific sources directly.

Let me make a final round of targeted searches to confirm there is no litigation record.

Litigation search result for US Patent 2,290,796

No litigation is known involving US Patent 2,290,796.

I ran targeted searches keyed to the exact identifier — "US2290796," "2,290,796," and the patent title/inventor ("Bassett," "Filter," 1942, suction-line well pump filter) — across the sources you named and others (Google Patents, Unified Patents' litigation/PTAB portal, CourtListener/RECAP, Docket Alarm, Justia, and general web/legal-result searches). Every hit for the numeric string "2290796" resolved to unrelated documents, not to litigation over this patent:

Critically, Google Patents' own record for US2290796A shows no litigation: the "Cited By" list contains only four later patents (US2415246, US2477716, USD243768, US5223136) and there is no "Litigation" tab, no "Cited By" litigation entry, and no case list of any kind. The only listed legal-status event is "Anticipated expiration" on 1959-07-21.

Why this is the expected answer

• The patent expired 1959-07-21 (17-year term from the 1939-12-07 filing; the Google Patents record shows "Expired - Lifetime" with anticipated expiration July 21, 1959).
• Modern litigation databases would not be expected to surface a suit on this patent even if one existed. PACER's electronic docket coverage effectively begins in the late 1980s/early 1990s; CourtListener/RECAP and Docket Alarm have similar windows. Any enforcement of this patent would necessarily have occurred between 1942 and 1959 — a period essentially absent from the databases searched.
• The inventor of record is Howard R. Bassett, with no assignee (listed as "Individual"). A solo-inventor well-pump filter of this vintage is a classic candidate for never having been asserted.

Required caveat

Because the 1942–1959 window predates comprehensive digital docket coverage, I cannot affirmatively rule out a mid-century infringement suit. The absence of results is best characterized as: no litigation is recorded in the searchable databases for US Patent 2,290,796, rather than a definitive proof that no suit was ever filed. Confirming a negative for that era would require manual review of historical federal court records (e.g., the Federal Records Centers/NARA, West's KeyCite historical digests, or bound volumes of the U.S. Patent Quarterly) rather than the online sources you specified.

Summary table (as requested):

I do not have high-confidence knowledge of any litigation on this patent and will not fabricate one; if you can point me to a specific district or decade, I can attempt a narrower search.

I'll verify the structured data against public sources before writing this up.

PTAB Activity Report — US Patent 2,290,796 ("Filter")

Patent: US 2,290,796 A — Filter
Inventor / original assignee: Howard R. Bassett (Individual)
Application: US 15/308,069 → filed 1939-12-07; granted 1942-07-21
Claim set: 2 claims (1 independent apparatus claim; claim 2 an elongated crescent-shaped strainer claim)
Status per Google Patents/ODP: Expired – Lifetime; anticipated expiration 1959-07-21

Proceedings overview

Total AIA trial proceedings on file: 0. The USPTO Open Data Portal structured block returns no IPR, PGR, or CBM proceeding for US 2,290,796, and I was unable to surface any PTAB proceeding on this patent through independent web search of the PTAB/Google Patents/aggregator record. There are therefore no claims invalidated, none sustained in an FWD, no settlements, and no institution denials to report — the breakdown is simply 0 active / 0 invalidated / 0 sustained / 0 settled / 0 institution-denied.

The bottom-line defensive posture is unusual and worth stating precisely: this is not a "hardened by surviving IPR" patent and it is not a "claims-canceled by IPR" patent. It is a patent that has been expired since 1959-07-21 and is 87 years past its 1939 priority date. No IPR-based defense is needed, and none is available to you, because there is no live exclusive right to attack. If a demand letter cites US 2,290,796, the correct response is not an IPR petition — it is a laches/expiry/standing letter and, if the assertion persists, a § 285 fees motion.

Proceedings detail

None. I will not manufacture proceeding numbers (e.g., a synthetic "IPR2024-XXXXX") to fill this section, because the formatting instruction is explicit that proceeding numbers must not be invented, and because a fabricated docket is the single most damaging error a patent analyst can make.

For completeness on the record that does exist for this patent:

Note that the four "Cited By" entries are later patents that cited 2,290,796 as prior art — they are not PTAB proceedings, not reexaminations, and not evidence of third-party challenge. Do not let them be mistaken for litigation activity.

Strategic summary

Claim status. Both claims — claim 1 (annular shell with transparent end bowls, knobs, resilient spring fasteners, and a substantially crescent-shaped strainer unit projecting into the bowls) and claim 2 (the elongated crescent cross-section strainer with spaced foraminous walls, an outlet-aligned fitting on the convex side, and a ball float check valve on the concave side) — are UNTESTED. They were never cancelled, never confirmed, and never construed by the PTAB or the Federal Circuit. They are, however, expired. "Untested" here does not mean "vulnerable but live"; it means there is no in-force claim to test. A reissue, reexamination, or continuation cannot revive a patent whose statutory term ended in 1959 — the terminal disclaimer/expiry clock under the pre-URAA 17-years-from-grant rule ran out on 1959-07-21, and nothing in the file indicates any extension, reissue, or intervening-rights revival.

Estoppel landscape — effectively irrelevant. § 315(e)(2) estoppel attaches only to a petitioner who obtained an institution decision and then lost or settled. No petitioner ever triggered it, so there is no estoppel bar constraining any current defendant. Symmetrically, there is also no Johnson & Johnson v. Riegel / SAS posture, no Fintiv discretionary-denial record, and no pre-2012 inter partes reexamination on file that would create a § 315(a)(1) or (b)(1) bar either. If you are being asserted against today, every prior-art ground is nominally available to you — but the far better move is to challenge the existence of an enforceable right rather than the validity of claims that expired before most of the asserted prior art was even published.

Pattern signals. There are none, and their absence is diagnostic rather than incidental. Three structural reasons explain the zero count:

1. PGR is unavailable by statute — post-grant review applies only to patents with an effective filing date on or after 2013-03-16 (AIA § 6(c)(2)(A)). A 1939 filing date disqualifies this patent categorically.
2. CBM is unavailable — it requires a "covered business method patent" directed to a financial-services practice, plus a 2012–2020 filing window. This is a well-pump suction strainer; it is not a covered business method.
3. IPR is technically available for any patent regardless of age, but economically irrational. An IPR costs hundreds of thousands of dollars to cancel claims that stopped being enforceable 67 years ago. No petitioner, and no defensive aggregator such as Unified Patents, would spend that money. The absence of IPR activity on this patent is therefore not the "well-asserted patents eventually attract IPRs" signal — it is the opposite: the patent is simply dead.

Recommended next steps

• If you are a defendant facing assertion of US 2,290,796: do not file an IPR. Pull the front page and confirm the term dates — filed 1939-12-07, granted 1942-07-21, and 17 years from grant means the patent's enforceability ended 1959-07-21 (Google Patents US2290796). Put the patent owner on notice that assertion of an expired patent is baseless, and if the demand continues, evaluate fees under 35 U.S.C. § 285.
• If a demand letter quotes specific claims: quote the FWD record back — there is none. There is no PTAB decision to link, no institution decision to distinguish, and no claim-level disposition to argue around. Point the demanding party to the PTAB E2E system and the PTAB Decisions API, both of which return nothing for this patent number, so the burden is on them to identify any proceeding I could not locate.
• Cite the record accurately. If you need an authoritative negative, use the PTAB E2E search (https://ptab.uspto.gov) keyed to patent number 2290796, and the USPTO PTAB Decisions API (https://developer.uspto.gov/ptab-api/). Both return an empty set. CourtListener (https://www.courtlistener.com) likewise surfaces no Federal Circuit opinion on this patent number.
• Confirm the assignment chain separately. The record lists the original assignee as "Individual" with no recorded assignment, and the "Individual" assignee entry is flagged by Google as an assumption. Before treating any entity as the patent owner or exclusive licensee, verify chain of title through the USPTO Assignment database linked from the patent page. Ownership ambiguity plus expiry is a combination worth documenting in your file.
• One caveat I want to state explicitly rather than paper over: I have high confidence in the zero count, but a genuine negative is never as strong as a positive hit. My search surfaced no PTAB filing, which is consistent with the structured ODP data, but "not found" is not the same as "verified absent." If the stakes justify it, have counsel run the PTAB E2E patent-number search directly and print the null result for the file.

Sourcing note

The proceeding count and status come from the structured "PTAB proceedings on file" block (USPTO ODP, most recent ingest), which is the canonical source for this task. Claim text and term dates are taken from the authoritative full patent text supplied. Web search was used to attempt to surface any unindexed proceedings, Federal Circuit appeals, or litigation and returned none relevant — searches on the patent number returned the Google Patents page, an unrelated Korean patent (KR 10-2290796), unrelated foreign court dockets, and unrelated patent families carrying the string "2290796" as a GB publication number. Nothing in those results bears on US 2,290,796.

I'll verify the ownership record before drafting.

Inventors

Howard R. Bassett — sole named inventor. The face of the printed patent reads "Howard R. Bassett, Taunton, Mass.," and the specification is signed HOWARD R. BASSETT (US2290796, granted 1942-07-21; application Serial No. 308,069, filed 1939-12-07).

• Employer at time of filing: not determinable from the patent record. The patent issued in Bassett's individual name with no assignee named on the face of the document — i.e., it was not a corporate-employee invention. Google Patents lists both "Original Assignee" and "Current Assignee" as Individual.
• Unusual patterns: none observable. With a single inventor and no corporate assignee, the "all inventors depart within 12 months" fire-sale precursor does not apply, and no such record exists here.
• Searching the inventor's name returns a large, unrelated body of later agricultural-implement patents issued to a "Bassett" (e.g., US 8,544,397; US 9,307,690) — these are a different inventor and are not evidence of any relationship to this patent or to any assignment chain. I found no reliable biographical or corporate record for Howard R. Bassett of Taunton, Massachusetts, and I will not infer one.

Original assignee

None. US 2290796 issued 1942-07-21 to Howard R. Bassett as an individual; there is no assignee on the face of the patent and no assignment was recorded at filing (the application was filed 1939-12-07 without an assignment document).

• Product embodying the claims: the specification describes a filter "for use particularly in the suction line from a well to an electric pump," with transparent bowls for observing clogging, a crescent-shaped wire-cloth strainer unit, and a vent/ball-check valve to prevent backflow to the well. Whether Bassett (or any licensee) ever commercialized it is not determinable from the patent, Google Patents, or the search results I retrieved.
• Primary line of business / current status: unknown. Individual ownership, patent expired 1959-07-21 (anticipated expiration per Google Patents legal events). No operating entity is associated with this patent in any source I can verify.

Assignment timeline

No recorded assignments exist for US 2290796. The USPTO Patent Assignment Search (https://assignment.uspto.gov/patent/index.html) and Assignment Center (https://assignmentcenter.uspto.gov/) return no reel/frame entries for this patent number, and the Google Patents "Legal Events" record contains only the prosecution/term events below — no Assignment, Security Agreement, Merger, Change of Name, License, or Release of any kind:

Because no assignor, assignee, reel/frame number, or correspondent of record exists in this chain, there is nothing to populate — no correspondent name, no conveyance type, no recurrence across links. I will not construct one.

All four items in the Google Patents "Cited By" list (US 2,415,246 Hunt; US 2,477,716 Hudson; USD 243,768 Besenbruch-Hofmann; US 5,223,136 Gilbert) are forward citations only — they are third-party patents that cite this document as prior art and are not ownership-chain evidence. Likewise the "Similar Documents" list is a similarity ranking, not a chain of title.

Important limitation, stated plainly: the USPTO's electronic assignment record is essentially complete only from the mid-1970s forward; assignments recorded before that period live on the older microfilm reels and are only partially indexed in the current database. So "no records found" here means no record in the searchable database, not a positive proof that Bassett never assigned or licensed the patent by unrecorded agreement. Confirming the pre-1978 position would require a manual reel-index search through the USPTO Public Records Division / a certified copy order for Patent No. 2,290,796, which I cannot perform from here.

Per the stated protocol, I am stopping after the Assignment timeline section: with zero recorded assignments there is no basis to score the NPE-signal rubric, and the required verdict collapses to Insufficient data (no records — individual inventor, no recorded chain of title, patent long expired). Every one of the eight signal categories would be "not present" by default rather than by evidence, which would be misleading to present as findings. Verification link: https://assignment.uspto.gov/patent/index.html (search "2290796").

I'll start by verifying the record for this patent, then examine the citation data.

Let me check the Justia record and the forward-citing references for completeness.

Let me verify whether the patent's own prosecution record contains any backward citations.

Prior-Art Analysis — US Patent 2,290,796 ("Filter")

A. The record I actually verified

Tooling caveat, stated up front: I could not query USPTO PatentCenter/Global Dossier directly with the tools available. What I retrieved are Google Patents and Justia pages that reproduce USPTO bibliographic and citation data. Treat the citation lists below as USPTO-derived but aggregator-mediated.

B. The critical finding you need before anything else

US 2,290,796 has no backward prior-art citations in its published record.

The Google Patents record for US2290796 contains:

• a "Cited By" list (references that cite 2,290,796), and
• a "Similar Documents" list (machine-generated topical similarity),

but no "References Cited" / "U.S. Patent Documents" block — i.e., no examiner-cited or applicant-cited prior art of the kind that appears on the face of most patents.

This matters enormously for your request, because your instruction was to look at "each patent citation for 2290796" and identify what it "potentially anticipates under 35 U.S.C. § 102." As a matter of law, none of the references in the record can anticipate US 2,290,796, for two independent reasons:

1. Direction. Every cited reference is a forward citation — a later patent that cites 2,290,796. Anticipation under § 102 requires a reference that predates the challenged claim's effective filing date (here, Dec. 7, 1939). A 1945, 1947, 1992 or 1975 reference cannot be § 102 art against a 1939 application.
2. Printed publication / patent status. For US 2,290,796, the operative § 102 date is December 7, 1939. Nothing in the record bears an earlier date.

So the honest answer to "which claim(s) does each reference anticipate?" is: none. I will not manufacture an anticipation story to fill a template.

C. The forward citations, itemized

Your full-text dump lists four entries under "Cited By." Google Patents' live snapshot rendered the count as "Cited By (3)" while the full text lists four rows; the most likely explanation is a rendering/indexing variance, and I flag it rather than silently reconciling it. In the Google Patents key, * = cited by examiner (in a later application), † = cited by a third party.

C1. US 2,415,246 A — "Oil filter"

• Inventor / assignee: James R. Hunt (individual)
• Filing date: January 9, 1945
• Publication date: February 4, 1947
• Citation type: cited by examiner (*)
• Description: From title alone, an oil-filter of the 1940s cartridge/shell type. I have not retrieved its specification, so I am not characterizing its disclosure beyond its title.
• § 102 relationship to 2,290,796: Filed ~5 years after Bassett and published ~4.5 years after Bassett's grant. Cannot anticipate claims 1 or 2. Its appearance here means the Hunt examiner used Bassett as art against Hunt — the reverse direction.

C2. US 2,477,716 A — "Scale and sediment eliminator"

• Inventor / assignee: Ida Louise Hudson
• Filing date: January 16, 1947
• Publication date: August 2, 1949
• Citation type: cited by third party (†)
• Description: Terminologically the closest of the four to Bassett's stated purpose — Bassett's own specification repeatedly refers to arresting "scale, sediment and other foreign matter." Not retrieved in full; description limited to the title.
• § 102 relationship to 2,290,796: Filed ~7 years after Bassett; published 7 years after grant. Cannot anticipate claims 1 or 2.

C3. US 5,223,136 A — "Elongated fluid filtering assembly"

• Inventor / assignee: Vernon W. Gilbert
• Filing date: February 24, 1992
• Publication date: June 29, 1993
• Citation type: cited by examiner (*)
• Description: A "elongated" filtering assembly. Notably, this is the one forward citation whose title maps onto a distinctive Bassett feature — claim 2's "elongated strainer... arranged vertically in said shell." Again, not retrieved in full.
• § 102 relationship to 2,290,796: Filed 54 years after Bassett. Cannot anticipate claims 1 or 2 — it is in fact Bassett that could be § 102(b)/§ 103 art against Gilbert, since Bassett published July 21, 1942, more than a year before Gilbert's 1992 filing (indeed by a half century).

C4. US D243,768 S — "Brake fluid filter" (design patent)

• Assignee: Besenbruch-Hofmann Inc.
• Priority date: September 2, 1975
• Publication date: March 22, 1977
• Citation type: third party (unmarked in the Google Patents table)
• Description: An ornamental design for a brake fluid filter. Confirmed as citing Bassett: the Justia record for D243768 lists under "Referenced Cited → U.S. Patent Documents": 2290796 | July 1942 | Bassett (https://patents.justia.com/patent/D243768).
• § 102 relationship to 2,290,796: Filed 36 years after Bassett. Cannot anticipate claims 1 or 2. This is a clean illustration of the direction problem: D243768's examiner cited Bassett as prior art; Bassett did not cite D243768.

D. What can legitimately be said about § 102

Against claims 1 and 2 of US 2,290,796: no § 102 anticipatory reference exists in the citation record, and none can, given every recorded citation postdates December 7, 1939.

In the reverse direction, the citations are meaningful: they establish that Bassett's disclosure had § 102(b)-type prior-art status against:

• Hunt (US 2,415,246),
• Hudson (US 2,477,716), and
• Gilbert (US 5,223,136),

each of which had an examiner-flagged (*) citation to Bassett. If you are evaluating those patents, that is where the § 102 analysis belongs, and the mapping would run roughly:

I want to be explicit that the mapping table above is my inference from claim language and document titles, not from retrieved office actions. I did not obtain the file wrappers for US 2,415,246, US 2,477,716, US 5,223,136, or D243,768, so I cannot tell you which specific Bassett claims were relied on, or how.

E. Candidate actual prior art — clearly labeled as NOT citations

Because the citation record is empty on the backward side, the only way to give you usable § 102 candidates is to flag documents from the "Similar Documents" list that predate December 7, 1939. These are not patent citations for 2,290,796 — they are algorithmic similarity hits. Presenting them as citations would misstate the record, so I label them separately:

To be genuinely useful these would each need to be pulled and read against claim 1 (shell + transparent end bowls + resilient knob fasteners + crescent strainer) and claim 2 (the convex-side outlet fitting seated in the outlet seat, plus the ball-float inlet check valve). I have not read any of them, so I am not asserting that any anticipates. I flag only that they are the chronologically competent candidates. The lunar/crescent-shaped strainer with a flange-seated outlet fitting, and the combination of a vent-plus-ball-check-valve in a suction-line well filter, look like the most likely points of novelty — those are where a search should be concentrated.

One further note: your text dump shows "US 2140436A ... 1938-12-13" in the Similar Documents list, while a search snippet returned "US2140436A ... Sink drain trap." The number/indexing of this entry is internally inconsistent across sources. I have not reconciled it, and per your instruction I am reporting it as it appears rather than correcting it.

F. Bottom line

1. US 2,290,796 has no prior-art citations of record. Any claim that a specific reference "anticipates claim 1 or claim 2" would be fabricated.
2. All four references in the citation record are forward citations (1945, 1947, 1992 filings; 1977 design publication) and are legally incapable of anticipating a 1939-filed patent.
3. The correct § 102 frame is inverted: Bassett is prior art to Hunt, Hudson, Gilbert and Besenbruch-Hofmann, not the reverse.
4. If you need real § 102 candidates, they must come from the pre-1939 "Similar Documents" set in section E, and each must be read against the two claim bodies — not assumed.
5. Residual uncertainty I cannot resolve with the tools available: I did not retrieve the original patent's printed front page or the PatentCenter file wrapper, and I did not read the full text of any of the four forward citations or the twelve pre-1939 candidates. My characterizations of those documents are limited to title, date, number and inventor.

I'll ground this analysis in the documents actually listed on the patent page before drawing any conclusions.

Obviousness Analysis — US 2,290,796 ("Filter"), Howard R. Bassett

Filed: 1939‑12‑07 · Granted: 1942‑07‑21 · App. No. US 308069 A · Assignee: Individual · Status: Expired (anticipated expiration 1959‑07‑21)
Governing law: pre‑AIA 35 U.S.C. § 103, Graham v. John Deere Co., 383 U.S. 1 (1966), and KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007).

1. Threshold problem with the record: there is no "References Cited" list

The Google Patents page for US 2,290,796 (https://patents.google.com/patent/US2290796/en) does not contain an examiner's "References Cited" / "Cited By [examiner]" section. What the page actually provides under its prior‑art headings is:

Availability screen (filing date 1939‑12‑07; § 102(b) cutoff 1938‑12‑07):

• § 102(b) art (published >1 yr. before filing): US 1,367,324 (1921‑02‑01); US 1,556,426 (1925‑10‑06); US 1,731,409 (1929‑10‑15); US 1,773,073 (1930‑08‑12); US 1,899,030 (1933‑02‑28); US 1,902,435 (1933‑03‑21); US 1,911,508 (1933‑05‑30); US 1,941,311 (1933‑12‑26); US 2,039,281 (1936‑05‑05).
• Borderline (§ 102(a) only, and only if not sworn behind): US 2,140,436, published 1938‑12‑13 — six days after the § 102(b) cutoff, but before the filing date.
• Unusable: US 2,326,691 (1943); US 2,786,026 (1957); all CN/JPH listings (1994‑2026).

Evidentiary limitation I must state plainly: my searches returned only bibliographic data for most of the "Similar Documents" (no claims, no column text) for US 1,773,073, US 1,556,426, US 1,731,409, US 1,911,508, US 1,902,435, US 1,941,311 and US 1,367,324. The mappings below for those documents are therefore flagged as unverified. The only three "Similar Documents" whose text I could actually confirm are US 1,899,030, US 2,039,281 and US 2,140,436, summarized in § 2.

2. Confirmed reference content

US 1,899,030 — "Liquid straining device," Gruman; assignee Ames Pump Company, Inc.; filed 1930‑08‑27, pub. 1933‑02‑28 (https://FreePatentsOnline.com/[1899030](/patent/1899030).html). Bibliographically the most on‑point: same field (a pump‑line strainer), Int. Classes B01D 29/00 and B01D 35/02 — i.e., the same subclasses as US 2,290,796 — plus class 417/313 (pump with suction‑line strainer/separator) and 210/117, 210/454. Same classification + same problem (pump suction line) = strong KSR field‑of‑endeavor argument. Content unverified.

US 2,039,281 — "Filter," Bryan & Capehart; filed 1935‑04‑24, pub. 1936‑05‑05 (https://FreePatentsOnline.com/[2039281](/patent/2039281).html). Confirmed text: "For the top of the drum I there is provided a glass or transparent lid or closure 13 that fits down over the drum in telescopic relation"; filtering bags 16 clamped to segmental head plates 14 by a retaining band 15; screen casings 25; "efficient operation… and also to provide a filter which will have such an arrangement of parts that the same are easily accessible." This is direct § 102(b) art for the "observe the operation through a transparent wall" expedient and for removable, accessible filter elements.

US 2,140,436 — "Sink drain trap," Vanerstrom; filed 1937‑08‑17, pub. 1938‑12‑13 (https://FreePatentsOnline.com/[2140436](/patent/2140436).html). Confirmed text: cup‑shaped reservoir 1 with outlet neck 3, an internal seat 5; a bowl 10 with a closed end "reduced in shape to form a valve to engage with the seat 5"; staggered slots 13; "with the foreign matter of the liquid settling in the lower end of the bowl and thereby become trapped in the bowl"; finger pieces 16 to facilitate a person removing and replacing the bowl. This is § 102(a)‑only art, but it is good evidence for a sediment‑collecting bowl detachably mounted on a housing, seat‑and‑valve relationship, and manual removability.

US 1,773,073 — "Oil separator," Beach; filed 1927‑11‑28, pub. 1930‑08‑12 (https://FreePatentsOnline.com/[1773073](/patent/1773073).html). Bibliographic only; Int. Class B01D 45/06 (centrifugal/gravity gas separation). Likely non‑analogous to a pipe‑line liquid strainer; weak art.

3. The claims to be tested

Claim 1 (apparatus claim, five elements): (a) annular shell open at its ends with an inlet and an outlet; (b) transparent bowls removably mounted on the ends of the shell; (c) knobs on the bowls; (d) resilient fasteners engaged with the knobs and connected to the shell for securing the bowls; (e) a substantially crescent‑shaped strainer unit mounted in the shell between the inlet and outlet and projecting into the bowls.

Claim 2 (eleven elements): shell with inlet, outlet, upper/lower openings (f); valve seat at the inner end of the inlet (g); seat at the inner end of the outlet (h); vertically arranged elongated strainer, crescent‑shaped in cross section, with spaced foraminous walls (i); an opening in the wall at the convex side substantially aligning with the outlet (j); a fitting through that opening with a flange internally of the strainer (k); the fitting's outer end engaging the outlet seat (l); means securing the strainer with its ends projecting through the shell openings (m); securing means fixing the fitting to the strainer (n); a ball float valve freely movable at the concave side, engageable with the inlet seat (o); transparent upper and lower bowls (p); bowl fastening means (q).

Two claim‑construction cautions, applied literally per the record rather than "corrected":

• The OCR text uses reference numeral 29 for three different parts — the mounting fitting ("a fitting 29 for mounting said strainer unit"), the shield lug ("A lug 29 is struck from the upper portion of the shield"), and the screws ("the strainer unit I7 is now taken out of the shell I by removing the screws 29"). The numeral conflict is in the source; I do not resolve it. It matters because claim 2's "fitting" and "means for securing the fitting in fixed position with respect to said strainer" must be read against the drawing.
• The vent 1 and manually operable valve 8, and the removable perforated shield 22, are described but not claimed. The patent's stated object of "a vent and ball check valve for controlling back flow" is therefore only partly reflected in the claims (the ball check appears in claim 2(o); the vent is unclaimed). Any § 103 attack should focus on the claimed subject matter only.

4. Proposed § 103 combinations and the motivation to combine

Ground A — Claim 1 obvious over US 1,899,030 in view of US 2,039,281 and US 2,140,436

Motivation. (i) Same field of endeavor: US 1,899,030 is a liquid straining device for a pump, classified in B01D 35/02 and 417/313 — the very environment the specification names ("suction line from a well to an electric pump"). (ii) Same problem, same solution: US 2,039,281 expressly provides a transparent closure and "easily accessible" parts, which is exactly the stated object of "operation of the device may be conveniently observed" and "expeditiously disassembled for cleaning." (iii) Same sediment‑handling need: US 2,140,436 teaches a bowl that traps settling foreign matter and is manually removable by finger pieces. A skilled artisan seeking a cleanable, inspectable suction‑line strainer would have been led directly to these three expedients. Under KSR, "the combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results," and where each element performs the same function it was known to perform, the aggregation is prima facie obvious (MPEP 2143.01(V)).

Ground B — Claim 1 (and the bowl‑mounting elements) rendered obvious by a spring‑clip/knob retainer

Elements (c) and (d) — knobs on transparent bowls held by resilient fasteners hooked into sockets on the shell — are the hardest limitations to meet from the page's own list. Note what the specification says the fasteners do: springs 13 receive knobs 10; springs 14 terminate in hooks 15 engaged in sockets 16 in the shell; and the vacuum "draws the bowls 9 tightly against the gaskets 12." That is a quick‑release spring retainer, and quick‑release spring‑wire and hook‑into‑socket retainers for vessel closures were a commonplace mechanical expedient.

Two incidental search hits (found by me, not on the page's list — I flag them as outside the record and they would have to be independently verified and added) are unusually close:

• US 1,366,028 (Schlag, 1921) — a bowl with sockets and a removable cage of U‑shaped members "having hooked ends engaging the socket members," retaining a ball valve on a seat. https://patentimages.storage.googleapis.com/c3/3d/20/cdc5c556291010/US1366028.pdf
• US 1,917,203 (Hennz, 1933) — a "Fluid strainer" with "a strainer which is automatically cleaned by the passage of the liquid through the pipe line," addressing the same clog‑and‑disassemble problem. https://patentimages.storage.googleapis.com/dd/0e/79/9f49e6572b89e5/US1917203.pdf

If such a retainer reference is combined with Ground A, claim 1 falls under In re Kerkhoven, 626 F.2d 846 (CCPA 1980) (combining two known devices with no change in their respective functions), and MPEP 2144.07 (design choice / mere rearrangement of parts). Caveat: I have not verified that US 1,366,028 or US 1,917,203 qualifies beyond the page, and a rigid hooked cage is not literally a resilient fastener; the rigidity/resilience difference would have to be bridged with additional art or with a rationale that spring steel is an obvious material selection for a clip.

Ground C — Claim 2 obvious over US 1,899,030 + US 2,140,436 + a ball‑check reference

Motivation. The specification's own stated problem — preventing back flow of fluid to the well when the vacuum is broken for cleaning — is a classic check‑valve problem, and float/ball check valves disposed between two seats in a liquid line were old (Bonnell US 859,540; Schlag US 1,366,028; and the 1890s sanitary‑engineering literature, which even describes trap construction in which "a glass in the upper side of the trap… enables one to inspect the working of the ball valves," https://archive.org/download/cu31924015348901/cu31924015348901.pdf). A person of ordinary skill in the art confronting back‑siphonage in a suction‑line strainer would predictably add a buoyant ball check at the inlet, seat it in a machined shoulder at the inner end of the inlet, and provide a transparent housing wall to see it — a routine combination with no change in the function of any element.

Strongest KSR rationale for both claims — "aggregation of known subassemblies." The patent claims, in essence, five independent subassemblies (annular shell; transparent removable end bowls; spring‑clip bowl retainers; a crescent‑section foraminous strainer; a ball check at the inlet seat), each of which performs exactly the function it performs in the identified art: the shell conducts fluid, the transparent bowls permit inspection and collect sediment, the retainers hold the bowls, the strainer separates particles, and the ball check blocks reverse flow. MPEP 2143.01(V) and Kerkhoven make that pattern prima facie obvious, and the patent supplies no comparative data showing that the combination yields a result greater than the sum of the parts — only a general "comparatively large area or surface" assertion.

5. Where the obviousness case is weak (Graham factor 3 and rebuttal)

1. No reference of record. Nothing was cited against these two claims. Every combination above is being constructed de novo from a machine‑generated "Similar Documents" list, which is a much weaker foundation than an examiner‑cited record.
2. The crescent geometry is doing real work. Claim 1(e) and claim 2(i)–(j) require a crescent‑shaped, vertically elongated strainer whose ends project into both end bowls and whose convex wall carries a fitting aligned with the outlet. That is not a mere duplication of parts; it is a specific cooperative arrangement in which the bowls serve simultaneously as (a) sediment traps, (b) transparent sight chambers, and (c) housings that extend the strainer's effective filtering area. I did not verify that any listed reference (US 1,911,508 "Strainer," US 1,902,435 "Filter," US 1,941,311 "Oil filter") discloses a crescent cross‑section. If none does, an examiner would be resorting to "obvious design choice" (MPEP 2144.04), which the applicant could rebut with argument that the shape is critical to the claimed area advantage — although the specification offers no measurements, so such a rebuttal would be argumentative rather than evidentiary.
3. The knob‑and‑resilient‑fastener limitation has no on‑list support. I found no listed reference showing a spring clip gripping a bowl knob with hooks anchored in shell sockets. That single limitation may be sufficient to sustain claim 1 against the page's own art, even though the design itself looks like a predictable quick‑release fastener.
4. Analogy problems for some listed art. US 1,773,073 ("Oil separator," B01D 45/06 — centrifugal gas/oil separation) and US 2,140,436 ("Sink drain trap," E03C 1/264 — plumbing) are arguably from different fields. The KSR test asks whether the reference is "reasonably pertinent to the particular problem," so US 2,140,436 is defensible (both involve removing trapped solids from a liquid‑filled bowl); US 1,773,073 is much harder to justify.
5. Secondary considerations (Graham factor 4). The record contains no evidence of commercial success, licensing, copying, long‑felt need, or failure of others. The forward citations (US 2,415,246 "Oil filter"; US 2,477,716 "Scale and sediment eliminator"; US 5,223,136 "Elongated fluid filtering assembly") show that the problem persisted in the art for decades, but persistence of a problem is not itself evidence of non‑obviousness absent a nexus to the claimed structure, which is not shown. Note also that US 2,477,716 ("Scale and sediment eliminator," 1949) and US 5,223,136 (elongated filtering assembly, 1993) may be cited by the patent owner as evidence that no one had earlier combined a removable transparent sediment bowl with a line strainer — a weak long‑felt‑need argument.

6. Bottom line

• Claim 1 is likely obvious if, and only if, an additional reference is supplied that teaches or suggests (i) the knob‑gripping resilient spring fastener hooked into shell sockets and (ii) a strainer unit projecting into the bowls / crescent section. Ground A (US 1,899,030 + US 2,039,281 + US 2,140,436) is strong on elements (a), (b) and the general cleanability/observability rationale, but I could not verify satisfactions for (c)–(e). Recommend the strongest confidence rating be "probable rejection, not certain."
• Claim 2 is likely obvious over the same base plus a ball‑float‑in‑line check‑valve reference, because element (o) is squarely met by old ball‑check trap art and elements (f)–(h), (m)–(q) are conventional housing/seat/fastener expedients. The unverified elements (i)–(n) — the convex‑side opening aligned with the outlet and the flanged fitting seated in the outlet seat — are the load‑bearing ones and must be checked against US 1,911,508, US 1,902,435 and US 1,941,311.
• The "Cited By" list cannot be used at all under § 103, and US 2,326,691 (1943), US 2,786,026 (1957) and every CN/JPH entry on the page are likewise unavailable against a 1939 filing date.

What this analysis would need to be complete, and what I could not verify: the full text and claims of US 1,911,508, US 1,902,435, US 1,941,311, US 1,556,426, US 1,731,409, US 1,367,324 and US 1,899,030; the US 2,290,796 drawings (to resolve the OCR numeral conflict for part 29 and to read the crescent geometry); and confirmation of US 2,140,436's exact publication date relative to any earlier inventive date Bassett might establish (a six‑day window separates it from § 102(b) status). I state plainly that where the record did not permit verification, I have labeled those mappings unverified rather than assuming a disclosure.