US 315550

I'll run the requested database checks before summarizing.

Search results (as requested, restricted to 315550)

Queries run: US patent 315550 Renchard Lubricator 1885 and "315,550" patent CAFC 2026 docket.

• USPTO / Google Patents record for US 315,550: retrieved in full and used as the authoritative source.
• CAFC 2026 dockets: no 2026 (or any modern) Federal Circuit docket, appeal, IPR, or PTAB proceeding referencing patent 315,550 was found. Absence of a result here means only that no such record surfaced; it is not affirmative proof that none exists in an offline index.
• Closest returned item on the second query was a 2026 NYIPLA/PTAB committee report listing unrelated IPR numbers (IPR2025‑01451, IPR2026‑00058, etc.) — noise, not a match on 315550.
• Family/litigation context found was 19th‑century: Detroit Lubricator Manuf'g Co. v. Renchard (CourtListener op. 8341027), which concerns a Parshall patent and Renchard's earlier patent 184,426 — see the uncertainty note below. It is not a record of litigation of 315,550 itself.
• Sibling check: I did not substitute results for the similar number 315,551 (also "Lubricator," F. J. Renchard, Apr. 14, 1885, per DATAMP). I flag it only so you know the two were not conflated.

Summary of US 315,550

Abstract

Patents of this era carried no formal abstract. The specification opens with the closest equivalent:

"My invention belongs to that class of lubricators in which the oil is caused to rise in visible quantities through water contained in a transparent tube by means of the action of water, the product of condensation, which displaces the oil in a reservoir connected with said transparent tube."

The stated inventive core: placing the oil reservoir inside an enclosing water chamber whose water is the direct condensate of steam admitted to it, so that heat keeps the oil fluid; plus particular arrangements of the integral parts.

Plain-language overview of the independent claims

All five claims are drafted in 1885 combination style using reference letters (A, B, D, E, I, J…). Claim 1 is unambiguously independent. Claims 2, 3, and 4 recite combinations of previously described elements but contain no "as claimed in claim 1" back‑reference, so formally they read as separate combination claims rather than dependents; claim 5 is independent and deliberately broad. Claim 5's text in the OCR is garbled where it runs into the signature block — the reconstruction below is my best reading.

Claim 1 — Oil chamber nested in a steam/water jacket, plus a sight glass.
A lubricator with an oil chamber surrounded and enclosed by an outer chamber for water and steam, combined with a transparent tube through which the oil passes "in visible quantities" on its way from the oil chamber to the part being lubricated. This is the broad conceptual claim: jacketed oil reservoir + visible drip feed.

Claim 2 — Jacketed chambers + regulating water valve + oil take-off tube.
In combination with interior oil chamber B: exterior water/steam chamber A, valve D admitting water from A into B in regulated quantities, and a tube discharging oil from the upper part of the oil chamber as water is introduced at the bottom of the oil. Essentially: a displacement‑type lubricator, with the water admitted low and the oil drawn off high.

Claim 3 — The concentric valve assembly.
In combination with exterior and interior chambers A and B: the tubular regulating valve D establishing communication between them, and the central valve E for exhausting the contents of the inner chamber through the outer chamber. In other words, a drain (drip) valve nested inside the regulating valve, so the water can be let out of the oil chamber without a separate port.

Claim 4 — The indicator subassembly.
The combination of outer chamber A, inner chamber B, glass holders I, I′, the intermediate indicating glass J, and the induction and discharge pipes (t″/t′). A structural claim to the sight‑glass feed-and-discharge arrangement as built into the outer wall of the water chamber.

Claim 5 — Broad functional claim (same plane, single partition).
A lubricator combining, in its construction, an oil chamber and a steam-and-water chamber arranged in the same plane and separated by a single partition through which heat is transmitted from the steam/water to the oil, together with valves and pipes delivering water to the oil chamber in regulated quantities to displace the oil. This is the broadest read on the heat-transfer relationship itself, written to avoid being limited to concentric cylinders.

How the device works (one paragraph)

The unit screws into an engine steam pipe via tubular extension C. Steam enters outer chamber A through space L and condenses there, filling A with hot water. Opening regulating valve D lets that water into the bottom of oil chamber B, lifting the oil out through vertical pipe m into the water‑filled indicator glass J, where the oil rises drop by drop and is visible; it then passes check valve H into tube t, tube t′, pipe N, and finally into the steam pipe (or cylinder). When the oil is exhausted, valve D is closed and drip valve E opened to drain the water from B; E is then closed, B is refilled with oil, and feeding resumes on reopening D. The oil stays fluid because chamber B is exposed to the heat of the steam and water surrounding it in A.

Uncertainty / caveats

• Assignee: no assignee is stated in the patent text or the Google Patents record. I cannot supply one without fabricating it. The 19th‑century Renchard/Parshall lubricator litigation involved the Detroit Lubricator Manufacturing Co., but the opinion found relates to a different patent (Parshall's) and to Renchard's 184,426 — it does not establish ownership of 315,550. Treat any assignee attribution as unverified.
• Claims 2–4 as "independent": this is a formal reading of the claim language, not an authoritative USPTO dependency determination.
• Litigation: I found no modern (including 2026) litigation, IPR, or CAFC docket activity for 315,550. The patent expired April 14, 1902 and has been public domain for well over a century.
• Text corruption: the OCR of the original print is imperfect (e.g., "iuidity" for "fluidity," "i" for "t" in pipe labels, mangled claim 5). Claim interpretations above are reconstructions grounded in the specification.

Sources

• https://patents.google.com/patent/[US315550](/patent/US315550)/en (authoritative full text and bibliographic data)
• https://www.courtlistener.com/opinion/8341027/detroit-lubricator-manufg-co-v-renchard/ (family/technology context only)
• https://www.datamp.org//patents/search/xrefClass.php?source=xrefClass184-51 (classification cross-reference; note the listing surfaced 315,551, not 315,550)

I'll search for litigation involving US patent 315550.

The first search returned an unrelated modern "'550 Patent" (a 2018 tarpaulin storage-system patent). Let me verify more specifically.

Let me run a few more targeted checks before concluding.

Bottom line

No litigation involving U.S. Patent No. 315,550 could be identified. I found no district court action, circuit court action, appellate decision, PTAB proceeding, ITC investigation, or reported opinion anywhere that asserts, tests, or otherwise involves US 315,550 — either by its literal number or by its subject matter in an enforcement posture.

Why the answer is "none"

1. The patent has been dead for over a century. US 315,550 ("Lubricator," Francis J. Renchard, Detroit, Michigan) was filed November 10, 1884, granted April 14, 1885, and the Google Patents record lists an anticipated expiration of 1902-04-14 (the then-applicable 17-year term from grant). Legal status: "Expired – Lifetime." Any cause of action on the patent itself had to be brought between April 1885 and April 1902.

2. No modern forum could have a case on it. PTAB/IPR, Unified Patents' litigation and PTAB caselists, PACER and CAFC dockets are structured around post-1980 practice. Nothing in those databases keys to a six-digit 1885 patent number.

3. Google Patents' own cited-by/similarity data contains no litigation. The only "Cited By" entry is EP0421229A1 (General Electric, creep/stress-rupture alloys, 1991) — a classification artifact with no litigation significance. The "Similar Documents" list is a set of other 19th-century lubricator patents (e.g., US273312, US315551, US250944, US312973, US228216, US293590, US191171), which are prior art/neighbors, not lawsuits.

False positives I rejected (strict literal-number discipline)

Every search hit for "550" was a different patent or number. I did not substitute these for 315,550:

Adjacent history worth distinguishing (same field, same family — but NOT this patent)

Because the inventor's surname and the lubricator art recur in 19th-century reports, these are often mistaken for 315,550 litigation. None involves US 315,550:

• Detroit Lubricator Manuf'g Co. v. Renchard, 9 F. 395 (C.C.E.D. Mich. 1881) — Plaintiff sued as assignee of Charles H. Parshall, Patent No. 191,171 (May 22, 1877); defendants J. Vincent Renchard and John J. Renchard defended under their own Patent No. 184,426 (Nov. 14, 1876) and alleged Parshall obtained the invention surreptitiously. Decree for complainant on claim 6. (Filed May 4, 1881 — four years before 315,550 issued.)
• Tucker v. Sargent, 9 F. 289 (C.C.D. Conn., Sept. 2, 1881) — Parshall Patent No. 191,171; complainant's decree granted. Again pre-1885.
• Jenks v. Swift, 25 F. 722 (C.C.N.D.N.Y., Nov. 26, 1885) — Clark Patent No. 187,964 (Mar. 6, 1877); claim 2 construed narrowly and held not infringed. Same art, different patent.
• Note also that the Renchard brothers' earlier patent 184,426 is the reference cited in these opinions — not 315,550.

I also encountered a citation, Renchard v. Humphreys & Harding (reported at 59 F.R.D. 530), in citation indexes. I could not verify its subject matter from the available results, and nothing in the retrieved material links it to US 315,550. I flag it only so the name coincidence is not mistaken for a connection; do not treat it as litigation on this patent on the strength of this report.

Confidence and caveats

• High confidence that no litigation on US 315,550 is recorded in modern patent-litigation databases, because such databases cannot and do not index a patent that expired in 1902.
• Moderate confidence that no 1885–1902 infringement suit on 315,550 exists at all. Full-text coverage of late-19th-century circuit court opinions is good but not exhaustive (many were unreported or reported only in the Official Gazette), and I was unable to complete follow-up searches of CourtListener, the Off. Gaz. digest, or the Federal Reporter digests before exhausting my search budget.
• Recommendation if you need a definitive negative: have a searcher run the literal string 315,550 and 315550 across the Federal Reporter (1st series, vols. 23–120, covering 1885–1902), the Official Gazette patent-suit digests, and the Decisions of the Commissioner of Patents for those years. Renchard's assignees, if any, would most likely appear as complainants in the C.C.E.D. Mich. or C.C.N.D.N.Y.

No case name, docket number, court, filing date, or outcome can be reported for US 315,550, because no such case exists in the record I could retrieve.

I'll verify the structured data against live sources before writing anything up.

PTAB Activity Report — US Patent 315,550 ("Lubricator")

Patent: US 315,550 — Lubricator — Francis J. Renchard, Detroit, Michigan
Application filed: 1884-11-10 · Granted: 1885-04-14 · Anticipated expiration: 1902-04-14
Source of record: https://patents.google.com/patent/[US315550](/patent/US315550)/en

Proceedings overview

Total AIA trial proceedings on file: 0 (0 active, 0 claims-invalidated, 0 claims-sustained, 0 settled, 0 institution-denied). The USPTO Open Data Portal returns no AIA trial proceedings for this patent, and independent web searching surfaces no IPR, PGR, or CBM naming US 315,550 as the challenged patent. The bottom-line defensive posture is not "hardened patent" or "claims canceled" — it is "this patent has been expired since 1902-04-14 and cannot be asserted at all." A demand letter citing US 315,550 is not a licensing opportunity; it is a signal that the sender has not run a basic patent-status check.

Notes on verification: AIA trials (§§ 311–329) did not exist until the Leahy-Smith America Invents Act took effect on 2012-09-16. This patent expired roughly 110 years earlier. Even setting that aside, a search across PTAB dockets, PTAB E2E, and general web sources returns no trial proceeding of any type against this patent number. I found no Federal Circuit appeal, no settlement, no institution decision, and no judge panel, because there is no proceeding to report.

One caveat worth flagging as a data artifact, not a real citation: the Google Patents "Cited By" field for US315550 lists EP0421229A1 (General Electric, "Creep, stress rupture and hold-time fatigue crack resistant alloys," priority 1989-10-04). A 1991 metallurgy application does not cite an 1885 steam-engine lubricator. Treat that field as a harvesting error rather than evidence of a live family or continuation chain.

Per-proceeding detail

None. There are no proceedings to enumerate. I am not going to manufacture docket numbers, panels, or dispositions to fill this section — doing so would be exactly the failure mode this report exists to prevent.

What I can report instead is the claim-level status, which is unambiguous:

No claim is canceled. No claim was held patentable in an FWD. No claim was construed by the Board. "Untested" here does not mean "vulnerable" — it means the claims left the enforceable universe in the McKinley administration.

Strategic summary

Canceled vs. sustained vs. untested. The framing does not apply. Nothing was canceled by the PTAB and nothing was sustained; the entire patent lapsed by operation of the pre-1995 seventeen-year term, 17 years after the 1885-04-14 grant. All of claims 1–5 are expired. Under 35 U.S.C. § 271, infringement requires an unexpired patent — there is no act of infringement of US 315,550 possible today. The specification's own fallback language (the paragraph beginning "I have illustrated my invention in what I consider its best embodiment; but it is evident that considerable variations may be made in details") shows Renchard himself treating the claims as a negotiated set of combinations, but that is of historical interest only.

Estoppel landscape — § 315(e)(2). There is no estoppel, because there is no petitioner and no final written decision. Section 315(e)(2) estoppel attaches only to a petitioner that obtains an FWD, and it bars that petitioner and its privies from raising grounds it raised or reasonably could have raised. With zero proceedings, no prior-art ground is foreclosed to anyone — but no defendant needs one, since invalidity is moot when the patent is unenforceable for expiration. If you want the short answer for a client facing assertion: you do not need prior art. You need a printout of the face of the patent.

Pattern signals. No petitioner has filed serially, no patent owner has appealed anything to the Federal Circuit, and there is no defensive aggregator (Unified Patents or similar) in the chain. The absence of PTAB activity is not the usual "conservative patent owner, nobody bothered" signal — it is the opposite: the patent was never a candidate for IPR because it was 127 years expired when IPR became available.

Historical context (the real "litigation history" for this patent family). This patent sits inside a genuinely litigated 19th-century lubricator family worth knowing about if the patent number ever appears in a chain-of-title or prior-art argument:

• Detroit Lubricator Manuf'g Co. v. Renchard, C.C.E.D. Mich. (1881) — construing Charles H. Parshall's patent No. 191,171 against the Renchards' earlier patent No. 184,426, and addressing the "directly secured" limitation on the condensing/oil chambers. Full text: https://www.courtlistener.com/opinion/[8341027](/patent/8341027)/detroit-lubricator-manufg-co-v-renchard/
• Jenks v. Swift, 25 F. 722 (C.C.N.D.N.Y. 1885) — limiting William A. Clark's patent No. 187,964 to a drip-tube delivering drops against the side of the glass. https://law.resource.org/pub/us/case/reporter/F/0025/0025.f.0722.pdf
• Sibling/same-day filing US 315,551 (F. J. Renchard, 1885-04-14) and US 264,476 (John J. Renchard, 1882-09-19) cover related displacement-lubricator subject matter.

These are district-court cases from the 1880s, not PTAB proceedings, and they do not affect present-day enforceability.

Recommended next steps

1. If you are a defendant and have received a demand citing US 315,550: do not build an invalidity case and do not budget for IPR. The patent's own cover page and Google Patents record show Anticipated expiration 1902-04-14 and Status: Expired - Lifetime (https://patents.google.com/patent/US315550/en). Respond with a status-and-expiration letter. A pre-suit demand on an expired patent is a strong candidate for a Rule 11 / § 285 fee-shifting argument if litigation is actually filed.
2. Verify the patent number the sender meant. The most likely scenarios are (a) a typo or bad OCR of a modern patent number, or (b) deliberate citation of an expired patent to create an appearance of portfolio depth. Ask the sender to identify the asserted claim and the expiration date. If they cannot, that answer is your leverage.
3. Cross-check against modern numbers that collide on OCR. If the citation came from a scraped source, confirm it is not US 3,155,550 (a seven-digit 1960s-era number) or US 5,378,043-style formatting. I did not find a live US 3,155,550 in these searches, so I am flagging the possibility rather than asserting it.
4. Watch for related, unexpired family members. Nothing in this record suggests any, but if the demand letter references a continuation, reissue, or continuation-in-part claiming priority to the 1884-11-10 filing, that document needs its own expiration analysis — a pre-1995 term would still have run decades ago. Request the full priority chain in writing.

Bottom line: there is no PTAB story here, and the absence of one is not the interesting fact. The interesting fact is that US 315,550 has been expired for 124 years. Any assertion of it today is baseless on its face, and no IPR analysis is required to dispose of it.

I'll start by verifying the record for US 315550 across the assignment and legal-event sources.

Let me probe the assignment databases directly and check the inventor's business context.

Let me check the sibling Renchard patents and the Google Patents legal-event/assignee record.

Inventors

Francis J. Renchard — sole named inventor. Residence and citizenship: Detroit, Wayne County, Michigan (stated in the specification: "FRANCIS J. RENCHARD, of Detroit, in the county of Wayne and State of Michigan"). Application filed 1884-11-10; patent issued 1885-04-14; no model; no assignee named on the face of the patent.

Attorneys/agents of record at filing: none named. The only other individuals appearing in the document are the two subscribing witnesses, William May and John Marshall — these are witnesses to the inventor's signature, not attorneys of record, and not correspondents of record for any assignment.

Employer at time of filing: not determinable from the patent or from any source I could reach. Contextual (not dispositive) note: the surname Renchard recurs in the Detroit steam-engine lubricator trade in the immediately preceding decade. In Detroit Lubricator Manuf'g Co. v. Renchard, 9 F. 293 (C.C.E.D. Mich., opinion Aug. 15, 1881; bill filed May 4, 1881), the defendants J. Vincent Renchard and John J. Renchard were independent lubricator makers in Detroit who defended on their own patent No. 184,426 (granted 1876-11-14) and lost to the assignees of Charles H. Parshall (patent No. 191,171). That establishes a Renchard family lubricator business in Detroit but does not establish that Francis J. Renchard was employed by any particular entity. I have no evidence of an employer and will not guess at one.

Unusual-pattern check: the prompt's classic "all inventors depart within 12 months" tell is structurally inapplicable here — single inventor, no corporate assignee, and therefore no employer–employee assignment instrument to sign. There is no assignment document for the inventor to have departed from. Not present / not applicable.

Original assignee

None. US 315,550 issued to Francis J. Renchard as individual owner. The specification contains no "assignor to" recital, and the Google Patents bibliographic record for US315550A lists no original assignee and no current assignee. The live "family" on Google Patents is the single US application (family ID 2384699), country status: US only — no foreign counterparts, no continuation family.

Because there was never an assigning corporation, the standard questions in this section have no answer:

• Product shipping the claims: The patent is a steam-engine displacement lubricator (external water/steam condensing chamber A surrounding internal oil chamber B; oil displaced by condensed water and fed drop-by-drop through a water-filled sight glass J to the steam pipe via pipe N). The device as claimed was clearly a manufacturable article, and the surrounding 1870s–1880s Detroit lubricator litigation shows a real commercial market for exactly this class of apparatus — but I found no evidence that Renchard ever organized a company, branded the lubricator, or sold the embodiment. Treat "never commercialized" as unclear, not as a finding.
• Primary line of business: Individual inventor, occupation not of record.
• Current status: Individual inventor, deceased (19th-century filing). The patent itself expired 1902-04-14 per the anticipated-expiration legal event on Google Patents — a 17-year term from the 1885 grant, consistent with pre-1995 law.

Data-quality caveat for the cross-referencing step: the Google Patents "Cited By" entry for US315550 (EP0421229A1, General Electric, "Creep, stress rupture and hold-time fatigue crack resistant alloys," priority 1989-10-04) is facially impossible as a substantive citation to an 1885 steam lubricator. Treat it as a mis-tagged/erroneous citation record rather than evidence of a live assertion lineage. Note also that the "Prior art date 1885-04-14" field is simply the grant date, not a true prior-art date.

Assignment timeline

No recorded assignments exist for US 315,550 — none surfaced, on any source I could reach. Stating this plainly, as instructed:

• Google Patents legal events (the authoritative full text supplied for this analysis, fetched 2026-09-24) list exactly three events: 1885-04-14 Application granted, 1885-04-14 Publication of US315550A, and 1902-04-14 Anticipated expiration. There is no "Assignment" legal event of any kind, and the "Cited By / Similar Documents" machinery — which on Google Patents is driven by the same bibliographic spine — shows a family of one application, no assignee, no assignee-history widget populated.
• My open-web searches specifically targeting a reel/frame record for this patent number returned nothing. No reel/frame, no conveyance type, no assignor/assignee pair, and — critically for the correspondent-based tell you asked about — no correspondent attorney of record to capture.

Limits of this finding, stated candidly: my only live tool for this task was general web search. I could not execute a structured query against the USPTO Assignment Center API or the legacy Patent Assignment Search form, so I cannot represent this as a first-hand negative query of the assignment database — it is a "no records found" result across the authoritative patent text supplied plus open-web indexing. You should confirm directly at the Assignment Center ( https://assignmentcenter.uspto.gov/ , search by patent number 315550) before relying on the negative. Two further caveats: (a) the USPTO's searchable assignment database is periodically re-loaded and pre-20th-century records are indexed unevenly, with some 19th-century conveyances surviving only in paper assignment books or the annual Index of Patents; (b) a physically unrecorded but legally effective assignment could exist, since recordation has never been a condition of validity, only of priority against subsequent purchasers.

Per your instruction, I am stopping the reel/frame enumeration after this section — there are no entries to enumerate.

Timeline diagram

timeline
    title Ownership of US 315550
    1881 : Renchard kin lose Detroit lubricator suit
    1884 : Application filed by Francis J Renchard
    1885 : Patent issued to Renchard as sole owner
    1902 : Patent expires still in inventor hands

NPE / troll-pattern signals

Every signal below is evaluated against the record that exists: an 1885 individual-inventor grant with a family of one and no recorded conveyance.

1. Shell-entity transfer — not present. No transfer of any kind, so no movement from an operating assignee to a licensing LLC. No "IP / Holdings / Licensing / Ventures" party appears anywhere on the patent, in the Google Patents assignee field, or in any indexed record. No registered-agent address, no single-member Delaware or Texas LLC, no reel/frame to cite — because there is no assignment.

2. Known asserter in the chain — not present. No assignee has ever been recorded, so there is nothing to compare to Acacia, Marathon, IV, Wi-LAN/Conversant, Vringo, Pendrell, Round Rock, Spangenberg entities, or any Unified Patents / RPX high-frequency-plaintiff list. Independently, the patent expired 1902-04-14, so it cannot be asserted today by anyone and would never surface on a modern assertion directory. RPX and Unified track litigation activity; there is none for this patent.

3. Repeat correspondent across the chain — not present, and untestable. With zero assignment records there is no correspondent of record, no firm name, no address to test for recurrence. I have nothing to cite and will not name an attorney.

4. Cascading transfers — not present. No chained LLCs, no consecutive assignments, no shared correspondent address, no common principals. Nothing within 24 months of anything.

5. Pre-litigation transfer — not present. No assignment, and no infringement suit naming US 315,550. The only 19th-century litigation in the neighbourhood of this patent family is Detroit Lubricator Manuf'g Co. v. Renchard, 9 F. 293 (C.C.E.D. Mich. 1881), and that case is (a) about the Parshall patent No. 191,171, not this one, (b) about the Renchard brothers' own patent 184,426, and (c) dated 1881 — three years before the 1884-11-10 filing of US 315,550. It is therefore a market/prior-art context signal, not a chain-of-title signal.

6. Bankruptcy fire-sale — not present, and chronologically impossible. No corporate assignee ever existed to enter Chapter 7 or 11 — the Bankruptcy Act of 1898 was thirteen years after this patent issued, and the patent had expired six years before that Act passed.

7. Privateering — not present. No operating company ever held the patent, and no NPE was ever funded to assert it. There is no SEC filing to check for this patent; the assignee is a natural person from the 1880s.

8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN. It terminates with the inventor, by expiration of the 17-year term on 1902-04-14. Note the inverse of the usual finding: a patent reaching a defensive aggregator has been neutralized; this one was never weaponized in the first place.

Verdict

Insufficient data (no records beyond the original grant; and here, not even a recorded original assignment).

Justification: the only ownership events in the record are the intrinsic ones — filed 1884-11-10 by Francis J. Renchard, granted 1885-04-14 to Renchard individually, expired 1902-04-14 — with no recorded assignment, no reel/frame, no conveyance type, no assignee entity, and therefore no correspondent of record. There is no shell entity, no known asserter, no cascading transfer, and no pre-litigation transfer to evaluate, and the patent's 1902 term expiry makes every modern NPE pattern in your list chronologically unavailable. The absence of a post-issuance assignment record is itself the finding: the original individual owner, Francis J. Renchard, held the patent to expiration.

Verification link — USPTO Assignment Center, search property number 315550: https://assignmentcenter.uspto.gov/ . Google Patents copy of record (legal events panel confirms no assignment events): https://patents.google.com/patent/US315550/en .

I'll research this systematically. Let me start with searches on the patent itself and its citation records.

The patent's own citation record is minimal (one forward citation). Let me pull details on the "Similar Documents" list and the litigation-referenced prior patents to build the prior-art picture.

Bottom line up front

US 315,550 has no examiner-cited prior-art list — that practice didn't exist for an 1885 patent, and the Google Patents record for it shows only a single forward citation plus an algorithmic "Similar Documents" list. So the prior art below is reconstructed from (a) the one forward citation, (b) the Similar Documents list, and (c) the contemporaneous infringement litigation over the Renchard/Parshall lubricator family, which is where the real anticipation evidence for this art unit lives.

⚠️ Two caveats before the analysis:

1. The one "cited by" reference is not prior art. Google Patents lists EP0421229A1 (priority 1989-10-04; published 1991-04-10; General Electric; "Creep, stress rupture and hold-time fatigue crack resistant alloys"). That is a later document citing US315550, in an unrelated field (metallurgy). It cannot anticipate anything, and its presence here is almost certainly a classification/data artifact.
2. §102 is anachronistic for this patent. US315550 was filed November 10, 1884 and granted April 14, 1885. Novelty then ran under Rev. Stat. §§4886/4920, not 35 U.S.C. §102 (1952). I use the §102 framework below because you asked for it, but the operative test is "not known or used by others before his invention; not patented or described in any printed publication; not in public use or on sale for more than two years" — and the 1885 case law imported a strict "single reference must show all the elements" rule for anticipation, with combinations of old elements upheld as patentable.

1. The patent under analysis (for claim mapping)

US315550A — "Lubricator." Francis J. Renchard, Detroit, Wayne County, Michigan. Filed Nov. 10, 1884. Granted Apr. 14, 1885. No model. Retrieved from https://patents.google.com/patent/US315550/en

Claim set (paraphrased for mapping):

• C1 — Oil-chamber surrounded and inclosed by an exterior water/steam chamber, + transparent tube through which oil passes in visible quantities on its way to the part lubricated.
• C2 — Interior oil-chamber B + exterior water/steam chamber A + valve D admitting water in regulated quantities + tube discharging oil from the upper part of the oil-chamber as water enters at the bottom.
• C3 — Chambers A and B + tubular regulating-valve D + central valve E exhausting the interior chamber through the exterior chamber.
• C4 — External chamber A + internal chamber B + glass-holders I I + intermediate indicating-glass J + induction and discharge pipes (t, t′).
• C5 — Oil-chamber and steam/water chamber "arranged in the same plane and separated by a single partition," through which heat is transmitted, + valves/pipes feeding water to displace oil.

2. The single citation record entry (NOT prior art)

Source: Google Patents US315550A "Cited By (1)."

3. Prior art candidates, with §102 mapping

A. Same-family / same-inventor art (highest relevance)

1. US 184,426 — Renchard (John J. & J. Vincent Renchard), "Improvement in Lubricators"

• Date: granted Nov. 14, 1876 (pre-dates US315550's 1884 filing by ~8 years).
• Disclosure (as described in the litigation record): a displacement lubricator in which the condensing chamber and oil cup are not directly secured to each other; the apparatus mounts to the steam pipe by a horizontal trunk; the condenser sits on top and the oil cup hangs from the outer end. A siphon tube carries condensed water into the glass cylinder, and the water "drops from the siphon close to the wall of the cup, and each drop of water is clearly visible as it settles down in the oil."
• Potential §102 relevance: C1 (transparent visible-feed tube) and C4 (glass indicator with connections to the chambers) — but note the visible drops in US184426 are water drops descending, whereas C1 recites oil passing in visible quantities toward the part to be lubricated. Also relevant to C2 (water displacing oil).
• Source: Detroit Lubricator Manuf'g Co. v. Renchard, C.C. E.D. Mich., Aug. 15, 1881 — https://app.midpage.ai/document/detroit-lubricator-manufg-co-v-renchard-[8309429](/patent/8309429) ; Jenks v. Swift, 25 F. 722 (C.C.N.D.N.Y., Nov. 26, 1885) — https://law.resource.org/pub/us/case/reporter/F/0025/0025.f.0722.pdf

2. US 288,665 — listed in Similar Documents with inventor rendered "benchard"

• Date: Nov. 20, 1883 (pre-dates filing).
• Note: the inventor string "benchard" is an OCR corruption in the Google Patents similar-documents table, plausibly of "Renchard." ⚠️ I could not verify this record's contents (search budget exhausted). Treat as an unverified candidate, but if it is indeed an 1883 Renchard lubricator patent, it is a same-inventor, pre-filing reference that must be checked against C1–C5 before any validity opinion.

B. Key third-party anticipation art (pre-1884-11-10)

3. US 187,964 — William A. Clark, "Improvement in Lubricators"

• Date: filed Oct. 24, 1876; granted Mar. 6, 1877.
• Disclosure: metallic cylindrical cup Δ with a glass gage-tube G connected at top and bottom to the cup; a condenser chamber O on top of the cup, steam pipe B; tube V with stop-cock connecting condenser to the cup; a check-valve a in chamber r; and critically a drip-tube P whose end is cut slanting so condensed-water drops are delivered against the side of the glass so the operator can watch the feed.
• Litigation: Jenks v. Swift, 25 F. 722 (C.C.N.D.N.Y. 1885) — Clark's claim 2 (slant-ended drip-tube) was narrowly construed against the prior art and held not infringed.
• Potential §102 relevance: C4 (glass tube connected to both chambers + condenser + check valve) and, in combination with the Gates patents, C1.

4. US 107,478 — John Gates (granted Sept. 20, 1870) and the Gates patent granted Apr. 29, 1873

• Disclosure: displacement lubricator in which drops of water descend through oil in a glass cylinder to displace oil into the lubricated parts (1870 patent); the 1873 patent is for the inverse — drops of oil passing upward through a glass cylinder filled with water, "whereby the amount supplied to the engine can be observed by the engineer."
• Potential §102 relevance: the 1873 Gates patent is the closest art to C1, because C1's "transparent tube through which the oil passes in visible quantities" is exactly the 1873 Gates concept. The 1870 Gates patent is relevant to C2 (water displacing oil) and the visible-feed function.
• Source: Seibert Cylinder Oil-Cup Co. v. Newark Lubricator Manuf'g Co., 35 F. 509 (C.C.D.N.J.) — https://law.resource.org/pub/us/case/reporter/F/0035/0035.f.0509.pdf
• ⚠️ I was unable to verify the patent number of the 1873 Gates patent; the case names only the date. Do not assume it.

5. US 111,881 — Nicholas Seibert, "Improvement in Lubricators"

• Date: granted Feb. 14, 1871 (reissue line runs through USRE10153E, pub. 1882-07-11, "Lubricating device for steam-engines," which appears in US315550's Similar Documents list).
• Disclosure: water reservoir D filled by condensed steam; oil cup F; glass tube J with gage K showing oil quantity; check-valve H; oil pipe E to the steam pipe; and — importantly — concentric vertical tubes O and P with an annular space q kept hot by steam entering from the steam chest via passages S S′; a cock M admits steam directly into the oil cup F when tallow is used.
• Potential §102 relevance: this is the most probative reference for the heat-maintenance element of C5 (heat transmitted through a partition separating steam from oil) and for the oil travels through a glass indicator + check valve to the steam pipe architecture in C1/C4.
• ⚠️ USRE10153E's subject matter is ambiguous in my sources: the Google Patents similar-documents table lists it under US241936A (A. Craft, "Lubricating device for Steam Engines," May 24, 1881), while the Siebert reissue line is separately litigated in Garratt v. Siebert, 98 U.S. 75. Verify whether RE10153E reissues the Craft patent or a Siebert patent before relying on it.

6. US 191,171 — Charles H. Parshall, "Improvement in Lubricators"

• Date: granted May 22, 1877 (application filed earlier). Litigated in Detroit Lubricator Manuf'g Co. v. Renchard and Tucker v. Sargent (9 F.).
• Disclosure: supporting stem with independent steam and oil ducts connecting the main steam pipe to the condensing and oil-feeding chambers; a water-pipe connecting the condenser with a glass indicating tube; a water-seal tube acting as a siphon so oil cannot back into the condenser; a metal oil cup with a check valve through which oil is forced drop by drop to the steam pipe. Claim 6 was: "The combination with the oil chamber and condensing chambers, directly secured to each other, of a water seal pipe … and a glass indicator, the ends of which have free communication with the oil chamber."
• Potential §102 relevance: this is the closest functional prior art to C2 and C4 (condenser + oil chamber directly joined; glass indicator open at both ends to the oil chamber; regulated water feed; check-valve discharge). It is not a clean anticipation of C1 or C5 because Parshall's chambers are stacked vertically with the condenser above the oil cup (a diaphragm between them), not concentric / "in the same plane … separated by a single partition." That geometric distinction is precisely what US315550's C5 recites, and appears to be the point of novelty over Parshall.
• Source: https://app.midpage.ai/document/detroit-lubricator-manufg-co-v-renchard-8309429

7. US 191,425 — James Harper, "Improvement in Lubricators for Steam-Engines"

• Date: filed Mar. 17, 1877; granted May 29, 1877.
• Disclosure: oil reservoir A; condenser O arranged above the reservoir; condensate drains down tube D into the reservoir A through a valve i that is continuously adjustable; a return passage (F, chamber l, valve n, tube H, passage m) back to the steam pipe, producing equilibrium so the oil is floated out without pressure; valves g and g′ regulate the steam/condensate circuit.
• Potential §102 relevance: C2 — "a valve for admitting water … in regulated quantities, and a tube for discharging the oil from the upper part of the oil-chamber as water is introduced at the bottom" is closely read on Harper's adjustable valve i + return/flotation to the steam pipe. Harper does not disclose an oil chamber enclosed by a water/steam chamber (C1/C5).
• Source: https://patentimages.storage.googleapis.com/1e/7a/d4/41823d70843c1c/[US191425](/patent/US191425).pdf

8. US 169,124 — W. P. Stevenson

• Date: granted Oct. 26, 1875.
• Relevance: expressly pleaded as anticipation of the Parshall patent in Detroit Lubricator Manuf'g Co. v. Renchard (as reported at 9 F.). It is therefore part of the adjudicated prior art of this exact art unit, and any validity analysis of C1–C5 should start here. ⚠️ I did not retrieve its disclosure text — treat the specific claim mapping as unverified.

C. Similar-Documents entries that are not prior art (post-filing)

These appear in Google Patents' "Similar Documents" table but have publication dates after the Nov. 10, 1884 filing date, so they cannot be §102 art unless their own filing/priority dates precede it (unverified):

D. Similar-Documents entries with pre-filing dates that I could not verify (unverified candidates)

US201402 (1878-03-19, "Improvement in steam-engine lubricators"), US228216 (1880-06-01, "Lubricator"), US250944 (1881-12-13, "Lubricator"), US273312 (1883-03-06, "Lubricator"), US293590 (1884-02-12, "Lubricator"), USRE10153E (1882-07-11, "Lubricating device for steam-engines"). Each is date-qualified as possible §102 art; contents unverified.

4. Claim-by-claim anticipation summary

Overall: none of the located references appears to be a complete, single-reference §102 anticipation of independent claim 1 or claim 5. The prior art presses hardest on claims 2 and 4, which are the pure combinations of old elements (condenser + regulating valve + glass indicator + discharge piping). That is consistent with how the 1885-era bar treated this art: in Jenks v. Swift the court narrowed the Clark drip-tube claim to its precise geometry and found no infringement; in Tucker v. Sargent and Detroit Lubricator v. Renchard the courts cabined the Parshall combination to "the oil and condensing chambers directly secured to each other," expressly because of "the state of the art at the date of the patent."

5. What I could not confirm (stated explicitly rather than fabricated)

• The cover/face citation list of US315550 itself — 1885 patents have none; no examiner-cited art exists in the record.
• The patent number of the Gates 1873 patent (the case names only the April 29, 1873 grant date).
• Whether USRE10153E reissues the Craft patent (US241936) or a Siebert patent.
• The disclosures of US288665, US201402, US228216, US250944, US273312, US293590, US169124 — I have their dates/titles only.
• The Federal Reporter volume/page for Detroit Lubricator Manuf'g Co. v. Renchard — sources point to the 9 F. reporter series and the Aug. 15, 1881 C.C. E.D. Mich. sitting, but I did not verify the exact page.

Primary sources used: https://patents.google.com/patent/US315550/en (authoritative full text supplied) · https://patentimages.storage.googleapis.com/1e/7a/d4/41823d70843c1c/US191425.pdf · https://patentimages.storage.googleapis.com/7f/da/22/1c5b7afd1946de/US187964.pdf · https://patentimages.storage.googleapis.com/0d/1d/d0/7840a197c79529/US111881.pdf · https://law.resource.org/pub/us/case/reporter/F/0025/0025.f.0722.pdf · https://law.resource.org/pub/us/case/reporter/F/0035/0035.f.0509.pdf · https://app.midpage.ai/document/detroit-lubricator-manufg-co-v-renchard-8309429

I'll ground this analysis in the actual prior-art references surfaced on the patent page, rather than working from memory. Let me pull details on the closest "Similar Documents" and the citation.

Obviousness Analysis — US 315,550 (Renchard, "Lubricator," Apr. 14, 1885)

0. Threshold caveats (read first)

1. § 103 did not exist when this patent issued. 35 U.S.C. § 103 was created by the Patent Act of 1952. US 315,550 was granted in 1885, filed November 10, 1884, and expired April 14, 1902. The governing test at the time was the "invention" requirement of Hotchkiss v. Greenwood, 52 U.S. 248 (1851) — whether the improvement rose above the mere skill of the mechanic. Everything below is therefore a retrospective/hypothetical § 103 exercise applying Graham v. John Deere, 383 U.S. 1 (1966), and KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007). Ancient-court outcomes on lubricator combinations were decided on "invention," not "obviousness," and are not interchangeable.

2. Prior-art window. Filing date Nov. 10, 1884; invention date presumptively on or just before that. Pre-AIA § 102(a)/(e) art must predate the invention.

3. Retrieval failures I will not paper over. The Similar Documents list on the patent page includes US 273,312, 250,944, 293,590, 228,216, 201,402, 191,171, 288,665, 456,422, 802,581, and RE10,153. My searches for four of these returned different patents (e.g., querying 293,590 returned Bailey US 298,813 and Gates US 238,674; querying 250,944 returned Gates 238,674 and Harrub US 253,282). I could not verify their content and do not rely on them. The analysis rests only on references I actually retrieved.

4. EP0421229A1 (GE, 1991, creep/crack-resistant alloys) is not prior art to anything here — citation noise, as the prior summary already noted.

1. Person having ordinary skill in the art (PHOSITA)

A machinist/mechanical engineer of c. 1884–85 working in steam-engine lubrication: familiar with (a) displacement ("hydrostatic") lubricators, (b) sight-feed glass indicators and their breakage problem on locomotives, (c) needle/drip and compound gauge-cock valve construction, (d) stuffing boxes and foundry practice for cast concentric cylinders. This is a crowded, incremental art — the record shows dozens of lubricator patents in the 1870s–80s.

2. Prior art actually retrieved and verified

Not prior art: US 773,545 (1904) postdates 315,550 by 19 years. I cite its statement that condensate "serves to keep the oil in a workable or liquid state" only as corroboration of what a PHOSITA understood, not as § 102 art.

3. Claim-by-claim

Claim 1 — jacketed oil chamber + visible-feed transparent tube

Combination: Clark 187,964 (or Parshall or Renchard 184,426) + the unidentified "condenser-within-reservoir" reference.

• Clark 187,964/Parshall supply every element except the enclosure: metal lubricant reservoir, external glass indicator, visible drop feed, check valve.
• The unidentified reference supplies the enclosure and, critically, an express motivation: moving the condenser inside the reservoir makes condensation "more rapid and certain at the start, when most needed" and renders the device "less clumsy and less liable to damage." Compactness, thermal coupling, and protection were the stated reasons.
• Independent motivations in the art: (i) glass oil cups break under locomotive vibration — the Detroit Lubricator opinion records this as the very reason metal cups plus external indicators were adopted; (ii) heavy oils and greases thicken in cold weather, which is why later references steam-jacket the reservoir. Heating the oil by nesting it in the hot condensate chamber is an inevitable, inherent consequence of the arrangement, not a new mechanism.
• Assessment: obvious. Under KSR, substituting a known thermal-coupling arrangement for a known separate condenser is the predictable use of a prior-art element. The only non-cumulative feature — why one would enclose the oil rather than the condenser — is answered by the reference's own "less clumsy, less liable to damage" rationale.

Claim 2 — chambers A/B + regulating water valve D + oil drawn off the top as water enters the bottom

Combination: Gates US 107,478 + Gates US 238,674 + Clark US 122,861 + the unidentified reference.

• Gates 107,478 explicitly describes "injecting jets of water into the bottom of the lubricator, and causing the oil above to rise in proportion to the amount of water thus injected."
• Gates 238,674 claims "a water-pipe extending downward into the oil-tank to a point near the bottom," with an intermediate cock regulating flow — i.e., the regulated water valve D.
• Clark 122,861 teaches the same tube-to-near-the-bottom geometry with oil forced upward into the steam pipe.
• Only the exterior water/steam chamber A remains, and the unidentified reference supplies it.
• Assessment: obvious — arguably anticipated in substance. This claim is the displacement lubricator, which was thoroughly old art by 1884.

Claim 3 — tubular regulating valve D with central drip valve E exhausting B through A

This is the strongest claim on the record, and it is still vulnerable.

The specific structure — a hollow valve stem with an internal valve seat and a finer-pitch valve screwed into its center so the drip can be opened "without disturbing valve D" — was not found in any reference I retrieved. Gates 238,674's intermediate cock and waste cock, Harrub's pet-cocks, and Bailey's dual-purpose spindle are separate valves, not concentrically nested ones.

However: compound cocks with a coarse outer needle and a fine inner needle (gauge cocks, steam cocks) were standard mechanical vocabulary, and the claimed advantage (independent adjustment of two coaxial valves) is what such construction is for. Under KSR's "predictable variation of known techniques," a PHOSITA seeking a drain that would not disturb the feed setting would hollow the stem. Assessment: likely obvious, but this is the claim where a nonobviousness argument has the most purchase. Note the specification concedes the point: "it is not essential that the regulating and drip valves should be united… as the same end can be accomplished by independent and distinct valves."

Claim 4 — chambers A/B + glass holders I, I′ + indicating glass J + induction/discharge pipes

Combination: Clark 187,964 + Gates 238,674 + Harrub 253,282 + the unidentified reference (guard F, gauge-tube I, packing-rings e within reservoir B).

Glass sight tubes held between upper and lower holders and sealed by packing rings/washers, with inlet and outlet pipes, are disclosed in Harrub (stuffing boxes), Clark 187,964 (indicator communicating at both extremities, check valve), and the unidentified reference (gauge-tube and packing rings inside the reservoir). The claim is a sub-assembly of well-known parts. Assessment: obvious.

Claim 5 — broad functional claim: oil chamber and steam/water chamber "in the same plane," separated by a single partition, heat transmitted through the partition

This is the deliberately broadest claim and the most exposed.

• The unidentified reference's condenser-within-reservoir is separated from the oil by exactly one cylindrical partition, with heat transmitted through it.
• US 315,551 — same inventor, filed the same day — claims the mirror-image structure: an oil chamber surrounding and enclosing an interior steam and water chamber, separated by one partition.
• The specification itself concedes breadth: "it is not essential that the oil-chamber should be entirely inclosed in the steam and water chamber," and the "same plane / single partition" language is a deliberate attempt to capture any side-by-side or concentric heat-transfer relationship, not just the cast concentric cylinders of Fig. 2.
• Assessment: obvious. A genus this broad, covering both the disclosed embodiment and its mirror image, is the classic case of a claim that adds only an obvious design alternative to the prior art.

4. Motivation-to-combine summary

1. Anti-breakage (documented in Detroit Lubricator Mfg. Co. v. Renchard): locomotive vibration shatters glass oil cups → metal reservoir + separate glass indicator. Both elements were old.
2. Anti-thickening / cold weather: heavy lubricants must be kept fluid; the art already knew condensate was hot. US 773,545 states the result later, but the physical fact was inherent.
3. Condensation efficiency + compactness, stated in terms in the unidentified reference: condenser inside reservoir = "more rapid and certain at the start," "less clumsy," "less liable to damage."
4. Fewer joints / simpler casting: the 315,550 specification itself says the "special arrangements of the integral parts… facilitate… construction," confirming that the arrangement was a manufacturing convenience rather than a new principle.
5. Displacement is a settled principle: Gates 107,478, Gates 238,674, Clark 122,861, and the Siebert ("hydrostatic pressure") line of cases all teach water-in-at-bottom / oil-out-at-top.

5. The most concrete obviousness finding on this record

US 315,551 is the best evidence against 315,550. It is by the same inventor, filed the same day (Nov. 10, 1884), issued the same day, and claims the inverted arrangement — oil chamber surrounding an interior water/steam chamber, single cylindrical partition, transparent tube with visible feed. Under pre-AIA § 102, 315,551 is not prior art to 315,550 (it is not "by another," and it was not filed before the invention). But:

• It is powerful evidence that the choice between "oil inside water" and "water inside oil" was, to this inventor, an obvious design alternative captured in a single day's drafting — the essence of a § 103 (and obviousness-type double patenting) problem.
• Both patents claimed the same general concept (nested chambers, single partition, heat transfer, visible feed) with the recited nesting reversed. Neither claim recites a result that depends on which chamber is inside.
• This is precisely the situation in which the 1885-era objection would have been "no invention," and in which a modern § 103 analysis would find the two claims not patentably distinct.

6. Honest counterweight (why a court could still uphold it)

• No retrieved reference explicitly states the heating purpose. The unidentified reference's rationale for nesting is condensation speed and robustness, not keeping oil fluid. If a tribunal insists on an express teaching, motivation becomes an inference from inherent results — strong under KSR/In re Kerkhoven, but an inference nonetheless.
• The examiner allowed it in 1885 over Gates, Clark, Parshall, and Renchard 184,426, all of which were in the Office. Office allowance carries evidentiary weight (see Tucker v. Sargent, where the court deferred to the patent examiners' determination on the Parshall combination).
• Contemporaneous courts upheld analogous lubricator combinations — Tucker v. Sargent (Parshall) and Detroit Lubricator treated old-parts/new-combination lubricators as patentable under the 1885 "invention" standard.
• Claim 3 has no closely matching reference in my retrieval; the concentric drip-within-regulating-valve structure is the claim most likely to survive.
• Objective indicia: a real commercial need existed (freezing oil, broken sight glasses), and the art was crowded — crowdedness cuts both ways, but it supports nonobviousness of the combination if the need was long-felt and unmet.

7. Bottom line

On the retrieved record, claims 1, 2, 4, and 5 are obvious under KSR — principally over the unidentified "condenser within the reservoir" reference in view of Clark 187,964, Clark 122,861, Gates 107,478 and Gates 238,674 — and claim 5 is the most vulnerable because it was deliberately drafted to cover both nesting orientations and is contradicted by the inventor's own same-day US 315,551. Claim 3 is the only claim with a credible nonobviousness position, resting on the absence of any retrieved reference to a drip valve coaxially nested in a hollow regulating-valve stem.

Two verification gaps remain that I could not close within this session and that I will not guess around: (a) the number, date, and inventor of the unidentified "condenser within the reservoir" reference, which is my single most important citation; and (b) the content of Similar-Document IDs 273,312, 250,944, 293,590, 228,216, 201,402, 191,171, 288,665 and RE10,153 — several of which, by their 1877–1884 dates, may be closer art than anything I did retrieve.