US 3424055

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

Let me check for any litigation or CAFC docket activity involving this patent number.

Search scope and result

I searched for the specific literal string 3424055 / US3424055 / 3,424,055 and did not substitute or broaden to similar numbers. Findings below are drawn from the Google Patents record (which mirrors USPTO bibliographic data) and the granted patent PDF at patentimages.storage.googleapis.com.

CAFC 2026 dockets: no results. I found no Federal Circuit appeal, district court case, ITC action, or PTAB proceeding involving US 3,424,055. This is the expected outcome — see "Status" below. I want to be explicit that this is a negative search result, not affirmative proof of absence; I could not query PACER/CM-ECF or the CAFC docket system directly through the available tooling.

Identifier-collision warning (per your strict-interpretation rule): two unrelated hits share the digits "3424055" and must not be conflated with this patent:

• A Norwegian patent document cited as "NO 3424055 A" (1994) in the reference list of US 9,783,440 — a different national doc number.
• A Florida LLC's FEI/EIN "87-3424055" in a 2026 annual report.

Bibliographic summary — US 3,424,055

Prior art cited (4): US 1,442,659 (Groene, 1923); US 1,794,361 (Armitage et al., 1931); US 3,118,345 (Bullard, 1964); US 3,177,775 (Alisauskis, 1965). Cited by: 15–18 later documents, the largest cluster being Harold D. Cook's shrink-fit tool-holder family (US 4,818,161; 4,971,491; 5,583,494; 5,311,654; etc.).

Abstract (as recorded)

A rotary tool holder for tools having conical shank portions is adaptable either to the large American A.S.A. cone or the slender Morse cone, by means of an adaptor whose outer contour is that of the American A.S.A. cone and that has an inner socket to receive a Morse cone. A rod extends through the spindle and is urged away from the cone by a spring whose force varies inversely as the distance of the rod end from the cone. A large cone is attached to the rod end by a short extension which compresses the spring to exert relatively large force on the rod; alternatively a slender cone is attached to the rod end by a longer extension so that the spring force is reduced upon the slender cone.

The single claim, in plain language

US 3,424,055 has one claim, and it is independent — there are no dependent claims. It recites a machine tool holder combining:

1. A rotary spindle with a frusto-conical socket at one end.
2. A draw rod movable along the spindle axis.
3. Spring means biasing the rod axially away from the socket end — i.e., the spring is the tightening element (drawbar pull), not the releasing element.
4. A hydraulic jack that, when actuated, engages the rod and drives it toward the socket end, i.e., in the tool-releasing direction, working against the spring.
5. An adaptor whose outer frusto-conical surface matches the spindle socket, and which contains a coaxial frusto-conical socket of substantially smaller solid angle than the spindle socket (the A.S.A./Morse dual-taper idea). The adaptor is releasably secured in the spindle socket.
6. First interconnecting means — the short-extension coupling (part 35/36) used to attach a tool directly in the spindle socket when the adaptor is not used.
7. Second interconnecting means — the longer-extension coupling (part 39/36) used when the adaptor is used, arranged so that with the adaptor the rod sits farther from the spindle end and the spring is less compressed.
8. The functional result clause: because the spring exerts more force when compressed than when extended, the normal force on the tool shank surface is substantially the same whether or not the adaptor is used.

Why that geometry works (specification logic): the Morse taper (≈5%) is self-locking and needs little drawbar force to hold, but a lot to release; the American A.S.A. taper (≈29.17%) is the opposite. The adaptor's greater effective length (extension length b > a) means the draw rod reaches its tightened position in a more retracted position, leaving the spring less compressed — automatically delivering the lower drawbar force the self-locking Morse cone requires, without any change to the hydraulic/spring hardware.

Claim-drafting note: the clause "such that the rod is farther from the end of the spindle and the spring means is less compressed when the adaptor is used than when the adaptor is not used" is grammatically loose — the "than when the adaptor is not used" comparator arguably attaches only to "less compressed." On the specification's own geometry (spring compressed further = rod pushed further forward toward the nose), both readings do in fact agree, but the phrasing is worth flagging if you are construing the claim.

Status and litigation exposure

The record lists anticipated expiration 1986-01-28 and status "Expired – Lifetime." A US patent from a 1964 priority date, expired in 1986, is not capable of being asserted in 2026 — no live infringement claim, no ITC exclusion action, and no basis for a CAFC appeal. The complete absence of CAFC 2026 or PTAB activity in my search is therefore consistent with the record rather than surprising. The only continuing relevance of this document today is as prior art in tool-holder art (notably the Cook shrink-fit family cited above) and as a teaching reference on dual-taper spindle adaptors.

Points of uncertainty — flagged explicitly

• No primary USPTO/CAFC database confirmation. I could not open USPTO Patent Center, PACER, or the CAFC docket directly. Bibliographic data above comes from the Google Patents rendering of the US grant; treat the assignee and current-assignee strings as recorded metadata rather than verified chain of title. Note that Google Patents shows two assignee strings ("GENEVOISE D'INSTRUMENTS DE PHYSIQUE SOC" and "GENEVOISE INSTR PHYSIQUE") which I read as name variants of one Swiss entity, but I have not confirmed a corporate-history source for that.
• "Solid angle" vs. taper percentage. The specification calls 29.17% and 5% "solid angles." These are standard taper ratios/diametral tapers (A.S.A. ≈ 3.5 in/ft; Morse ≈ 5%), not angles in degrees. This looks like a translation artifact from the French/Swiss original and should not be read as a plane-angle or steradian measure.
• OCR artifacts in the source. The transcribed text contains garbles ("oi." the sleeve," "cornpresses," "tudownloads," "iix," "antightening") and the claim as printed shows "the 4rod" / "With." I have quoted intent, not the OCR noise. In one place the description text reads "removable sleeve 24" where the sleeve is consistently numbered 14 elsewhere (24 is the hydraulic jack) — an apparent typographical error in the original patent, which I have not auto-corrected.
• Google Patents "Definitions" block (the bulleted, machine-paraphrased language) is an auto-generated summary, not claim text or authoritative specification language. I relied on it only where it matches the granted text, which it does throughout.

I'll research litigation involving US patent 3424055 using the sources you specified.

Let me check the specific litigation databases you mentioned.

Litigation Search: US Patent 3,424,055

Bottom line

I found no evidence of any litigation involving US Patent 3,424,055 — no district court case, no CAFC appeal, no PTAB proceeding (IPR/PGR/CBM), and no ITC Section 337 investigation. This is consistent with the patent's age and status: it issued January 28, 1969, and its term expired January 28, 1986 (Google Patents records it as "Expired – Lifetime," anticipated expiration 1986-01-28). A patent that expired four decades ago cannot support a live infringement action, so the absence of indexed litigation is expected rather than surprising.

What I searched and what I found

False positives I want to flag (so you don't mistake them for this patent)

1. EP 0167883 B1 (Siemens) lists priority "DE 3424055" — that is a German application number for an x-ray high-voltage regulator, unrelated to the US patent. (Source: patentimages.storage.googleapis.com / EP0167883B1.pdf)
2. A Florida LLC annual report shows FEI Number "87-3424055" for CESCARDIM LLC — an IRS employer ID, not a patent.
3. Myco Industries, Inc. v. BLEPHEX, LLC, IPR2020-01738, Exhibit 1039 contains a prior-art search-string listing a long string of patent numbers that includes "3424055" (e.g., ... "3397615" | "3424055" | "3557419" ...). This is a patentability search query, not litigation asserting US 3,424,055. The IPR involves a different patent (the '365 patent family), and US 3,424,055 appears only as one number inside a keyword string.

Note also that the Docket Alarm / PTAB documents I surfaced referencing litigation (Stratasys v. Bambu, Jawbone Innovations v. Amazon/Google/Sony, etc.) involve entirely different patents; I am not counting them.

Caveats on confidence

• Pre-1986 enforcement is not well covered by the online docket aggregators you named. PACER coverage is largely electronic from the late 1980s onward; Unified Patents' caselist and Docket Alarm focus on modern (mostly post-2000) patent suits. A 1970s–1990s infringement suit on a now-expired patent could in principle exist in paper archives without appearing in any of these databases.
• I also hit a tool-step limit, so I could not exhaustively verify via a direct PACER query, a Westlaw/Lexis docket search, or the Federal Circuit's historical opinions archive. Those are the places I'd check if you need a definitive negative for the 1969–1986 window.
• I did not auto-correct any identifier; I treated "3424055," "3,424,055," and the assorted non-patent numbers literally.

Recommendation

If you need a defensible "no litigation" statement for this patent, run a paid docket search (Lexis/Westlaw/Docket Navigator) covering all federal districts for the years 1969–1986, plus a CAFC/CCPA historical opinion search, since the free sources I used are unlikely to have captured any enforcement activity from that era. Based on everything currently indexed and publicly searchable, however, no litigation involving US Patent 3,424,055 is known.

Proceedings overview

Total AIA trial proceedings on file for US 3,424,055: zero. The structured PTAB block (USPTO Open Data Portal) returns no AIA trial proceedings — no IPRs, no PGRs, no CBMs — and no proceeding appears in the PTAB E2E / PTAB Decisions record or in any indexed source; the breakdown is therefore 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution-denied. The defensive posture for a defendant is not "hardened by survival" and not "claims canceled" — it is the more basic point that US 3,424,055 granted 1969-01-28 and expired 1986-01-28, so there is no claim scope left for anyone to assert and no PTAB proceeding to run.

No proceedings to report

The absence here is not the usual "quiet patent" absence. It is structural, and it is worth being precise about why, because a defendant receiving a demand letter citing this patent needs to know that the PTAB route was never the relevant route:

• Statutory timing. The America Invents Act created the IPR/PGR/CBM regimes in 2011–2012, with IPR available for petitions filed on or after 2012-09-16, PGR for patents with an effective filing date on or after 2013-03-16, and CBM limited to patents claiming a "financial product or service" (Part 42 / AIA §§ 6, 18). US 3,424,055 has a priority date of 1964-12-04 and a filing date of 1965-11-12 — roughly forty-eight years before those regimes existed.
• No remaining term. Per the structured data, the anticipated expiration is 1986-01-28 (17 years from the 1969-01-28 grant under pre-URAA law). The patent's legal status is "Expired – Lifetime." The only claim — claim 1 — lapsed with the term. There is no claim whose validity a PTAB panel could cancel or sustain.
• Search results. Web search on the patent number returned only the patent's own documents (the Google Patents PDF of the specification) and unrelated hits for the digit-strings 342, 405, and 3,424,055 in other patents (e.g., U.S. 7,089,342 and U.S. 9,355,405 in Mondis and Agila proceedings). I found no reference to any AIA trial involving US 3,424,055. Flagging clearly: if a defendant's counsel has seen a proceeding number purporting to involve this patent, that number is almost certainly a mis-transcription of one of those digit-string collisions, and it should be verified in PTAB E2E before it is cited in any filing.

The 15+ "Cited By" entries on the Google Patents page (e.g., US4412766 to Waldrich Coburg, the Cook shrink-fit series US4818161/US4971491/US5311654, US5715735 to First Tool Corp.) are forward citations in later patents — they are not PTAB proceedings and do not indicate any challenge to the '055 patent.

Strategic summary

Claim status. US 3,424,055 has exactly one claim (claim 1 — a machine tool holder with a frusto-conical spindle socket, an axially movable rod, spring means biasing the rod away from the socket end, a hydraulic jack for tool release, and a removable adaptor whose inner frusto-conical socket has a substantially smaller solid angle than the spindle socket, arranged so that the spring is less compressed — and exerts less force — when the adaptor is used, such that the normal force on the tool shank is substantially the same either way). It is neither canceled, nor sustained, nor untested in the IPR sense — it is expired. There is no surviving claim set to work around and no live claim to invalidate. Analogous family members lapsed on their own national schedules: GB1124363A (published 1968-08-21), DE1245250B (published 1967-07-20), CH427455A (published 1966-12-31).

Estoppel landscape. 35 U.S.C. § 315(e)(2) estoppel is inapplicable — it attaches only to a petitioner that has instituted an IPR and reached final written decision, and there is no such petitioner here. Similarly, there is no § 325(e) PGR estoppel and no § 328 estoppel. That is small comfort in the abstract but irrelevant in practice: estoppel bars a defense; the unavailability of any live claim bars the case. For a defendant, the operative "prior art ground still available" is everything — including the four references the examiner already considered (US1442659 Groene; US1794361 Armitage et al.; US3118345 Bullard; US3177775 Alisauskis) — because there is nothing left to litigate.

Pattern signals. None. There is no repeat petitioner, no PTAB appeal history, no defensive aggregator (Unified Patents or similar) in the chain, and no Federal Circuit docket because no FWD issued. The patent owner of record — Genevoise d'Instruments de Physique (Société Genevoise d'Instruments de Physique, Geneva) — a Swiss precision-instrument and machine-tool maker, has no AIA trial history associated with this patent.

Recommended next steps

• If you are a defendant and a demand letter or complaint cites US 3,424,055, do not spend a PTAB budget. There is no PTAB activity to leverage and no claim left to reach. Check the face of the patent: "Expired – Lifetime," anticipated expiration 1986-01-28. Confirm status for yourself at USPTO PatentCenter and the Global Dossier / Espacenet record, then move to a standing/mootness and damages-period argument (27 years have elapsed since expiration; § 286's six-year damages lookback cannot reach any pre-expiration conduct that is still actionable) rather than an invalidity defense.
• There is no FWD to link to, no institution decision deadline, no oral hearing date, and no statutory one-year trial clock running. If opposing counsel represents otherwise, ask for the proceeding number and the PTAB E2E link; then check it against the digit-string collisions identified above (US 7,089,342 / Mondis; US 9,355,405 / Agila; IPR2021-00720).
• Verify the number literally. Per operating instructions I have not auto-corrected any identifier. US 3,424,055 is a 1969-issued, 1986-expired, single-claim mechanical tool-holder patent. If the assertion document uses a different number, the analysis above does not transfer and the correct patent should be re-run through the ODP structured PTAB data before any position is taken.
• The absence of PTAB activity is not a signal of a strong untested patent here. The usual inference — "well-asserted patents eventually attract IPRs" — is inapplicable to a patent that expired before the AIA existed. Treat the absence as a date problem, not a merits signal.

Sourcing note: the proceeding list is taken from the structured "PTAB proceedings on file" block (USPTO ODP, most recent ingest), which reports no AIA trials; no contradicting proceeding was found via web search on 2026-09-30. Where the record is silent I have said so rather than inferring an FWD, panel, or settlement.

I'll research the assignment record for US 3,424,055 across the sources you specified.

Let me search the assignment databases and corporate history sources directly.

Now let me look for the inventor and any recorded assignment/chain-of-title data.

Ownership & Assignment Analysis — US 3,424,055

Data-access caveat up front (read this first): I could not complete a live query of the USPTO Patent Assignment Center (assignmentcenter.uspto.gov / assignment.uspto.gov) or PEDS before exhausting my tool budget on this task. Everything below is therefore built from (a) the Google Patents legal-events log for US3424055A, which mirrors USPTO bibliographic/assignment-event metadata, and (b) published corporate-history sources for the original assignee. I have not fabricated any reel/frame number. Where I say "no record," it means "no record surfaced in the sources I could reach," not "certified absent from the USPTO register." I flag exactly where a paid/direct Assignment Center query must close the gap.

Inventors

• Single-inventor patent, consistent with it being an in-house design contribution by a SIP engineer rather than a joint-development artifact.
• Rollat is a repeat SIP inventor in the same tool-clamping art — he is named on the priority-adjacent SIP case GB 990,353 A ("Quick action device for securing a tool to a machine tool spindle," priority 1962-09-24, assignee "Genevoise Instr Physique"), which is cited in the family literature. This corroborates that he was a continuing SIP employee working on spindle/tool-clamping hardware, not a one-off filer.
• Unusual-pattern check (inventor departure preceding a fire-sale): Not present / unclear. Nothing in the record suggests Rollat assigned away or left before filing. Note the asymmetry however — because the patent predates the NPE era entirely, an inventor-departure signal would be meaningless here even if it existed; SIP held the invention as an operating-company asset (see below).
• Uncertainty: I could not confirm Rollat's exact job title, dates of employment, or whether he appears on other later SIP US grants (e.g., via a PEDS inventor-name query). That is a verifiable next step.

Original assignee

Société Genevoise d'Instruments de Physique ("SIP") — Geneva, Switzerland. Named on the face of the patent as assignee (recorded variant strings: "GENEVOISE INSTR PHYSIQUE" / "GENEVOISE D'INSTRUMENTS DE PHYSIQUE SOC" — read as name variants of one entity, see the earlier bibliographic section).

Line of business: Operating manufacturer, not a holding/licensing vehicle. Founded 1862 in Geneva as a maker of scientific apparatus; moved into precision metrology and machine tools. Its 1921 "machine à pointer" (MP) jig borer made it one of the world's most respected machine-tool builders; it also produced working standard metre bars for national bureaus of standards and was a global reference in precision machining. (HLS/DHS corporate history; City of Geneva industrial-history page)

Did SIP ship a product embodying the claims? Yes — SIP's spindle/tool-clamping hardware is the direct commercial embodiment. The patent describes a dual-taper (American A.S.A. ≈29.17% outer socket + internal Morse ≈5% adaptor) hydraulic-release / spring-draw drawbar — precisely the tooling interface on SIP jig borers and precision milling spindles. SIP was producing these machines in volume throughout the period (≈1,200–1,600 employees in 1969). (Bulletin technique de la Suisse romande, 1962; Science Museum Group)

Current status — operating → distressed → defunct as an independent entity:

• 1990: moved from Plainpalais to Satigny.
• Late 1990s: severe financial distress under principal owner Michel Suchet (debt, creditor mortgage, failed rescue talks with Starrag). (Le Temps)
• Early 2000s: insolvency / bankruptcy ("Konkurs") proceedings; the University of Kansas describes "a string of bankruptcy filings in the early 2000s." (KU Physics)
• 2005–2006: StarragHeckert (Starrag Group) acquired SIP's assets out of insolvency, retaining ~40 of ~80 staff at Geneva. (NZZ)
• 2016: the Satigny plant closed.
• Now: no longer an independent operating company; the "SIP" brand/technology sits within the Starrag Group.

Caution on "1973 merger": one source (CHSI eMuseum) states SIP "merged with Hauser and DEA" in 1973. I could not corroborate this as a corporate merger (it more plausibly reflects a joint marketing/sales arrangement). Treat as unverified.

Assignment timeline

Finding: I identified no recorded post-issuance assignment for US 3,424,055 in any source I could reach. The Google Patents legal-events log shows only lifecycle events, with no assignment/reel-frame entries:

Because SIP is named as assignee on the face of the grant, title presumably vested in SIP at issuance (either by applicant-as-assignee filing or by an inventor→SIP assignment recorded in the 1965–1969 window). I could not retrieve that reel/frame, and I will not invent one. The substantive point is that no post-issuance conveyance appears anywhere in the record.

Consequence of the 1986 expiration: US 3,424,055 expired 1986-01-28 — roughly two decades before SIP's bankruptcy-era asset sale. There would have been no economic reason to record any transfer of this patent during the 2005–2006 StarragHeckert asset acquisition, and none appears. So the corporate-succession story below is context about the owner, not a recorded assignment of this patent.

To close the gap definitively, run a direct Assignment Center query by patent number 3424055 (and by application 507810), plus PEDS/ODP: assignmentcenter.uspto.gov and assignment.uspto.gov/patent/index.html. If those return nothing, the correct finding is "no recorded assignment chain — only the original holder."

Timeline diagram

(Corporate/custody history. Only 1965, 1969 and 1986 are USPTO-recorded events; the rest are published corporate history and are not USPTO assignments.)

timeline
    title Ownership and custody of US 3424055
    1862 : SIP founded in Geneva
    1964 : Swiss priority application filed
    1965 : US application filed by SIP
    1969 : US patent issued to SIP
    1986 : Patent term expires
    1990 : SIP moves to Satigny
    2005 : SIP insolvency proceedings
    2006 : StarragHeckert acquires SIP assets
    2016 : Satigny plant closed

NPE / troll-pattern signals

Identifier-collision restatement (carried forward, not repeated in full): do not conflate US 3,424,055 with the Siemens x-ray German application number DE 3424055 (priority of EP 0167883 B1), the Norwegian document "NO 3424055 A," the Florida FEI/EIN 87-3424055, or the patent-number search string containing "3424055" in IPR2020-01738 Exhibit 1039. None of these is this patent or an assignment of it.

Verdict

Insufficient data (no post-issuance records — only the original holder).

There is no recorded assignment chain for US 3,424,055: the Google Patents legal-events log shows only filing (1965-11-12), grant (1969-01-28) and anticipated expiration (1986-01-28), with no reel/frame entries, and no corpus I could reach shows any conveyance out of the original assignee. The holder of record throughout was Société Genevoise d'Instruments de Physique, an operating Swiss machine-tool and metrology manufacturer that shipped the claimed dual-taper spindle hardware. SIP's later insolvency and the 2006 StarragHeckert asset purchase occurred ~20 years after the patent expired (1986-01-28), so they are corporate-succession context rather than a transfer of this patent. No NPE or troll-pattern signal is supportable on this record, and the patent has been incapable of assertion since 1986.

Verify at: USPTO Assignment Center — search patent 3424055 · legacy Assignment Search · [PEDS/ODP for application 507810]. If those confirm zero records, the above "insufficient data / original holder only" verdict is final and no further NPE analysis is warranted.

Explicit residual uncertainties: (1) I did not directly query the Assignment Center, so a pre-1969 inventor→SIP assignment reel/frame may exist un-retrieved — I have not guessed it. (2) I did not verify Rollat's employment tenure or confirm the SIP "1973 Hauser/DEA merger" claim. (3) Swiss insolvency records for SIP's patent portfolio were not examined; given the 1986 term date, I do not expect any US-recorded transfer of this patent, but that is an expectation, not a verified absence.

I'll research the cited prior art for US 3,424,055 via multiple searches.

Let me retrieve details on each of the four cited references.

Prior-Art Analysis — US 3,424,055

Search performed: literal query for 3424055 / US3424055 / 3,424,055, resolving to the Google Patents record (mirroring USPTO bibliographic data) and the granted PDF at patentimages.storage.googleapis.com/.../US3424055.pdf. No similar-number substitution was made. I did not have direct access to USPTO Patent Center / Patent Full-Text search, so citations below are grounded in the Google Patents citation table plus the underlying reference PDFs where retrievable.

Key structural fact driving this analysis: US 3,424,055 has exactly one claim, and it is independent — there are no dependent claims. So every § 102 question in this patent collapses to a single inquiry: does a given reference disclose all elements of claim 1?

The four references cited on the face of US 3,424,055

Reference-by-reference

1. US 1,442,659 — Groene, "Milling-machine spindle"

• Full citation: US 1,442,659 A, W. F. Groene, "Milling-machine spindle," filed 1920-06-10, granted 1923-01-16, assignee R. K. LeBlond Machine Tool Co.
• Description: An early milling-machine spindle patent from the LeBlond stable (Groene is a prolific LeBlond inventor per DATAMP's assignee listing). Classified in USPC 279/103 (chucks/sockets with tool retention). It is a foundational, purely mechanical spindle/drawbar-era reference predating powered drawbars.
• § 102 analysis vs. claim 1: Does not anticipate claim 1. It can only speak to generic elements (a) a rotary spindle with a conical socket and (b) an axially movable tightening rod. It contains no spring means biasing the rod away from the socket (element c), no hydraulic jack (element d), no dual-taper adaptor of substantially smaller solid angle (element e), and therefore none of the "first/second interconnecting means" or the equal-normal-force functional clause (elements f–h). It is § 102(b) art (granted >1 year before the 1964-12-04 priority date) but is relevant only as background for the spindle/drawbar environment.
• Confidence note: I could retrieve the citation metadata but not the full text/claims of US 1,442,659. The "no anticipation" conclusion rests on the reference's title, date, and classification; treat it as lower-confidence than the two references below that I read in full.

2. US 1,794,361 — Armitage et al., "Milling-machine spindle and tool"

• Full citation: US 1,794,361 A, J. B. Armitage, B. P. Graves, E. J. Kearney, L. F. Nenninger, "Milling-machine spindle and tool," filed 1927-03-25, granted 1931-03-03, assignees Kearney & Trecker Corp., Brown & Sharpe Mfg., Cincinnati Milling Machine Co.

• Description (from the granted text): A horizontal milling spindle 1 with a bore comprising a relatively steep tapered portion 2, a straight cylindrical portion 3, an axial bore 4, and an enlarged rear bore 5. A sleeve 6 in the rear bore carries a threaded rod 8 that runs through the spindle to the nose and is fitted with a larger threaded portion 9 and a smaller threaded portion 10. An arbor 11 has a tapered shank 11c mating with steep taper 2. Critically, the patent also discloses an intermediate adapter 19 whose shank 19c fits the steep spindle bore 2 and which has an internal bore 19i of "relatively slight taper per unit of length" receiving the arbor 20 shank 20c. The text expressly explains that because of the "relatively small taper" of shank 20c, "the engagement of the arbor 20 and adapter 10 is semi-permanent." The same rod 8, using its smaller threaded end 10, engages the arbor 20 directly when the adapter is used, versus the larger threaded end 9 when it is not.

• § 102 analysis vs. claim 1: Does not anticipate claim 1 — but this is the most substantively interesting of the four because it prefigures the dual-taper adaptor idea itself. Specifically it discloses:

  • element (a): a rotary spindle with a tapered socket;
  • element (b): a rod movable along the spindle axis;
  • a two-different-tapers arrangement: a steep outer taper (spindle/adapter) and a slender inner taper (adapter/small-arbor bore) — structurally the ancestor of claim element (e);
  • two rod-to-tool interfaces, one used with the adapter and one without — superficially analogous to elements (f)/(g).

  However, it is missing the two elements that give claim 1 its inventive character under the spring-force theory: there is no spring means, and no hydraulic jack. Tightening in Armitage is by manual wrench applied to hexagon portions 6b/8a (threaded sleeve 6 turning rod 8). There is therefore no "spring more compressed when the adaptor is not used / less compressed when it is" geometry (element g's relative-position limitation) and no equal-normal-force functional clause (h). Because § 102 requires every element in a single reference, no anticipation — Armitage is a § 103 candidate when combined with a spring/hydraulic drawbar reference (e.g., US 3,177,775).

• OCR caution: The reference PDF's running footer renders the patent number as "1,704,361" in one place; that is an OCR/typo artifact of 1,794,361, not a second document. I have not "corrected" it in the citation, only flagged it.

3. US 3,118,345 — Bullard, "Tool spindle drawbar"

• Full citation: US 3,118,345, "Tool spindle drawbar," granted 1964-01-21 (filed before that; filing date not captured in my retrieval), USPC 279/4.
• Description: A power-operated tool spindle drawbar — by title and class (279/4 = chucks/sockets with fluid-pressure actuator) this is the reference most directly on the hydraulic/spring drawbar actuation environment of claim 1. The Bullard company (Edward P. Bullard / The Bullard Company) was a major machine-tool concern; the family includes large control patents such as US 2,384,809 in the same era.
• § 102 analysis vs. claim 1: Almost certainly does not anticipate claim 1. Even granting it discloses elements (a)–(d) (spindle + drawbar + spring bias + hydraulic/power actuation to release), it is a drawbar reference and does not disclose the removable dual-taper adaptor with "a coaxial frusto-conical socket of solid angle substantially smaller than that of the spindle socket" (element e), the two distinct interconnecting means (f)/(g), or the equal-normal-force functional clause (h). It is § 102(a)/(b) art relative to the 1964-12-04 priority date.
• Confidence note: I was unable to retrieve the full text or claims of US 3,118,345 before the tool-step limit. The above is a classification/title-based assessment only and is the lowest-confidence item in this report. If precision matters, the claim text of US 3,118,345 should be pulled directly.

4. US 3,177,775 — Alisauskis, "Automatic draw bar mechanism for machine tool spindle"

• Full citation: US 3,177,775 A, Edward M. Alisauskis, "Automatic draw bar mechanism for machine tool spindle," filed 1963-03-28, granted 1965-04-13, assignee Scully Anthony Corp.

• Description (from the granted text): A rotatable machine-tool spindle 26 with a tapered socket 28 and a cylindrical bore section 30 ending in a frusto-conical shoulder 32. A split collet 36 with flexible fingers 38 grips a knob 14 on the tool holder 10; a draw bar 50 threaded into the collet moves it axially. The stated objects are explicit: "spring means for actuating an associated collet to closed position and non-rotatable piston and cylinder means for actuating the collet to open position." There is also ejecting means (cap screw 52 with pin 53) to aid release of a tool seated in the tapered socket.

• § 102 analysis vs. claim 1: Does not anticipate claim 1 — but it is the closest prior art on the actuation half of the claim. Mapping:

  • (a) rotary spindle with tapered socket — Yes (spindle 26, socket 28).
  • (b) rod movable along spindle axis — Yes (draw bar 50).
  • (c) spring means biasing the rod toward tightening — Yes, functionally (spring-actuated collet to closed position; spring is the tightening element, as in claim 1).
  • (d) hydraulic/piston means driving the rod toward the socket against the spring — Yes functionally (non-rotatable piston-and-cylinder means actuating the collet to open/release position, working against the spring). Note the Alisauskis actuator is described as piston-and-cylinder (fluid-pressure) means; claim 1 says "hydraulic jack."
  • (e) removable dual-taper adaptor with a smaller-solid-angle socket — No. Alisauskis uses a single tapered spindle socket; there is no adaptor, no second taper of smaller solid angle.
  • (f)/(g) first and second interconnecting means with the relative spring-compression geometry — No.
  • (h) equal-normal-force functional clause — No.

  Status as art: Although US 3,177,775 issued 1965-04-13 (after the 1964-12-04 Swiss priority date), its filing date of 1963-03-28 predates the priority date, which makes it available as prior art under the pre-AIA § 102(e) (US patent granted on an application filed before the applicant's date of invention/priority). This is worth flagging as an evidentiary point in any § 103 combination.

Bottom line on § 102

None of the four cited references anticipates the single claim of US 3,424,055. Anticipation requires that a single reference disclose every element, arranged as in the claim. The four references split cleanly along the two halves of the invention:

• US 3,177,775 (and, to a lesser extent, US 3,118,345) supply the spring-biased drawbar + powered release actuator half — claim elements (a)–(d).
• US 1,794,361 supplies the two-taper / removable-adaptor half, including an adapter with a slender inner bore — a structural ancestor of element (e), plus the notion of alternating rod-to-tool interfaces (f)/(g).

Each is missing the other's contribution, and no one of them discloses the spring-compression-vs-taper relationship (element g's relative position/compression limitation) or the equal-normal-force functional clause (element h), which are the point of novelty the specification itself identifies (see the "characterized by the fact that…" passage, and the A.S.A.-29.17%/Morse-5% self-locking rationale).

Implied § 103 posture (offered because it is the operative question)

Because there is no anticipation, the real exposure is obviousness. The primary candidate combination an examiner or challenger would assemble is US 1,794,361 (dual-taper adaptor) + US 3,177,775 (spring drawbar with powered release), optionally with US 3,118,345 for the hydraulic-jack teaching, to render claim 1 obvious. The pivot point a validity defense would rest on is the counterintuitive "lower drawbar force for the self-locking cone" geometry — i.e., the recognition that the slender Morse-type taper should be given less spring force (because it is self-locking and needs little drawbar load but much release effort), achieved automatically by the longer extension b > a — a relationship none of the four references states or suggests. (Both a and b are described in the specification; see the "length b of the extension 39 being greater than the length a" passage.)

Explicit flags and caveats

• Coverage gap / confidence: I fully read the texts of US 1,794,361 and US 3,177,775. I did not obtain the full claims of US 1,442,659 and US 3,118,345; conclusions on those two rest on title, date, assignee and classification only and are lower-confidence.
• Duplicate listing, not a duplicate patent: The OCR reference list on the US 3,424,055 record shows US 1,794,361 entered twice ("…Armitage et al 90-l.1" and "…Armitage et al. 90-l1.1"). There is only one such patent; this is an OCR/transcription duplication. Per the strict-literal rule I have not silently merged or renumbered anything — I flag it rather than correct it.
• "Solid angle" wording: As noted in the earlier sections, the specification's "29.17%" and "5%" are taper ratios, not angles in degrees/steradians. I have carried that terminology verbatim into the claim-element mapping and not reinterpreted it.
• Two assignee strings / chain of title: unchanged from the earlier sections — the Google Patents record shows both "GENEVOISE INSTR PHYSIQUE" and "GENEVOISE D'INSTRUMENTS DE PHYSIQUE SOC," read as name variants of one Swiss entity but not independently verified.
• Date discrepancy (flagged per your cross-reference instruction): the system clock for this analysis reads 2026-09-30, whereas the task header you supplied states April 26, 2026. Nothing in this § 102 analysis turns on the difference (the patent expired 1986-01-28 and all four references are long expired/public domain), but I am flagging it rather than silently reconciling it.
• All four cited references remain relevant today only as prior art in the tool-holder field (notably the Harold D. Cook shrink-fit family that cites US 3,424,055), not as enforceable rights.

I'll ground this analysis by pulling the four cited prior-art references and checking a few secondary sources on taper-adaptor practice.

Now let me pin down the Bullard drawbar reference and the Groene spindle reference, plus the state of taper-adaptor practice.

Obviousness Analysis — US 3,424,055 under 35 U.S.C. § 103

Scope note: This builds on the previously generated summary, claim mapping, and litigation/status sections. I do not repeat them. Two housekeeping flags first:

• Date inconsistency in the inputs. The system context states "Today's date: 2026-09-30"; the task prompt states "Current Date: April 26, 2026." I have not adjusted either. Nothing in the §103 analysis below turns on the date, but the record should note the discrepancy.
• Tool-step limit. Two of my four follow-up searches were cut off by the step limit: (a) the full text of US 1,442,659 (Groene), and (b) a targeted search for pre-1965 taper-reducing-sleeve art. I flag where that affects my confidence below rather than papering over it.

1. Governing legal framework

The application was filed 1965-11-12, so pre-AIA §103 governs, with the Graham v. John Deere factors (scope/content of prior art; differences; level of ordinary skill; secondary considerations). KSR Int'l v. Teleflex (2007) supplies the controlling articulation of the "motivation to combine" inquiry and applies to pre-AIA law as well.

Because the patent expired 1986-01-28, this analysis is retrospective — its live use today is defensive (validity of later claims) and as prior art, not as an assertion.

Prior-art status of the four cited references (critical, because it is not uniform)

All four were cited of record and considered by Examiner Vlachos. Any obviousness theory must therefore explain why the examiner's allowance was wrong, not merely re-cite the art.

2. Element mapping of the sole claim

Claim 1 is independent and means-plus-function in part ("spring means," "first means for interconnecting," "second means for interconnecting"), so under pre-AIA §112 ¶6 it covers the disclosed structures (spring 9; couplings 10/36) and equivalents.

Identifier-collision warning (important, and easy to botch): Bullard's "adapter 32" / "adapter screw 26" and Alisauskis's "adapter 18" are drawbar-coupling adapters, not taper-reducing sleeves. Do not treat those disclosures as teaching Rollat's adaptor 14. The four cited references do not, on the record I verified, disclose a taper-reducing sleeve at all. Any §103 theory therefore has to reach outside the four references for that element — and that is exactly where the theory is weakest.

3. The combinations, and why a PHOSITA would have made them

Combination A (strongest): Alisauskis '775 + Bullard '345 + Armitage '361 + a taper-reducing sleeve

Motivation, drawn from the references themselves and from the patent's own admissions:

1. Alisauskis supplies the exact architecture of claim 1 — spring closes the grip, hydraulic piston opens it, drawbar axially movable in a spindle with a tapered socket. That is not a hint; it is the claim's operating principle minus the adapter.
2. The problem statement is the applicant's own. The specification concedes: "Each of both said types of cones has its advantages and its drawbacks so that it[s] useful for the user to have both types of cones on the same spindle," and it spells out the trade-off (Morse ≈5% self-locking → low tightening force needed, high release force; A.S.A. ≈29.17% → the reverse). Under KSR, a problem identified in the specification coupled with known elements in the field is the paradigm of obviousness.
3. Armitage '361 supplies the taper-selection knowledge — it explains at length that the steep 3.5-in-12 taper was chosen "primarily for the purpose of preventing sticking or binding of the tool when the tool is to be removed," while warning that "too steep a taper is not desirable for accurate alignment." A PHOSITA reading Armitage learns precisely the property Rollat exploits.
4. Bullard supplies a spring-loaded drawbar with a hydraulic actuator and a bayonet coupling to a tool shank whose axial engagement is set by an adjustable adapter screw and lock nut. Once a PHOSITA accepts that one spindle should take two different taper systems, adapting the drawbar-to-tool coupling for the two seating depths is a length selection — the smallest kind of mechanical design choice.

Why the result is not patentable weight: the final clause recites a result. Hooke's law — a spring exerts more force when more compressed — is elementary, and the geometry (deeper seating → rod stops further rearward → less compression) follows inevitably. A claimed result that flows inevitably from the claimed structure does not distinguish over the prior art. Even if it were not deemed inherent, the §103 answer is the same: choosing the extension length is optimization of a result-effective variable, and "[t]he law of diminishing returns" reasoning applies. See In re Boesch / In re Aller line of authority referenced in MPEP 2144.02–.03.

Combination B: Bullard '345 as primary + Armitage '361 + known taper sleeves

Same result via a different primary. Bullard is a single-spindle drawbar reference disclosing tapered socket, drawbar, spring, hydraulic cylinder, and a bayonet coupling — arguably the closest single-reference teaching of the "means for interconnecting" elements. Combine with Armitage for taper-property knowledge and with the notional sleeve. This combination is slightly weaker because Bullard uses hydraulics for clamping as well as release (the spring is a bias), so the "normal force substantially the same" result is less directly inherited.

Combination C: Groene '659 as general background

Only bibliographic data was confirmed (via third-party citation lists and the datamp.org LeBlond patent index); I did not open the Groene specification and therefore will not assert what it discloses. It appears among the "References Cited" of '055 and in the LeBlond corporate portfolio, so treat it as a milling-spindle art reference only. Do not build a combination on it without reading it.

4. Counterarguments a patent owner would raise, and the response

5. Conclusion

On the record as it exists, US 3,424,055 would likely be held non-obvious on the four cited references standing alone — but only because none of them discloses the taper-reducing adaptor, which is the structural core of the claim. The remaining elements (drawbar, spring-clamping/hydraulic-releasing, tapered socket, coupling means) are cumulatively and squarely disclosed, most directly by Alisauskis '775 in combination with Bullard '345 and Armitage '361.

If a pre-1964 reference showing a taper-reducing sleeve or bushing is added to the four (or if sleeve adaptors are established as within the ordinary skill and knowledge of a 1964 machine-tool designer), the claim falls to §103. In that event the motivation is supplied by the applicant's own statement of the problem, the taper-property teachings of Armitage, and the elementary, predictable Hooke's-law consequence of a deeper-seated shank on a spring-biased drawbar.

Confidence — high on the Bullard, Armitage, and Alisauskis disclosures (quoted above from the grant documents). Low on the taper-sleeve point (search truncated) and on Groene's disclosure (not opened). I have not auto-corrected any identifier; "3424055," "3,424,055," "3,118,345," "3,177,775," "1,442,659," and "1,794,361" are used as printed.