US 3422831

I'll check the litigation/status angle first, then summarize from the authoritative patent text.

Let me verify status and check for any litigation records under the exact number.

US 3,422,831 — Summary

Sourcing note: I found no CAFC 2026 docket entry and no litigation record for this patent; the litigation searches returned nothing relevant (only an unrelated EP 3422831 thermally conductive sheet, which is not this patent). The USPTO record surfaces only through the Google Patents/PatentCenter listing, which is the authoritative text I rely on below. Treat the "no litigation" finding as a null search result, not as affirmative proof no case exists.

Bibliographic data (from the patent's own front matter)

Minor discrepancy to flag: the patent's own front matter (reproduced by Google Patents) states filed Feb. 20, 1967 and issued Jan. 21, 1969. A third-party aggregator (Unified Patents) lists priority 1967‑02‑19 and grant 1969‑01‑20. I give the self-reported patent dates above; the aggregator dates differ by one day and should be verified against USPTO PatentCenter if exact dates matter.

Abstract (as printed)

"Steam turbine has forward and reversing valves actuatable together in opposite directions by racks and pinions which can be selectively clutched or declutched to a common electrohydraulic power amplifier to enable independent or simultaneous movement of the valves. The power amplifier includes a combined AC synchro and hydraulic servo control responsive to AC valve positioning signals which are modified in the event of turbine overspeed."

Background the patent positions itself against

The stated problem: prior marine turbine throttle systems achieved independent/simultaneous ahead-and-astern valve control by using two complete electrohydraulic control units, each with its own reversible variable-delivery pump and constant-displacement motor — "adds greatly to the cost." DC operational-amplifier systems are also criticized as expensive and more accurate than necessary. The invention's answer is a single common power amplifier shared by two control loops.

Plain-language overview of the independent claims

Claim 1 — the system claim (a control architecture for a reversing turbine)
A control system for a reversing turbine having a first valve (forward steam admission) and a second valve (reverse steam admission). It requires:

1. first control means responding to a first valve-positioning signal to position the forward valve;
2. second control means responding to a second valve-positioning signal to position the reverse valve;
3. power amplifier means common to portions of both control means (the core cost-saving point);
4. the two control means arranged to move the two valves in opposite senses with respect to steam-flow control when driven by that common amplifier output (e.g., via the rack-and-pinion/gear arrangement of Fig. 1); and
5. logic means for selectively running the two control means either independently or simultaneously.

Claim 6 — the valve-positioning control system claim (AC synchro channel)
A valve-positioning control system for a turbine comprising:

• a power amplifier connected to move the valve in response to an AC signal;
• an AC synchro control input channel coupled to that amplifier, containing three synchro elements in series:
  • a synchro control transmitter (CX) producing an AC reference signal corresponding to desired valve position;
  • a synchro control differential transmitter (CDX) that modifies the positioning signal by changing the relative orientation of its rotor and stator windings in response to turbine overspeed (thereby calling for a lower valve opening); and
  • a synchro control transformer (CT) whose rotor is connected to actual valve position and which transmits an AC valve-position error signal back to the amplifier.

Dependent-claim highlights (context for the independent claims):

• Claim 2: the first/second control means include disengageable clutches; the logic means is valve-position-responsive and actuates the clutches at selected valve positions.
• Claim 3: an AC synchro mechanism derives both positioning signals from a common AC input, plus rate-of-change limiting on the amplifier output.
• Claim 4: gating means (the diode switch 15) admitting only one positioning signal at a time to the common amplifier. (The printed text reads "gating n cans," evidently a scanning artifact for "gating means.")
• Claim 5: recites the overspeed-responsive CDX limitation in the claim-1 context.
• Claim 7: rate limiting with means to defeat the limit for fast/emergency valve movement (pushbuttons 87/88).
• Claim 8: power amplifier output clutched to a spring-biased valve-moving mechanism, with speed-responsive means to disengage the clutch at a preselected overspeed.

Key operational concept described in the specification

On a full-ahead-to-full-astern command, both CT devices produce large error signals at the diode switch; only the closing-valve error signal is gated through. The closing valve (ahead) moves under closed-loop control; at about 50% flow the logic engages the astern clutch so the astern valve begins opening open-loop at the same rate. When the ahead valve fully closes, the logic disengages the ahead clutch and transfers to the astern feedback signal, putting the astern valve under closed-loop control for the remainder of its travel. Overspeed above a first threshold proportionally lowers the called-for valve position via the CDX rotor; beyond a maximum threshold, limit switches drop the clutches so valve springs close the valves. Figure 7 describes an analogous variable-speed mechanical-drive turbine variant using an AC tachometer-generator rate feedback, threshold circuit, diode switch, and clutch.

Confidence / uncertainty

• High confidence on title, inventors, assignee, application number, issue date, abstract, claim set, and cited art — all taken verbatim from the patent text.
• Medium confidence on exact filing date (Feb. 20, 1967 per the patent itself vs. Feb. 19, 1967 per an aggregator) and on the 1986 expiration date, which is an administrative/statutory projection.
• I did not find any CAFC 2026 docket activity or infringement litigation for US 3,422,831; absence in my search is not conclusive.

I'll search for litigation involving US patent 3422831.

Let me search more specifically for litigation records.

Let me check the Unified Patents litigation portal and other sources more specifically.

Litigation Search Results — U.S. Patent No. 3,422,831

Bottom line: I found no litigation involving U.S. Patent No. 3,422,831. No district court complaints, no CAFC appeals, no ITC Section 337 investigations, and no PTAB proceedings referencing this specific patent were located.

What I searched and what I found

Note on the USPTO reexamination "Litigation Search Report" that surfaced in results (Reexam Control No. 90/011,569) — that report concerned U.S. Patent 7,149,511, not 3,422,831, and is not relevant here.

Why no litigation is plausible

• Age/expiry: The patent was filed 1967-02-20, granted 1969-01-21, and its term expired around January 1986. Any infringement suit would necessarily have been brought before that date.
• Subject matter/owner: It is a 1960s-era General Electric marine steam-turbine throttle control patent (mechanical/hydraulic/synchro valve positioning). Such utility patents were litigated rarely, and I found no historical docket or reported decision tied to it.

Required per-case fields

Because no case was identified, I cannot supply plaintiff, defendant, jurisdiction, case number, filing date, or outcome/status for any matter. No known litigation exists for US 3,422,831 based on the sources searched.

Caveats (stated explicitly rather than guessed)

• I could not directly load the Unified Patents litigation caselist page for this patent beyond the snippet returned; the snippet showed empty "Related Cases"/"Opposition Documents" sections, which is consistent with zero recorded assertions, but I cannot rule out that a pre-1986 action exists only in paper/archival docket form not indexed online.
• PACER coverage for cases from the 1970s–1980s is incomplete, and pre-1980s district court filings are often not in electronic databases at all. Therefore "no litigation found" should be read as "none located in the searchable sources," not as a certified negative across all historical court records.
• I did not auto-correct any identifier: EP 3422831 A1 and the reexam report concerning 7,149,511 are distinct documents and were excluded.

If you want a higher-confidence negative, the next step would be a manual Westlaw KeyCite and Lexis CourtLink patent-history search (the same methodology USPTO uses in its Litigation Search Reports), plus a check of GE's historical litigation files — tools I do not have access to here.

I'll verify the structured data (no AIA trials indexed) against public sources before answering.

Proceedings overview

Zero AIA trial proceedings on file. The structured USPTO Open Data Portal block accompanying this task states that ODP returns no AIA trial proceedings for US 3,422,831, and my independent web searches surfaced none — no IPR, PGR, or CBM numbers, no institution decisions, no Final Written Decisions, no Federal Circuit appeals, and no defensive-aggregator filings. Bottom line for a defendant: there is no PTAB activity to work with, because there is no live patent to attack — US 3,422,831 issued 1969-01-21 on a 1967-02-20 application and reached its anticipated expiration on 1986-01-21 (Unified Patents' portal entry lists expiration 1986-01-20, a ±1-day database artifact). A pre-AIA patent that expired roughly four decades before the AIA trial regime existed cannot generate PTAB proceedings, and it cannot be asserted today either.

No proceedings to report

There is no {PROCEEDING_NUMBER} — {Petitioner} v. {Patent Owner} entry to render. Rather than fabricate one, here is what was actually verified:

Why the absence is structural, not accidental (this matters more than the count):

1. Expiration. The patent's 17-year term from the 1969-01-21 grant ran out 1986-01-21. Section 315(b)'s one-year clock is triggered by service of a complaint alleging infringement; a complaint alleging infringement of this patent served today would be legally baseless (any pre-1986 damages claim is time-barred as well as barred by the patent's own term). No petitioner can satisfy the time bar, so no IPR is even procedurally available in a real dispute.
2. Pre-AIA statutory gate. PGR under § 321 applies only to patents with an effective filing date on or after 2013-03-16 — categorically unavailable here. CBM under AIA § 18 reached only "financial product or service" patents, which this electrohydraulic marine turbine throttle control is not; the CBM program also sunset on 2020-09-16.
3. No commercial assertion pressure. Well-asserted patents attract IPRs; this one expired before most practitioners in the field were admitted. Its "cited by" record shows only two later GE family-style patents — US 3,986,364 ("Marine turbine control," 1976-10-19) and US 4,082,115 ("Valve operator," 1978-04-04) — i.e., GE's own follow-on filings, not third-party litigation pressure.
4. Prosecution-era validity challenge. The only cited prior-art reference of record is US 3,348,559 (Brothman et al., "Electronic governor," Baldwin-Lima-Hamilton Corp., issued 1967-10-24), plus a non-patent publication, Fluid Power News 25, The Oilgear Co. (1964), cited at class 137-22. Those were the examiner's § 102/§ 103 citations during prosecution; no post-issuance proceeding ever revisited them.

Strategic summary

Claim status: all eight claims are UNTESTED — and untestable. Claims 1–8 of US 3,422,831 (independent claims 1 and 6, with dependent claims 2–5 and 7–8) have never been subject to any AIA trial; no claim has been canceled, and none has been confirmed by the PTAB. The distinction is critical: the claims are not "sustained" in the sense of surviving an IPR — they simply were never challenged, because the patent died of old age in 1986. Claim 1 (a reversing-turbine control system with first/second control means, a common power amplifier, opposite-sense valve motion, and logic means for independent-or-simultaneous operation), claim 2 (disengageable clutches and position-responsive logic), claim 5 (the synchro control differential transmitter responding to turbine overspeed), and claims 6–8 (the AC synchro control input channel with CX/CDX/CT, rate limiting, and overspeed-responsive clutch disengagement) all remain in their as-issued form in the public record — but as an expired patent, not an enforceable one.

Estoppel landscape: § 315(e)(2) is irrelevant, and so is everything downstream of it. Because no IPR or PGR was ever instituted against this patent, no petitioner, real party in interest, or privy is subject to estoppel, and there are no IPR-canceled claims creating a carve-out. Correspondingly, there are also no "still-available" grounds for a defendant to preserve: the entire prior-art universe — including US 3,348,559, the Fluid Power News Oilgear publication, and any art a modern searcher would find — remains unpressed but also unneeded. An invalidity defense is the wrong tool here; the correct defense is the patent's own expiration date.

Pattern signals: none. No petitioner filed one IPR, let alone multiple; no patent owner appeal activity exists (no FWD to appeal); no Unified Patents, RPX, or other aggregator appears in the chain — the Unified Patents portal page for US-3422831-A appears only as a patent-data record, not as a petitioner. The patent's prosecution-era assignee was General Electric Company (the "Current Assignee" field still lists GE; the Unified portal's "parent company" field shows GE Video Compression, an artifact of GE's later corporate restructuring, not an ownership transfer relevant to 1960s marine turbine controls).

Recommended next steps

• If you have received a demand letter citing "US 3,422,831": confirm the number before doing anything else. The patent expired 1986-01-21 (Google Patents: "Anticipated expiration 1986-01-21"; Unified Patents: 1986-01-20) and has been unenforceable for roughly forty years — a demand premised on it is baseless, and a suit asserting it would be sanction-exposed. See https://patents.google.com/patent/US3422831/en and https://portal.unifiedpatents.com/patents/patent/US-[3422831](/patent/3422831)-A.
• Check for number-confusion. My searches repeatedly returned other "3422831" hits that have nothing to do with this patent: EP 3422831 A1 (Zeon Corporation, "Thermally conductive sheet," filed 2017-02-17, granted 2021-12-01) and unrelated US patents whose specifications happen to reference an "'831 patent." A demand letter that is actually targeting a live patent in that group would be a very different analysis. Get the issuing office and the specification title in writing.
• No PTAB milestones to diarize. There is no institution decision deadline, no oral hearing date, and no statutory FWD due date — because there is no trial. Any communication from opposing counsel describing a "pending IPR" on this patent is false on the record.
• Preserve the record now. Pull and retain the ODP proceeding search result (null) and the Google Patents / PatentCenter status page showing "Expired – Lifetime" with the 1986-01-21 anticipated expiration. That screenshot pair is the entire defensive file: no PTAB proceedings exist, and the patent's term ended before any could have.

Caveat on sourcing: the only "prior art"/citation data above comes from the authoritative full-text block provided in this task (Google Patents, fetched 2026-09-29). Because no PTAB proceeding exists for this patent, there is no Final Written Decision to quote, no judge panel to name, and no claim-by-claim disposition to report — I have not invented any of those.

I'll research the assignment record for US 3,422,831 before producing the analysis.

Let me probe the assignment database and ownership-status sources directly.

Assignment & Ownership Analysis — U.S. Patent No. 3,422,831 ("Turbine Control System")

Scope note / cross-reference: This section builds on the earlier litigation summary. That summary concluded (correctly, on the same record) that no litigation exists. One contradiction to flag between my sources and the prior section, and between sources generally:

These are ±1-day artifacts of date conventions, not conflicting ownership facts. Per the operating rules I do not auto-correct either; I simply note that the 1967 filing and ~1986 expiry are consistent across both.

Inventors

Evidence for the employer call: the patent's front page reads "Kenneth Orral Straney, Danvers, and Ove Mareno Sivertsen, Peabody, Mass., assignors to General Electric Company, a corporation of New York" — i.e., the inventors assigned to GE at filing (Ser. No. 617,320), which is the standard signature of employee-inventor work. This is corroborated by Straney's repeat appearances as a GE-assigned inventor in the same technical area, e.g.:

• US 3,233,413 — "James B. Wagner, Lynnfield, and Kenneth O. Straney, Danvers, Mass., assignors to General Electric Company" (filed 1963-06-21; electric control systems for elastic-fluid turbines).
• US 3,064,435 — "Control System," Wagner and Straney, assigned to General Electric (filed 1961-08-14; issued 1962-11-20) — cited on the face of US 3,233,413.

Unusual patterns: none of the red flags in the task template. Specifically:

• There is no evidence of inventors departing GE within 12 months of filing, and the opposite is suggested — Straney was a GE employee for at least ~6 years spanning the pre-filing (1961, 1963) and post-filing (1969 issuance) period, in the same GE turbine-control group.
• There is no pre-issuance personnel churn visible, and no evidence of a portfolio fire-sale.
• Caveat: I found no biographical or assignment-of-rights documentation for Sivertsen beyond this patent; I cannot state his tenure at GE with the same confidence as Straney's. State this as a gap, not a finding.

Original assignee

General Electric Company, a New York corporation (Schenectady, NY).

• Product embodying the claims? Yes — this is a shipboard marine steam-turbine throttle control (ahead/astern valve electrohydraulic servomechanism). GE's marine steam turbine and control business (Lynn, MA "River Works" and the former GE turbine-control product lines) commercialized exactly this class of equipment. The patent describes a production-oriented architecture (bridge/engine-room consoles, transfer switch, dual synchro channels, common hydraulic power amplifier), not a laboratory curiosity. The disclosure also states the FIG. 7 variable-speed turbine control is a "modification" applicable to other prime movers — i.e., a product-line family, not a one-off.
• Primary line of business: diversified industrial/electrical manufacturing; the relevant unit was GE's steam turbine & turbine-control business.
• Current status of the inventor organization: GE is an operating company, not a dissolved shell. It has not been acquired or liquidated, but it has undergone major structural separations since this patent expired:
  • GE's steam power / turbine business now sits in GE Vernova (spun off April 2024), which holds the legacy steam-turbine and turbine-controls lines.
  • GE's other successors (GE Aerospace; GE HealthCare, spun off 2023) are unrelated to this patent's subject matter.
• Current status of the patent itself: Expired — term ended ~January 1986 (anticipated expiration; 1967 filing, pre-URAA 17-year term). No maintenance fees were payable post-expiry. Unified Patents records "$0 lifetime renewal fees."

Assignment timeline

Finding: the USPTO Assignment Center produced no retrievable post-issuance assignment records for US 3,422,831 in the searches I was able to run. I queried the Assignment Center entry point (https://assignmentcenter.uspto.gov/) and the legacy index (https://assignment.uspto.gov/patent/index.html) by patent number, plus keyword probes for the inventors' names paired with "assignment" and "reel/frame." The searches returned:

• the patent's bibliographic record and the Unified Patents patent page (which shows Original Assignee: General Electric Co and no downstream assignee entries), and
• no reel/frame hits tying this patent number to any recorded conveyance.

I am therefore declining to list assignment links, because I have no reel/frame numbers and will not fabricate them. The only ownership transaction that demonstrably exists is the inventor→GE assignment recited on the face of the patent at filing (Ser. No. 617,320, filed 1967-02-20), which under 1960s practice was normally recorded shortly after execution/OTO filing. I could not retrieve that record's reel/frame from the sources reachable here, and I am not going to guess it.

Cross-checked sources and what each showed:

Caveat on the "GE Video Compression" parent-company field: the Unified Patents page renders a "Parent Company" value of Ge Video Compression. That appears to be a database attribution artifact (likely a PVIX/CITX field keyed to a modern GE affiliate), not evidence of any transfer of US 3,422,831. This patent does not concern video compression, and a GE video-compression affiliate did not exist in any form relevant to a 1967 turbine-control patent. I explicitly decline to treat it as an assignment record.

Bottom line for this section: the record is consistent with the original assignee, General Electric Company, having retained ownership through expiry in 1986 — the ordinary outcome for a 1960s captive-employee patent in a mainstream operating company's core product line. But because the Assignment Center rows were not retrievable in my searches, I flag the chain as "no post-issuance assignments located," not as a certified negative.

Timeline diagram

timeline
    title Ownership of US 3422831
    1967 : Filed by Straney and Sivertsen
         : Assigned to General Electric at filing
    1969 : Patent issued to General Electric
    1986 : Patent term expires
         : No post-issuance assignments located

Only events supported by the record above are plotted. No assignment reel/frame links are shown because none were retrieved.

NPE / troll-pattern signals

Verdict

Insufficient data — effectively operating-company-owned and non-asserting.

The chain consists of only the original, on-face assignment of the inventors' rights to General Electric Company at filing (Ser. No. 617,320, 1967-02-20), after which no post-issuance assignment records for US 3,422,831 were located in the USPTO Assignment Center / legacy Assignment Search, Unified Patents, or Google Patents legal events; the patent expired in January 1986 with GE as the apparent owner of record throughout. Zero of the eight NPE signals are present (one is a pure data gap because no conveyance rows — and therefore no correspondent — could be retrieved), so "NPE — high/moderate confidence" is unsupportable and "Operating-company assertion" is inapplicable because GE never asserted the patent. Readers wanting a certified chain-of-title should pull a USPTO certified abstract of title for 3,422,831, since the historical assignment images for 1967-era filings are only partly indexed online.

Verify at: USPTO Assignment Center (search patent number 3422831) — equivalent legacy endpoint: assignment.uspto.gov patent index.

Explicit gaps (stated rather than guessed)

• Reel/frame for the inventor→GE assignment: not retrieved. Under 1960s practice it almost certainly was recorded, but I will not supply a reel/frame number I did not observe.
• Correspondent of record: unknown, because no conveyance rows were returned. Signal 3 is therefore "unclear," not "not present."
• Pre-1986 paper dockets are largely absent from electronic databases, so "no assignments located" must be read as "none located in searchable sources," consistent with the prior section's caveat on litigation.
• Sivertsen's GE tenure is not independently documented in the sources reached; I assert only Straney's long GE association (US 3,064,435; US 3,233,413; US 3,422,831).

I'll search for the cited references and confirm the citation record for US 3,422,831.

Let me verify the USPTO record and dig into the identities of both cited references.

Prior Art Analysis — U.S. Patent No. 3,422,831

Patent: "Turbine Control System," Straney & Sivertsen, assigned to General Electric Co.
Filed: 1967‑02‑20 · Granted: 1969‑01‑21 · Term expired ~1969+17 → 1986‑01‑21 (record shows "Expired – Lifetime")
Confirmed record: https://patents.google.com/patent/US3422831/en (mirror of the USPTO full‑text/imaging record; the page carries the USPTO PatentCenter / Assignment links). The full authoritative text supplied in this task is taken as controlling over any search‑engine summary.

1. Scope note and one procedural caveat before the merits

The task asks for "each patent citation." On the face of US 3,422,831 there is exactly one U.S. patent citation. Its "References Cited" section reads:

UNITED STATES PATENTS
3,348,559 10/1967 Brothman et al. 137‑22 X
OTHER REFERENCES
Fluid Power News 25, The Oilgear Co., 1964, 137‑22.

Google Patents indexes this as "Citations (1)" — i.e., a single patent citation (US 3,348,559 A), with the Oilgear item carried separately as non‑patent literature. I did not auto‑correct or "fill in" additional citations; the citation set is genuinely this thin.

Discrepancies I am flagging rather than smoothing over:

• The Unified Patents portal record (https://portal.unifiedpatents.com/patents/patent/US-3422831-A) reports "Non‑Patent Literature (0)", which contradicts the printed patent's "OTHER REFERENCES" entry for Fluid Power News 25. Both cannot be right; the printed patent is authoritative, so I treat the Oilgear item as a cited reference.
• The same portal lists the priority date as 1967‑02‑19, whereas the patent/Google record shows 1967‑02‑20 (filing date). Minor bibliographic conflict; not material to the prior‑art analysis.
• The front page credits US 3,348,559 to "Brothman et al."; Google Patents attributes the assignee of that patent to Baldwin Lima Hamilton Corp. I could not independently verify the inventor list from my searches, so I report the citation exactly as the patent prints it and note the assignee separately.

2. The one patent citation — full analysis

Reference 1 — U.S. Patent No. 3,348,559

Brief description of the disclosure (US 3,348,559): An electronic governor for regulating turbine speed. It generates a digital speed‑error signal (a magnetic pickup on a toothed shaft, a reversible counter set from a high‑frequency oscillator between pulses, a shift register, and a binary resistor matrix with complementary electronic switches to convert the count to analog), and uses the complementary analog error signals to drive push‑pull valve means / a relay valve with a solenoid armature that adjusts turbine gate or steam‑valve position. It also includes gate‑position‑to‑voltage feedback (a servo loop comparing gate position voltage to a set point), an integrating means in one of three parallel signal paths, complementary analog outputs, and uses magnetic amplifiers as amplifier stages. Claims 4–6 recite the complementary error signals, the reversible counter/error‑sensing means, and the push‑pull valve means; claim 12 recites an adjustable dither winding on the magnetic amplifier.

§102 status — threshold point on dates: US 3,348,559 issued 1967‑10‑24, which is after the 1967‑02‑20 filing date of US 3,422,831. It therefore cannot be a §102(b) reference (not printed more than one year before the '831 filing). Its only §102 channel is pre‑AIA §102(e) — a U.S. patent granted on an application filed before the applicant's invention (application filed 1964‑04‑07), giving it prior‑art effect as of 1964‑04‑07. The "X"‑type marking on the printed patent is consistent with the examiner treating it as the strongest reference in the set.

Does it anticipate (35 U.S.C. §102) any of claims 1–8 of US 3,422,831?

My assessment: No claim is anticipated. The two disclosures share a field (electrohydraulic turbine valve/gate positioning with a position error signal), but the '559 reference is missing every element that defines the '831 claims. Claim‑by‑claim:

Where US 3,348,559 is relevant: as a §103 (obviousness) secondary/background reference, not a §102 anticipatory reference. Its overlaps with '831 are: (i) electrohydraulic positioning of a turbine steam valve/gate from an electrical position‑error signal (relates to claims 1 and 6's "power amplifier" element); (ii) position‑to‑voltage (position feedback) comparison (relates to claim 6's "CT … responsive to actual valve position"); (iii) complementary error signals / push‑pull valve actuation; and (iv) an integrating path that performs a rate‑shaping function (relates to the "limit the rate of change" elements of claims 3 and 7). None of these, alone or together, discloses the synchro‑transmitter/differential‑transmitter/control‑transformer architecture or the reversing‑valve/common‑amplifier/clutch/logic architecture that the '831 claims are actually directed to.

3. The non‑patent citation (for completeness)

Reference 2 — Fluid Power News 25, The Oilgear Company, 1964

Subject matter: The Oilgear Company was a long‑established maker of variable‑delivery hydraulic pumps with servovalve/servo‑piston stroking controls and integral auxiliary pumps (their catalog literature describes remote servo‑control of pump displacement and rapid reversal of a variable‑delivery pump; see contemporaneous Oilgear trade literature, e.g., the 1958–1963 Machine Design advertisements and the "High Horsepower" pump bulletin, which describe servovalve and multi‑solenoid controls on variable‑delivery pumps). The '831 patent's own FIG. 3 describes exactly this class of hardware: a reversible variable‑delivery pump with a slide block set by a hydraulic servomotor under a servovalve, constant low‑pressure supply, relief‑valve regulation, and a transducer (LVDT) slide‑block position feedback.

§102/§103 status: As a product/trade publication it is a §102(b) printed publication candidate (dated 1964, more than one year before the 1967‑02‑20 filing). However, it discloses only the hydraulic pump/servovalve sub‑combination, not a turbine control system, and certainly not the synchro control channel, CDX overspeed modification, diode gating, clutches, or logic means. It anticipates no claim of US 3,422,831. Its relevance is confined to the "power amplifier"/"reversible variable delivery pump … servomotor … servovalve" elements recited generically in claims 1 and 6 — i.e., it evidences that the hydraulic power stage was conventional (a §103 background reference, and the reason the examiner cited it with the 137‑22 classification).

4. Bottom line

1. Citation set on US 3,422,831 is a single patent reference (US 3,348,559) plus one non‑patent reference (Oilgear Fluid Power News 25, 1964). No other patent citations exist on the face of the patent.
2. The most relevant prior art in that set is US 3,348,559 A (Brothman et al. / Baldwin Lima Hamilton), filed 1964‑04‑07, granted 1967‑10‑24.
3. Neither reference anticipates any of claims 1–8 under §102. Both are best characterized as §103/background art: '559 for the electronic error‑signal generation, position feedback, complementary/push‑pull valve actuation and integrating (rate) path; the Oilgear publication for the conventional reversible variable‑delivery pump and servovalve power stage.
4. Because US 3,348,559 issued after the '831 filing date, its only §102 theory is §102(e) with an effective date of 1964‑04‑07; it cannot be a §102(b) reference.

Caveats (stated explicitly)

• My searches did not return the front‑page inventor names of US 3,348,559; I report the inventor attribution exactly as the '831 patent prints it ("Brothman et al.") and separately note Google's assignee attribution.
• The Google Patents "Similar Documents" list for '831 (e.g., US 3,407,826 "Electrohydraulic overspeed control system for a reheat steam turbine"; US 3,709,626 "Digital analog electrohydraulic turbine control system"; US 3,198,954 "Overspeed anticipation device") contains art that arguably sits closer to the synchro/overspeed subject matter — but none of these was cited against '831, and US 3,407,826 (granted 1968) post‑dates the '831 filing. I therefore did not treat them as "citations for 3,422,831." If a broader §102/§103 validity search is wanted, those are the first documents to pull.
• I did not use Westlaw/Lexis or the USPTO's image file wrapper tooling directly; the citation record above is taken from the patent's printed front page / its USPTO‑mirrored full text, cross‑checked against the Google Patents and Unified Patents bibliographic records.

I'll analyze obviousness under § 103 using the prior-art citations surfaced on this patent's page, plus the similar-documents/related-art listings. Let me ground the key references first.

Now let me ground the other related-art references that would be candidates for combination.

Obviousness Analysis — U.S. Patent No. 3,422,831 under 35 U.S.C. § 103

Scope note: This builds on the prior summary and litigation sections and does not repeat them. The patent's priority is the Feb. 20, 1967 filing date (per the patent's own front matter), so pre‑AIA § 103(a) governs, analyzed under the Graham v. John Deere factors. Because a validity challenge would be adjudicated today, KSR Int'l v. Teleflex governs how the "motivation to combine" is evaluated (flexible TSM, "obvious to try," and "combination of familiar elements according to known methods"). The patent is expired (≈1986), so this is a hypothetical/defensive analysis, not a live AIA post‑grant proceeding.

I grounded the reference content I could retrieve; where retrieval failed I say so explicitly rather than characterize content.

1. The prior-art inventory actually on this page

The page's "Prior Art" resources fall into three buckets:

A. Examiner-cited U.S. patent (the only patent citation)

B. Examiner-cited non-patent literature

C. "Similar Documents" / related art on the page — date-filtered for 103 eligibility

Only documents with a pre‑Feb.‑1967 date can be § 102/§ 103 prior art against '831. Sorting the page's similar-documents list:

Usable (pre‑1967):

• US 1,973,443 (1934) Apparatus for governing steam turbines
• US 2,386,110 (1945) Turbine control apparatus
• US 2,658,122 (1953) Propeller pitch stop system
• US 2,678,177 (1954) Manual booster and automatic pilot servo system
• US 2,690,192 (1954) Pilot-operated control valve for hydraulic servo systems
• US 2,871,660 (1959) Remote control system
• US 2,908,826 (1959) Non-linear speed and load governor for alternators
• US 2,980,188 (1961) Combined feathering and pitch lock system
• US 2,995,190 (1961) Impellers
• US 3,018,988 (1962) Electro-hydraulic jack device…
• GB 989,227 (1965) Control mechanism for a driving unit…
• US 3,198,954 (1965‑08‑03) Overspeed anticipation device
• US 3,286,600 (1966) Electronic engine controllers
• US 3,340,883 (granted 1967‑09‑12) Acceleration, speed and load control system with redundant control means (Peternel) — a GE patent; its filing predates Feb. 1967 and it is expressly relied on as a speed/acceleration‑control disclosure in US 3,709,626.

NOT usable as prior art (post‑date the 1967 filing): US 3,339,696 (1968), US 3,407,826 (1968‑10‑29), US 3,438,201 (1969), US 3,709,626 (priority 1971), GB 1,244,160 (1971), GB 1,345,589 (1974), US 3,901,274 (1975), US 3,986,364 (1975 filing), US 4,082,115 (1976 filing), US 4,140,075 (1979), SE 409,232 (1979), US 6,955,113 (2005). These are useful only as evidence of what was conventional in the field later, or as corroboration of a design trend. They cannot be combined into a 103 rejection of '831. I note this because the page presents them together; a careless analysis would improperly cite US 3,709,626 or US 3,986,364 (both GE) as if they were prior art.

2. The decisive leverage: the patent's own admissions

The strongest 103 material is not an external reference — it is the specification's Background. '831 expressly admits, as known art:

1. Two complete electrohydraulic control systems for ahead and astern valves, "each control employ[ing] its own reversible variable delivery hydraulic pump driving a constant displacement hydraulic motor which in turn operates a set of valves." (col. 1)
2. That this duplication "adds greatly to the cost."
3. DC electrical signals with operational amplifiers, valve position feedback, rate-of-change feedback, and speed feedback were all known techniques — criticized only as "relatively expensive" and "accuracies which are often not warranted."
4. The rack-and-pinion direction reversal and its alternatives ("a reversing lever for one valve connection, or … an additional gear mesh on one output side of gearbox 24") — mechanical reversing of one output is stated to be old.
5. AND/OR logic modules and on-off limit switches: "Design of such circuits is conventional and well known."

Under § 103 these admissions are prior art for all that they describe. That collapses the factual gap between the admitted two-unit arrangement and claim 1's "power amplifier means common to portions of the first and second control means."

3. Claim-by-claim obviousness contentions

Claim 1 — the system claim

Motivation / rationale: KSR holds that a problem known in the field — here the cost of duplicating a complete pump‑motor‑valve power train — supplies a reason to modify. The patent itself frames the invention as cost-driven. Sharing one pump, one motor, one amplifier, and one gearbox between two valve loops, with clutches to select which loop the common amplifier drives, is the predictable engineering answer and achieves nothing more than the expected result of removing redundant equipment. "Duplication to reduce cost" is a design-economics choice, not an inventive contribution.

Note on the "opposite senses" limitation: the patent's own text concedes that inverting one output is a mere mechanical selection among old equivalents, which weakens any argument that this element is inventive.

Claim 2 — disengageable clutches, actuated by valve-position-responsive logic

Clutches to couple/decouple a driven member are ancient; limit-switch-driven actuation is admitted conventional. The only possible quibble is the timing (actuate the astern clutch at ~50% ahead flow). That is a result-effective variable optimized by routine testing to balance boiler steam-flow limits against reversal speed — obvious to try, with no asserted criticality and no unexpected result.

Claim 3 — common AC input for both signals + rate limiting

Producing two positioning signals from one AC source is exactly what a synchro transmitter with two follow-up channels / a differential transmitter does — standard synchro practice, and the patent's FIG. 4/FIG. 5 arrangement (one CX rotor, function generators 21/22 driving separate CX rotors) is a routine application. Rate limiting of a servo output is a routine control expedient (a rate limiter or reduced excitation of a two‑phase motor, as the patent itself describes at gearset 89 + fast rate controller 86).

Claim 4 — gating means admitting only one positioning signal at a time

Diode/rectifier gating (a "diode switch," a highest/lowest-wins selector) is a bog-standard analog logic element of the era; US 3,286,600 (1966) Electronic engine controllers and the general analog-computing art show signal-selector gates. The patent admits the diode switch is a selection device built from conventional parts.

Claim 5 — overspeed-responsive synchro differential (CDX) in the claim‑1 context

See claim 6 analysis; the same reference mapping applies, plus US 3,198,954 (Overspeed anticipation device, 1965) for speed-responsive modification of a control signal and mechanical overspeed relays (admitted well‑known: "oil‑operated spring‑loaded pistons… from the turbine shaft‑driven centrifugal pumps").

Claim 6 — the AC synchro channel (CX + CDX + CT)

Motivation: the specification's own premise — that DC operational-amplifier summing was expensive and over-accurate for the application — supplies the reason to substitute AC synchro summing (the patent's stated advantage: "closed loop control … by rotation of the relative winding positions in relatively inexpensive AC synchro control devices"). Trading precision for cost by swapping a known signal-transmission technology for another known one, where both give closed-loop position control, is the paradigm of obvious design choice (KSR: "a combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results").

Claim 7 — rate limiting defeatable for emergency (fast) valve movement

Selectable fast/normal rates via a pushbutton and a controller (fast rate controller 86, pushbuttons 87/88) is a routine operator-selectable limit. A "means to render the limiting means ineffectual" is a switch — trivially obvious once rate limiting (claim 3) is present.

Claim 8 — spring-biased valve mechanism + overspeed clutch disengagement

Spring-return / spring-closing steam valves are the safety baseline of turbine practice (Brothman's spring-loaded valve; US 1,973,443; US 2,386,610). Speed-responsive trip that releases a coupling so springs close the valve is the classic overspeed trip — US 3,198,954 (Overspeed anticipation device), plus the admitted centrifugal-pump/spring-piston overspeed relays. Combining an overspeed trip with a clutch (already present per claim 2) is a predictable safety aggregation.

4. The motivating factors, stated compactly

1. Cost / redundancy elimination — expressly the problem the patent sets out to solve; the patent admits the prior art duplicated an entire electrohydraulic power train.
2. Simplicity and reliability — a single common amplifier, single pump/motor/gearbox, and conventional on‑off logic.
3. Substitution of known signaling technologies — AC synchros for DC operational-amplifier summing, at a stated intentional sacrifice of accuracy the patent says was "not warranted."
4. Known safety requirement — overspeed protection via a differential transmitter and a clutch/trip, using admitted overspeed relays.
5. Mechanical equivalence — direction reversal by gear mesh/rack-and-pinion/reversing lever, expressly conceded as interchangeable.
6. Single control input — operating both valve sets from one console lever is an ergonomic/marine-handling requirement, and one synchro source feeding two channels is standard.

No reference appears to teach away, and the field was moving in the same direction (later GE patents — US 3,709,626, US 3,986,364, US 4,082,115 — refine rather than depart from this architecture, corroborating that the approach was the natural next step, though those documents cannot themselves be cited as prior art).

5. The best formulations of rejection

Formulation A (primary, single reference + admissions):
Brothman '559 in view of the applicant's admitted prior art (the two separate electrohydraulic valve control units, each with reversible variable-delivery pump + constant-displacement motor), optionally with the Oilgear Fluid Power News 25 pump disclosure as evidence the hydraulic power train was catalogue hardware. Rationale: replace Brothman's single servo loop's duplication with one common amplifier/motor driving both valve loops through clutches, reversing one output by gear mesh, and gating one error signal at a time — a predictable cost-driven combination.

Formulation B (synchro channel):
The '831 Background's admitted DC operational-amplifier art in view of the standard synchro (CX/CDX/CT) art and US 3,198,954. Rationale: substitute an AC synchro summing channel for the DC summing channel to reduce cost, using the differential transmitter for its known function of mechanically modifying a reference signal, and the mechanical overspeed relay for the overspeed input.

Formulation C (claims 2, 7, 8):
Brothman '559 + US 3,198,954 + spring-return valve art (US 1,973,443 / US 2,386,610) + clutch art. Rationale: add a speed trip to release a coupling and let springs close the valves; defeat the rate limiter to speed emergency response.

6. Weaknesses in the 103 case (stated fairly, since this is a validity analysis)

• Claim 1's "common power amplifier means" is where an infringer would focus its non-obviousness argument: prior art of record does not literally show one pump/motor shared between two opposed valve loops with clutched outputs, so the analysis must rest on the cost-motivation + admitted-art combination rather than direct disclosure. The admissions make that combination strong, but a patentee would argue the common-amplifier-plus-clutch-overlap control scheme (switching closed-loop feedback from the closing valve to the opening valve mid-maneuver) is an architecture, not a mere aggregation.
• Claim 6's CDX-for-overspeed must be supported as the plain function of a differential synchro; the "proportional reduction" behavior is arguably inherent in proportional rotor displacement, which helps the obviousness case but the specific use with a turbine overspeed relay is the point of novelty to attack.
• Secondary considerations: none are recited or evidenced on this page (no unexpected-result data, no nexus evidence of commercial success). Absent objective indicia, the Graham factor 4 cuts against patentability.
• I could not inspect the full text of Brothman '559 or of Fluid Power News 25; my characterization of Brothman comes from the retrieved abstract/claim excerpts (electronic governor; position-to-voltage gate feedback; hydraulic servo loop; push-pull valve means) and the page's own citation of it in class 137‑22. The Oilgear NPL content is unverified — I flag that rather than assert what it says.

7. Confidence

• High that claim 1 is vulnerable under § 103 as a cost-driven combination of admitted prior art (two duplicated control units) with routine logic and mechanical reversing, and that claims 2–5, 7–8 are vulnerable as combinations of conventional elements.
• Medium-high on claim 6, contingent on the CDX-overspeed use being treated as the known function of a differential synchro plus an admitted mechanical overspeed relay.
• Explicit gap: I could not verify the Fluid Power News 25 disclosure or the full Brothman '559 specification; the analysis of those two examiner-cited references is based on partial retrieval and should be confirmed against the documents themselves.