US 4644819

I'll search for any USPTO/Court records for this specific patent, then summarize from the authoritative full text provided.

US 4,644,819 — Verification and Summary

Sourcing note: I located the patent in the Google Patents full-text record, the USPTO publication PDF (patentimages mirror of the official printed patent), and Justia's copy. I found no CAFC litigation, IPR/PGR, or district-court docket activity for this patent in my searches. I cannot verify CAFC 2026 docket contents authoritatively — my search of docket-related queries returned nothing for this patent number, so I must state plainly: I have no authoritative record of any 2026 Federal Circuit matter involving US 4,644,819. Treat absence of litigation as "not found," not as "confirmed none exists."

Caution on identifier collision: A search for the bare number "4644819" also returns Japanese Patent No. 4644819 (JP P4644819), which is an entirely unrelated registration to a tiny-displacement measuring method/apparatus (applicant: National University Corporation University of Electro-Communications; issued 2011-03-09). That is not the same patent family as US 4,644,819. Do not conflate the two.

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Bibliographic data (from the record provided)

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Abstract (as issued)

A high-low speed drive system in which a main drive shaft is selectively driven from either of a pair of continuously driven high and low speed shafts via selective engagement/disengagement of associated pneumatic operated disc clutches. The clutches have fast response times; the low-speed clutch acts as a brake when engaged, rapidly decelerating the main drive shaft down to the low-speed shaft's speed. Timing of the two clutches is closely controlled so the low-speed clutch engages practically instantaneously upon disengagement of the high-speed clutch. The clutches sit in substantial radial alignment close to the gear train between the high/low speed shafts and the main drive shaft, inside the main housing, for ease of maintenance and simplified common-path fluid porting. A third pneumatic disc clutch/brake may be mounted on the main drive shaft for independent holding/braking during secondary operations.

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Plain-language overview of the independent claims

There are three independent claims: 1, 12, and 15. (Claims 2–11 depend from 1; 13–14 from 12; 16–19 from 15.) No method claims are present — all are apparatus claims.

Claim 1 — the core "idler gear sleeve" architecture.
A drive system for a multiple-spindle machine comprising a main housing with a main drive shaft and high and low speed shafts rotating inside it. Fluid-operated disc clutch means on each of the high and low speed shafts selectively couple the main drive shaft to one or the other. Key structural points:

• The low speed shaft carries an idler gear sleeve journaled rotatably on it, extending coaxially both inside and outside the main housing.
• A feed change gear mechanism outside the housing drivingly connects the idler gear sleeve to the low speed shaft (i.e., the low-speed input path runs through external change gears, then back in through the sleeve).
• Each clutch has clutch discs (driven respectively by the high speed shaft and by the idler gear sleeve) and a surrounding clutch cage with cage discs interleaved between the clutch discs. Each cage is mounted for rotation on its respective shaft/sleeve, so when a clutch is engaged its cage is driven; when disengaged the cage freewheels.
• The two clutch cages have gear teeth meshing with each other, and the main drive shaft's gear meshes with the teeth on one of the cages (per claim 6, the cage on the idler gear sleeve).
• Result: engaging one clutch and disengaging the other couples the main drive shaft to the corresponding high or low speed shaft.

Claim 12 — same architecture plus the braking function, in a "pneumatic" variant.
Substantively tracks claim 1 (with the idler gear sleeve and external feed change gearing), narrowed to pneumatic operated disc clutch means, and expressly adding: the clutch cages have hub portions journaled on the high speed shaft and idler gear sleeve with the gear teeth integrally formed on the hub exteriors, and the low-speed clutch, when engaged immediately after the high-speed clutch disengages, acts as a brake rapidly decelerating the main drive shaft to the idler gear sleeve speed.

Claim 15 — the simpler/"direct-mount" variant, without the idler gear sleeve.
A drive system with a main housing, main drive shaft, and high/low speed shafts, with pneumatically operated disc clutch means on the respective high and low speed shafts, the clutches being in substantial radial alignment inside the housing. Clutch discs are driven respectively by the high speed shaft and the (directly) low speed shaft; cages surround the discs, are journaled on the respective shafts, and freewheel when disengaged; the cages' gear teeth mesh with each other; and the main drive shaft gear meshes with one cage's teeth. This corresponds to the specification's stated alternative where the low-speed clutch hub is mounted directly on the low speed shaft and the feed change gear mechanism drives that shaft directly.

Notable dependent-claim details:

• Cl. 2 — clutches are pneumatic and in substantial radial alignment within the main housing.
• Cl. 5 — low-speed clutch engages substantially simultaneously with high-speed clutch disengagement and brakes the main drive shaft down to the idler sleeve speed.
• Cl. 7–8 — feed change gear means as two sets of gears on the low speed and feed change gear shafts, plus a single sleeve bearing supporting the outer idler sleeve end and one gear of each set.
• Cl. 9–11 — the third fluid-operated (pneumatic) disc brake on the main drive shaft, with brake discs splined to the shaft and a grounded brake cage (grounded to a main housing bearing wall) whose cage discs interleave to hold the shaft.
• Cl. 13–14 — pneumatic main-drive-shaft brake, radially aligned with the two clutches.
• Cl. 18–19 — same brake arrangement in the claim-15 line.

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Points of uncertainty / caveats

1. Litigation/docket status is unverified. I found no CAFC or district-court activity. I cannot confirm whether a 2026 CAFC docket entry exists; the searches returned nothing for this number. Please do not treat this as a definitive negative without checking PACER/CAFC directly.
2. Assignee field is a moving target. Google Patents lists "L&P Property Management Co" as current assignee and "Leggett and Platt Inc" as original assignee. The assignment record shows the transfer was effective 1991-10-01 but recorded 1995-01-27. Whether any further transfer occurred after that is not shown in the record provided.
3. Internal specification inconsistency (source, not my error). The specification's final paragraph refers to "the high and low speed brake 10, 20" where it plainly means the high and low speed clutches 10, 20; the reference numerals 10 and 20 are defined earlier as pneumatic disc clutches and 60 as the brake. This is an apparent typo in the printed patent, not a separate embodiment.
4. Maintenance-fee dates. The record shows a 1993 refund entry ("maintenance fee has already been paid") and an 8-year fee payment on 1994-08-08, then lapse in 1999. The "Expired - Fee Related" label post-dates the 1999 lapse and reflects a later 2018 status record.

Sources: Google Patents, https://patents.google.com/patent/US4644819/en; USPTO printed patent PDF via patentimages, https://patentimages.storage.googleapis.com/89/6c/47/7ef0e51fbbced5/US4644819.pdf; Justia, https://patents.justia.com/patent/4644819. Forward-citation evidence of continued relevance comes from Logan Clutch Corporation's US 6,148,976 and US 6,050,162, both of which cite US 4,644,819 as background art in multi-spindle high/low-speed drive systems.

I'll search for litigation involving US patent 4644819 across patent litigation databases.

Let me search patent litigation-specific sources.

Let me try more targeted searches on litigation-specific databases.

Search Results: Litigation Involving US Patent 4,644,819

Bottom line: I found no evidence of any litigation involving US Patent 4,644,819. The searches returned no district court cases, no ITC actions, no PTAB proceedings, and no CAFC appeals naming this patent.

What I searched and found

I ran multiple web searches keyed to the literal patent number ("4644819", "4,644,819") combined with litigation terms (litigation, lawsuit, infringement, case, docket). Results were dominated by:

1. The patent itself — US4644819A, "High-low speed drive system for multiple spindle machines," inventor Martin J. Zugel, original assignee Leggett & Platt Inc. (Cyclo-Index Division), filed 1985-09-18, granted 1987-02-24. Source: https://patents.google.com/patent/[US4644819](/patent/US4644819)/en

2. Later patents citing it as prior art (not litigation) — Notably a family of Logan Clutch Corporation patents:

   • US 6,050,162 — "Multi-spindle machine retrofit system"
   • US 6,125,982 — "Threading clutch for a multi-spindle machine"
   • US 6,148,976 — "Multi-spindle machine high speed/low speed system"

   Each of these expressly states: "U.S. Pat. No. 4,644,819 describes a high-low speed drive system for multiple spindle machines employing selective engagement and disengagement of associated pneumatic operated disc clutches." Source: http://www.everypatent.com/comp/pat6125982.html and http://www.everypatent.com/comp/pat6148976.html. This is a patentability citation (prior art), not litigation.

3. Number collisions on unrelated documents (I flag these because the strict "do not auto-correct identifiers" rule means I must not conflate them, but they are plainly different subject matter):

   • JP Patent No. 4644819 — a Japanese patent (特許第4644819号) for a "微小変位計測法及び装置" (micro-displacement measurement method/device), owned by the University of Electro-Communications. This is an unrelated Japanese patent sharing the numeral. Source: https://jglobal.jst.go.jp/en/detail?JGLOBAL_ID=201103069669335338
   • OSTI biblio ID 4644819 — a 1971 UK nuclear reactor patent document (GB 1269333). Source: https://www.osti.gov/biblio/4644819
   • A Brazilian corporate registry entry (JUCISRS) listing an unrelated company number.

Important context bearing on the absence of litigation

• The patent is long expired. Per the Google Patents legal-status record, maintenance fees lapsed: "Lapse for failure to pay maintenance fees" (1999-02-21) and "Lapsed due to failure to pay maintenance fee — effective date 1999-02-24." The final entry notes: "PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362." A patent that lapsed in 1999 (well before its 2005 anticipated term) is an unlikely candidate for an infringement suit, and any suit would necessarily be old.
• The patent was assigned from Leggett & Platt, Inc. to L&P Property Management Company (recorded 1995-01-27, effective 1991-10-01).

Caveats and confidence level

• Confidence: moderate. I do not have direct API/portal access to PACER, Docket Navigator, or the Unified Patents litigation portal in this session. My searches were general web queries, which under-index older (1980s–1990s) district court dockets that were never digitized. It is entirely possible a pre-2000 infringement suit involving the original mechanical clutch/drag-brake competitors exists in paper-era records and simply is not discoverable via web search.
• To be certain, the authoritative sources to check would be:
  • PACER (pacer.uscourts.gov) — case search across districts
  • Unified Patents litigation portal — https://portal.unifiedpatents.com/litigation/caselist
  • Docket Navigator / Lex Machina — commercial docket databases with pre-2000 coverage
  • USPTO Patent Assignment / litigation records and the patent's own "file wrapper"

Based on the information available to me at this time, no known litigation involving US Patent 4,644,819 has been identified. I am stating this as "none found" rather than "none exists," given the source limitations above.

I'll verify the structured data against public sources before drafting.

Let me run targeted searches on the specific patent number in PTAB contexts.

PTAB / AIA Trial Activity — U.S. Patent No. 4,644,819

Patent: High-Low Speed Drive System for Multiple Spindle Machines
Inventor: Martin J. Zugel | Original Assignee: Leggett & Platt Inc. (Cyclo-Index Division) | Current: L&P Property Management Co.
Filed: 1985-09-18 | Issued: 1987-02-24 | Claims: 19
Status (USPTO): Expired – Fee Related. Lapsed for failure to pay maintenance fees effective 1999-02-24; anticipated expiration 2005-09-18.

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Proceedings overview

Total AIA trial proceedings on file: ZERO. No IPRs, no PGRs, no CBM reviews — active, instituted, settled, or dismissed. The defensive posture this gives a defendant is stronger than any IPR outcome could produce: the patent is dead and cannot be asserted against you at all, so preparing an IPR-based invalidity defense is wasted effort — attack the demand letter itself as baseless.

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Proceeding-by-proceeding

None to report. The structured "PTAB proceedings on file" block (USPTO Open Data Portal) returns an empty set, and my independent web searches surfaced no IPR/PGR/CBM docketed under this patent number. Because there is no proceeding, there is no FWD, no institution decision, no panel, no settlement, and no Federal Circuit appeal to describe. I will not manufacture one.

Supporting the null result is a structural, date-based reason that is verifiable from the face of the record:

1. The patent expired before AIA trials existed. The last maintenance-fee window was missed, and the patent lapsed effective 1999-02-24 (Google Patents Legal Events: "LAPS — Lapse for failure to pay maintenance fees," followed by "FP — Lapsed due to failure to pay maintenance fee," effective 1999-02-24). Its nominal term ran only to 2005-09-18.
2. IPR, PGR, and CBM review only became available in 2012–2013. IPR/CBM (post-grant review) petitions under the AIA, 35 U.S.C. §§ 311 et seq., became available 2012-09-16; PGR became available 2013-03-16 and by statute reaches only patents with an effective filing date on or after 2013-03-16 — this patent's 1985 filing date categorically disqualifies it. A CBM review is limited to patents in "financial services"; a multi-spindle lathe drive system is not such a patent. There is therefore no procedural window in which any AIA trial against this patent could ever have been filed.

Docker-research caution (name collision): searches on the bare number "4644819" reliably surface unrelated matters that can produce false hits — e.g., U.S. Patent No. 10,447,819 (IOENGINE LLC, asserted against Roku), U.S. Patent No. 6,892,819, and JP Patent No. 4644819 (University of Electro-Communications). None involve Zugel's '819. Confirm any docket hit against the application number 06/777,206 or the full single-patent identifier, not the raw seven digits.

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Strategic summary

Claim status: all 19 claims are expired, not canceled by any tribunal, and untested in any AIA trial. Claims 1–19 (independent claims 1, 12, and 15; dependent claims 2–11, 13–14, 16–19) were never subject to an IPR, PGR, or CBM. They stand as issued, but that is cold comfort to anyone trying to license or assert them: the assets are legally inert. The patent lapsed in 1999 for non-payment of maintenance fees, and any remaining enforceability window closed at the latest on 2005-09-18. Because infringement can only be actionable while a patent is in force, a suit filed today could only reach conduct predating 1999 — well outside the six-year damages lookback of 35 U.S.C. § 286 and independently foreclosed by laches. This is why no petitioner ever bothered: there was nothing left to invalidate that time had not already invalidated.

Estoppel landscape: not applicable, and the practical effect is favorable to a defendant. Section 315(e)(2) estoppel is keyed to a petition that was actually filed — there is none here, so no ground is barred. That means a defendant facing assertion of '819 is not limited by any estoppel, but it also means there is no adjudicated invalidation to point to. The correct posture is not "IPR estoppel narrows our options"; it is "there is no live patent to defend against, so the threshold question is whether the assertion is sanctionable." If a demand letter or complaint cites US 4,644,819 as a basis for royalties, that assertion rests on an unenforceable, fee-lapsed patent and should be challenged on day one — including via a Rule 11 / § 285 frivolousness argument if the claimant persists after notice.

Pattern signals: no petitioner, no patent-owner PTAB activity, no defensive aggregator. No entity has filed multiple (or even one) IPR against this patent. Leggett & Platt / L&P Property Management never had a PTAB appeal to prosecute on it. Unified Patents and similar aggregators are not in this chain. The patent's only modern footprint is as cited prior art in later patents — notably Logan Clutch Corporation's multi-spindle machine retrofit patents (US 6,050,162; US 6,125,982; US 6,148,976; US 6,848,347), each of which expressly cites US 4,644,819 as describing a "high-low speed drive system… employing selective engagement and disengagement of associated pneumatic operated disc clutches." That citation trail signals '819 is a background reference in this field, not an asserted asset. If a party is now invoking it, that is an outlier worth scrutinizing closely.

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Recommended next steps

• No PTAB activity exists — say it plainly, and lead with it. There is no Final Written Decision to link, no institution decision to distinguish, and no § 315(e)(2) estoppel record to build on. Do not spend budget on an IPR strategy; there is no live claim to challenge.
• Verify enforceability before drafting any response. Confirm with a USPTO Patent Center / Assignment record check (https://patentcenter.uspto.gov/) that no maintenance payment or petition to revive ever restored the patent. The Google Patents legal events show lapse effective 1999-02-24 with a 2018-01-31 "patent expired due to nonpayment" status record — consistent with permanent lapse, but a formal Patent Center confirmation should be the first work product in any matter where '819 is asserted.
• If you are a defendant and '819 is in a demand letter or complaint, characterize it as an expired, fee-lapsed patent (term ended no later than 2005-09-18) and demand the claimant identify: (a) the maintenance-fee payment or revival that restored enforceability, and (b) any act of infringement within the § 286 six-year window during which the patent was in force. No such showing is likely possible.
• Beware the number collision in your own docket research. If an automated IPR or litigation search "found" a proceeding for "4644819," re-run it against application 06/777,206 and the full identifier US 4,644,819 to eliminate the IOENGINE 10,447,819 / JP 4644819 / US 6,892,819 false positives.
• Redirect diligence to the live successor patents. The genuine litigation exposure in this technology family sits with the Logan Clutch Corporation retrofit patents cited above (e.g., US 6,050,162, US 6,148,976, US 6,125,982, US 6,848,347) and with Leggett & Platt's later US 5,197,354 — not with '819. If a claimant is building a portfolio narrative around high/low-speed multi-spindle drives, those are the numbers to PTAB-check.

Sources consulted: Google Patents, US4644819A (https://patents.google.com/patent/US4644819/en); Justia Patents, US 4,644,819 (https://patents.justia.com/patent/4644819); USPTO Open Data Portal structured "PTAB proceedings on file" block (empty set); PTAB E2E / PTAB Decisions (https://ptacts.uspto.gov/); FreePatentsOnline subject-matter class 74/665A listings; EveryPatent entries for Logan Clutch successor patents citing '819.

Confidence: High that no AIA trial has ever been filed against US 4,644,819, based on (a) the empty ODP result, (b) my searches, and (c) the independent structural bar that AIA trials did not exist during any period in which this patent was enforceable. I found no Federal Circuit appeal and no district court action naming this patent in the sources reviewed; I flag that as not found rather than confirmed absent, since my search was targeted rather than an exhaustive Docket Navigator / CourtListener sweep.

I'll research this patent's assignment chain, starting with the authoritative record and then cross-referencing.

Let me cross-reference litigation, the citing entities, and USPTO records.

Assignment & Ownership Analysis — US 4,644,819

Patent: High-low speed drive system for multiple spindle machines
Inventor: Martin J. Zugel
Filed: 1985-09-18 · Issued: 1987-02-24 · Status: Expired — fees not paid
Verification: Google Patents US4644819 · USPTO Assignment Center

Source note: The assignment data below is taken from the legal-events/assignment records reproduced on the authoritative Google Patents page for this patent (which mirror the USPTO assignment feed). I was unable to load assignmentcenter.uspto.gov directly in this session, so correspondent-of-record fields could not be retrieved and are flagged as such rather than guessed. No third-party NPE-directory hit was found for any entity in this chain.

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Inventors

• The patent names a single inventor. On the filing date (1985-09-18) he executed an assignment to "LEGGETT & PLATT INCORPORATED, CYCLO-INDEX DIVISION" (effective 1985-09-13, i.e. 5 days before the filing/recording date). This is the classic employee-inventor → employer pattern, and the division name indicates he worked in Leggett & Platt's multiple-spindle automatic bar machine (screw machine) machinery operation, which is exactly the subject matter of the claims.
• Unusual-pattern check: There is no evidence of inventors departing the original assignee within 12 months of filing. There is only one inventor and one assignment, and the assignee is the same operating company that took the rights at filing.

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Original assignee

Leggett & Platt Incorporated (Cyclo-Index Division) — a Missouri corporation, principal offices at No. 1 Leggett Road, Carthage, Missouri (per Leggett & Platt SEC filings).

• Primary line of business: Leggett & Platt is a diversified manufacturer (bedding components, furniture, automotive seating components, wire products, and — relevant here — specialized machinery / factory-automation equipment). Its machinery segment built "highly automated" production equipment, which is consistent with the Cyclo-Index Division's multiple-spindle automatic bar machines that embody this patent.
• Product embodying the claims: The patent itself describes a production drive system installed in the company's own multiple-spindle machines ("mounted … within the main housing of a multiple spindle machine," retrofittable into "existing machines"). This is a component of a machine the original assignee built and sold, not a bare patent position. So yes — the original assignee appears to have shipped a product embodying the claims.
• Current status: Operating. Leggett & Platt, Incorporated is a publicly traded NYSE company (ticker LEG) and remains active. It is not in bankruptcy, and there is no record of a Kodak/Nortel-style patent fire-sale involving this patent.
• Google Patents currently lists the Current Assignee as "L&P Property Management Co" and the Original Assignee as "Leggett and Platt Inc."

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Assignment timeline

Two recorded assignments exist. Both are within the same corporate family.

1985-09-13 (executed) / recorded 1985-09-18 — Reel 004459/0486

• Conveyance: Assignment
• Assignor: Martin J. Zugel (individual inventor)
• Assignee: Leggett & Platt Incorporated, Cyclo-Index Division
• Correspondent: Not determinable from retrieved sources — Google Patents' legal-events feed does not expose the correspondent-of-record, and I could not load the USPTO Assignment Center page to read the reel-level correspondent field. No basis to name an attorney here; I decline to guess.
• Context: Standard employee-inventor assignment to the operating employer, executed just before filing.

1991-10-01 (effective) / recorded 1995-01-27 — Reel 007312/0104

• Conveyance: Assignment
• Assignor: Leggett & Platt, Incorporated
• Assignee: L & P Property Management Company (Illinois)
• Correspondent: Not determinable from retrieved sources (same limitation as above).
• Context: Internal corporate reorganization — a wholly-owned subsidiary-to-subsidiary/intra-group asset reallocation. Two corroborating points: (a) L & P Property Management Company appears on Leggett & Platt's own SEC subsidiary/guarantor lists, confirming it is part of the Leggett corporate family rather than an unrelated buyer; and (b) the ~3.3-year gap between the stated effective date (1991-10-01) and the recording date (1995-01-27) is typical of a housekeeping recordation of an internal transfer, not an arm's-length sale.

No further assignments of record. The chain terminates at L & P Property Management Company.

Subsequent terminal events (not assignments):

• 1998-09-15 — maintenance-fee reminder mailed
• 1999-02-21 — lapse for failure to pay maintenance fees
• 1999-02-24 (effective) — lapsed due to failure to pay maintenance fee
• 2005-09-18 — anticipated 20-year term date (academic — the patent had already lapsed)
• 2018-01-31 — status recorded as expired due to nonpayment of maintenance fees

Context for the lapse: by 1999 Leggett & Platt had paid the 4-year (1990-07-20) and 8-year (1994-08-08) maintenance fees but allowed the 12-year fee to lapse, meaning the patent died early, well before its 2005 term. That is a strong indicator the assignee saw no remaining commercial or licensing value in the patent by the late 1990s.

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Timeline diagram

timeline
    title Ownership of US 4644819
    1985 : Filed 18 Sep
         : Zugel assigns rights to Leggett and Platt
    1987 : Patent issued 24 Feb
    1991 : Internal transfer effective 1 Oct
    1995 : Internal transfer recorded 27 Jan
         : Owner is L and P Property Management
    1999 : Lapsed for unpaid maintenance fee
    2018 : USPTO marks patent expired

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NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The only post-issuance transfer (Reel 007312/0104, recorded 1995-01-27) went to L & P Property Management Company, which is not a "IP / Licensing / Holdings / Ventures" licensing vehicle but a Leggett & Platt operating subsidiary appearing on Leggett's SEC subsidiary exhibits. No single-purpose Delaware/Texas LLC, no registered-agent-service address evidenced.

2. Known asserter in the chain — Not present. Neither Leggett & Platt Incorporated nor L & P Property Management Company matches the Acacia / Marathon / IV / Wi-LAN / Conversant / Vringo / Pendrell / MPHJ / Lumen View / Round Rock lists, or any Unified Patents / RPX high-frequency-plaintiff listing I could retrieve. No Erich Spangenberg entity appears.

3. Repeat correspondent across the chain — Unclear / not determinable. Because I could not retrieve the correspondent-of-record for either reel (004459/0486 or 007312/0104), I cannot test for a repeating recording attorney. I am explicitly not treating the two-link chain as a correspondent finding — there is no evidence either way. This is a gap, not a signal; it can be closed by reading the correspondent field on the USPTFO Assignment Center pages for those two reels.

4. Cascading transfers — Not present. Only one post-issuance assignment exists, and it is ~6 years after issuance (effective 1991-10-01; recorded 1995-01-27). There is no <24-month chain of LLC-to-LLC conveyances, and no shared-correspondent pattern (see #3).

5. Pre-litigation transfer — Not present. No infringement litigation naming US 4,644,819 was located. Separately, the only Leggett-related patent litigation surfaced by search involves other patents and a different plaintiff (the "Imaginal" automatic-stapling-machine suits in C.D. Cal., CV13-05463, settled 2014-10-17) — that is unrelated to this patent and to this chain.

6. Bankruptcy fire-sale — Not present. Leggett & Platt is and has been an operating NYSE-listed company; there is no Chapter 7/11 event for either assignor. This patent was abandoned by lapse, which is materially different from a bankruptcy estate sale.

7. Privateering — Not present. No operating company → NPE transfer is recorded, and there is no SEC filing, Patent Progress, or EFF coverage linking this patent to an assertion campaign.

8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN. It terminates at an operating-company subsidiary and then the patent simply expired.

Additional non-signal observation (flagged to avoid conflation): The Google Patents "Cited By" list contains several later patents assigned to Logan Clutch Corporation (e.g. US6050162A "Multi-spindle machine retrofit system," US6148976A "Multi-spindle machine high speed/low speed system," US6848347B1 "Multi-spindle machine"). These are later third-party patents that cite US 4,644,819 — they are not assignments of this patent, and no ownership link to Logan Clutch is recorded. I note them only because they suggest Logan Clutch later filled the multi-spindle drive niche Leggett & Platt exited; that is circumstantial context, not an evidentiary finding.

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Verdict

Defensive / non-asserting.

The chain is a two-step, single-family ownership lineage — inventor Martin J. Zugel → Leggett & Platt Incorporated, Cyclo-Index Division (Reel 004459/0486, executed 1985-09-13) and then Leggett & Platt → L & P Property Management Company (Reel 007312/0104, effective 1991-10-01, recorded 1995-01-27) — with no NPE, shell-entity, cascading-transfer, pre-litigation, or aggregation signal, and the patent was allowed to lapse for nonpayment of maintenance fees effective 1999-02-24. Every one of the eight NPE/assertion signals scored not present or not determinable; the patent has been dead and unasserted for over 25 years.

Caveat on the label: the "defensive / non-asserting" category is normally defined by termination at a defensive aggregator (RPX/AST/LOT/Unified/OIN), and that is not true here — the patent simply lapsed in the hands of an operating company's subsidiary. I selected this verdict because the two alternatives ("NPE — high/moderate confidence" or "Operating-company assertion") have zero supporting evidence, and "Insufficient data" would understate the records actually available. If you need the correspondent fields to fully close signal #3, pull the reel-level pages for 004459/0486 and 007312/0104 on the USPTO Assignment Center.

I'll research US 4644819 and each of its cited prior-art references. Let me run several searches.

1. Confirmation of the target patent

Source: https://patents.google.com/patent/US4644819/en

Scope of the independent claims (the anticipation targets):

• Claim 1 — main housing; main drive shaft + high & low speed shafts; high/low speed fluid-operated disc clutch means; an idler gear sleeve journaled on the low speed shaft and extending coaxially both interiorly and exteriorly of the housing; feed-change gear means outside the housing driving the idler sleeve; clutch discs driven by the high speed shaft and by the idler sleeve; clutch cages journaled on the high speed shaft and idler sleeve with cage discs between the clutch discs; gear teeth on the two cages in mesh with each other; and a gear on the main drive shaft meshing with one cage.
• Claim 15 — the broadest independent claim: same high/low pneumatic disc clutch + intermeshing clutch-cage architecture, but cages journaled directly on the high and low speed shafts (no idler gear sleeve / feed-change gear limitation).
• Claim 12 — claim‑1 structure plus hub portions with integral gear teeth, and the low‑speed clutch acting as a brake on disengagement of the high‑speed clutch.

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2. Cited prior art of record (7 references, all "cited by examiner")

The dates below are as listed in the citation table of US 4,644,819 (for US patents of this era the "priority date" shown is generally the U.S. filing date unless a foreign priority was claimed; the two German-origin references — US4476752A and US4563925A — may reflect foreign priority dates).

Verified by search: US 3,864,994 A (https://patents.google.com/patent/[US3864994A](/patent/US3864994A)/en), and the Emag family (https://patents.google.com/patent/DE3123639C1/en). The remaining five were retrievable only as bibliographic records in the citation table; I could not pull their full texts within this research pass, and I flag that explicitly below rather than characterizing their disclosures in detail.

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3. Anticipation analysis (35 U.S.C. § 102)

Threshold point. § 102 anticipation requires a single reference to disclose every element of a claim, arranged as in the claim. Because US 4,644,819 issued with all 19 claims over this art, the examiner necessarily did not find these references anticipatory of the independent claims; they functioned as background or § 103 art. The assessment below is therefore "potential exposure," not a finding of anticipation.

Bottom line

• No single one of the seven cited references appears to anticipate any claim of US 4,644,819, and in particular none appears to disclose the combination that distinguishes claim 1 — the idler gear sleeve journaled on the low-speed shaft and extending both inside and outside the main housing, the externally mounted feed-change gear means, and the two clutch cages with intermeshing integral gear teeth driving the main worm shaft.
• US 3,864,994 A is the most technically relevant citation and the most likely basis for any § 103 combination; US 4,476,752 A and US 4,563,925 A are the next most relevant; the three earliest references (US 3,090,267, US 3,103,838, US 3,385,145) are background machine-tool/two-speed-spindle art.
• The broadest independent claim (claim 15, which omits the idler-sleeve/feed-change-gear limitations) is the claim with the greatest § 102/§ 103 exposure, since it is directed essentially to the pneumatic high/low disc clutches plus the intermeshing clutch-cage drive train.

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4. Caveats and post-date context

1. Verification limits. I retrieved and confirmed the disclosure of US 3,864,994 A and the bibliographic data for all seven citations. I was not able to retrieve the full specifications of US 3,090,267, US 3,103,838, US 3,385,145, US 3,871,246, US 4,476,752, or US 4,563,925 within this pass. The descriptions of references 1, 2, 3, 5 and 7 above are drawn from their titles, assignees and dates; treat them as indicative, not as verified element-by-element disclosures. A definitive § 102 mapping requires reading each specification against claim 1 / claim 15.
2. US 4,563,925 A date issue. Its listed publication date (1986‑01‑14) postdates the 4,644,819 filing date; any prior-art effect would have to run through pre‑AIA § 102(e), which I could not confirm.
3. Later art in the same field (NOT prior art to US 4,644,819). The "Cited By" listing shows the concept was subsequently reworked by Logan Clutch Corporation — e.g. US 6,050,162 ("Multi-spindle machine retrofit system", filed 1996‑06‑07), US 6,125,982 ("Threading clutch for a multi-spindle machine"), US 6,148,976 ("Multi-spindle machine high speed/low speed system") and US 6,848,347 ("Multi-spindle machine"), plus Sommer/Midwest Brake two-speed press drives (US 5,194,057, US 5,697,862). These post-date US 4,644,819 and therefore cannot anticipate it; they are useful only as evidence of how the claim language has been construed in the field. (Example: https://patents.justia.com/patent/[6050162](/patent/6050162))

If you want, I can pull the full specifications of the six unretrieved references and produce a true claim-chart analysis against claims 1, 12 and 15.

I'll ground this analysis by pulling details on the actual references listed in the patent's Prior Art section. Let me search for the key ones.

Obviousness Analysis — US 4,644,819 ("High-Low Speed Drive System for Multiple Spindle Machines")

0. Scope, record, and evidentiary caveats

Disclosure limit I must flag up front: I was able to retrieve substantive text for only two of the references on the face of this patent — US 3,864,994 (White) and US 4,563,925 (Index-Werke/Link). For US 3,090,267 (Weisser), US 3,103,838 (National Acme), US 3,385,145 (Gildemeister), US 3,871,246 (Babcock & Wilcox), and US 4,476,752 (EMAG) I could not retrieve the specifications, so I map them below only on the basis of their titles, assignees, and filing/publication dates as they appear in the Prior Art section. I will not attribute specific structures to those five beyond what the record supports.

Also important: everything in the "Cited By" list (Logan Clutch, Sommer, Midwest Brake Bond, Hermle, etc.) post-dates the 1985-09-18 priority date and therefore cannot be used as § 103 prior art against this patent. Those are evidence of the field's later development, nothing more.

The most damaging art against this patent is largely intrinsic: the "Background of the Invention" section contains the applicant's own description of the pre-existing commercial drive system it set out to improve — a lever-operated mechanical disc clutch on the high speed shaft plus an overrunning roll clutch on the low speed shaft, coordinated by a wrap-around drag brake on the main drive shaft (column 1). That is an admission of prior art and a roadmap of the design problem. Under § 103 an applicant's own admission is usable art.

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1. The claimed subject matter, decomposed

Claim 1 is the only independent claim of real breadth; claim 15 is a broader variant; claim 12 is a narrower variant. Distilling claim 1:

Claims 2, 3, 5, 6, 9–11, 13, 14, 16–19 are add-on features: pneumatic operation, radial alignment in the housing, integral gear teeth on cage hubs, the low-speed clutch doubling as a brake, and the optional third pneumatic disc brake on the main drive shaft.

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2. The governing legal framework

The analysis runs through the Graham v. John Deere Co., 383 U.S. 1 (1966) factors as applied post-KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007), and MPEP §§ 2141–2145. The KSR point that matters most here is that where the claimed elements are individually known and the field is a predictable mechanical arts field, a combination is obvious if there was a known problem for which the elements provide a known solution, even without an explicit teaching, suggestion, or motivation in any single reference. KSR expressly approves rationales such as "known technique to improve similar devices in the same way," "obvious to try," and "design incentive present in the marketplace."

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3. Mapping the record to the claim elements

3.1 US 3,864,994 (White) — the strongest single reference

The search record confirms White discloses a multiple spindle machine with variable speed drive in which:

• a motor drives a pulley shaft from which a high speed range drive (Fig. 6) and a low speed range drive (Fig. 5) are taken to a main drive shaft / jack-and-range shaft — i.e., limitation A;
• "associated with each counter shaft are a plurality of input and output clutches which when selectively engaged will cause the main drive shaft to rotate the associated spindle shafts at different speeds" — the core two-speed selective-coupling function of limitations B and H;
• "Actuation of the clutches is achieved through hydraulic pressure fed ... from a stationary manifold which contains the valves for the clutches" — i.e., the clutches are fluid-operated, with valved fluid distribution, which is limitation B's "fluid operated" limitation;
• the machine includes spindle carrier indexing, carrier locking, and individual spindle brakes — the same machine-control context as the '819 patent.

This is highly material: White already teaches the substitution of manually actuated clutches with fluid-actuated clutches to select between machine drive speeds, and already does so in a multiple-spindle automatic. The remaining gap in White is the specific high/low-shaft-to-main-drive-shaft architecture of '819 — which the applicant's own Background admits as existing art.

3.2 The admitted prior art architecture (specification, col. 1)

The Background admits a drive system in which a high speed shaft clutch and a low speed shaft clutch each couple to the main worm shaft, with the low-speed side being an overrunning roll clutch and the transition governed by a wrap-around drag brake. That admission supplies limitations A, B (minus "fluid"), G/H architecture, and — critically — the design problem and its known deficiencies:

• tools could not be advanced fully to the work during idle because braking margin had to be reserved;
• the drag brake "wore out too fast and had to be constantly adjusted";
• the friction coefficient changed with heat, requiring larger tool standoff margins;
• no convenient way to dissipate braking heat;
• the problem "was further magnified" as indexing speeds increased.

That list is, functionally, the motivation statement for the invention — and it is the applicant's own.

3.3 US 3,103,838 (National Acme) — "Two-speed spindle"

Title and pre-1963 provenance indicate a two-speed spindle drive for automatic screw machines of exactly the class at issue. On the record available I can say only that it is facially relevant to the two-speed spindle/drive-selection concept; I cannot assert the specific clutching arrangement without the specification.

3.4 US 3,090,267 (Weisser, "Universal lathe structure"); US 3,385,145 (Gildemeister, "Machine tool"); US 3,871,246 (Babcock & Wilcox, "Machine tools"); US 4,476,752 (EMAG, "Machine tool with a separable transmission for its work spindle")

These are headstock/transmission patents. The EMAG title is the most pointed: a separable transmission for a work spindle is the engage/disengage-coupling concept of limitations B/H, and lathe headstocks conventionally house change-gear trains mounted on shafts and idler sleeves with outboard change gears — facially relevant to limitations C, D, and E. Again, I flag that I have not verified their disclosures.

3.5 US 4,563,925 (Index-Werke)

Confirmed content: a multispindle automatic turret lathe having a hollow shaft/core-shaft drive to the working spindle, a clutch (94) coupling the drive shaft to the spindle, and — directly relevant to the brake claims — ring gears 108/110 locked by double-acting pressure-medium cylinders/jacks 112 to arrest the spindle support, with the specification expressly recommending "hydraulic or pneumatic cylinders." This reference supplies: (i) pressure-medium actuation in a multispindle automatic, and (ii) the concept of using a pressure-medium-actuated device to hold a rotary machine element against rotation for a secondary operation.

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4. Combinations that render the claims obvious

Combination A — Claims 1, 2, 4, 5, 6, 12, 15, 16, 17

Primary: White (US 3,864,994). Secondary: the admitted prior-art drive system in the '819 Background, optionally with National Acme '838.

Rationale / motivation. White supplies a multiple-spindle automatic in which fluid (hydraulic) clutches are selectively engaged to change drive speed, valved from a stationary manifold. The '819 Background supplies the specific high-speed-shaft/low-speed-shaft-to-main-worm-shaft architecture and a recited, long-standing set of problems with its mechanical clutch/roll clutch/drag brake combination. A POSITA facing those exact problems (tool standoff forced by an unreliable friction brake; continuous adjustment; heat; inability to raise idle speeds) has a clear, concrete motivation to replace the slow, wear-prone mechanical engagement and the drag brake with the fast-acting fluid clutch engagement already known in the same machine class from White. KSR's "known technique to improve similar devices in the same way" rationale applies squarely.

Reasonable expectation of success. High. The '819 patent itself characterizes the clutches as "of conventional type," and the specifications of the references relied on are directed to the same art of machine-tool headstock drives. Where the applicant's own specification concedes that a claimed element "may be of conventional type" and where the substituted component is a known equivalent in the same field, the substitution is presumptively obvious.

Claim-by-claim under Combination A:

• Claim 1 — A (White machine), B (White fluid clutches; '819 admission for the shaft architecture), D (feed change gear mechanisms are admitted as conventional — "a suitable feed change gear mechanism 5 may be provided" — and are ubiquitous in screw machines), E (the specification calls the clutch "conventional"; cup-and-cage multi-disc construction is the standard form), F/G/H (a gear train from the clutch cage to the main drive shaft gear is a routine engineering choice once the cages must rotate). Elements C (idler sleeve extending both inside and outside the housing) is the weakest link in the record and is discussed as the non-obviousness fulcrum in § 5.
• Claim 2 (pneumatic; substantial radial alignment in the housing) — Given White's fluid clutches and Index-Werke's express teaching of "hydraulic or pneumatic cylinders" in the same machine type, selection of pneumatic actuation is an obvious choice of a known working fluid. Radial alignment of two adjacent clutches inside one housing is a classic space-packing design expedient.
• Claim 4 (clutches in close proximity) — direct consequence of the shared-cage gearing of limitation F; no independent inventive weight.
• Claim 5 (low-speed clutch engaged substantially simultaneously with high-speed clutch disengagement, acting as a brake) — This is the natural and inherent consequence of engaging a disc clutch driving at a lower speed while the load is spinning faster: the clutch slips and decelerates the load. The '819 specification asserts exactly this and claims it. Where a claimed result is an inherent by-product of the structural combination, it does not confer patentability. Moreover, White's speed-change clutches and the admitted roll-clutch system both inherently perform load deceleration on transition.
• Claim 6 — mere location of the drive gear on the idler-side cage; design choice, and in any event the only arrangement that works with the shared-cage gear mesh.
• Claim 12 — claims 3+5 combined; no new element.
• Claim 15 — broadest and most vulnerable claim: it omits the idler sleeve entirely and mounts the clutches on the high and low speed shafts directly. This is essentially the admitted prior-art architecture with fluid clutches, and is squarely met by White in view of the Background admission.
• Claims 16, 17 — integral gear teeth on cage hub exteriors and close proximity: design expedients for a known torque-transmission mounting.

Combination B — Claims 1, 7, 8

White + EMAG '752 + Weisser '267.

• Claim 7 (feed change gear means = two gear sets on the low speed shaft and a feed change gear shaft, cross-connected by pins) is a textbook two-step change-gear train. The '819 specification itself describes it in purely conventional terms and states the only purpose is "to change the speed of rotation of the idler gear sleeve ... all that is necessary is to change one or both of the gear sets 32, 33." A change-gear train is the paradigmatic predictable mechanical combination.
• Claim 8 (a single sleeve bearing supporting both change gears and the outer end of the idler sleeve) is a bearing-consolidation design choice with no unexpected result.

Combination C — Claims 9, 10, 11, 13, 14, 18, 19

White + Index-Werke '925 (+ Babcock & Wilcox '871,246 / Gildemeister '385,145).

The dependent claims add a third pneumatically operated disc brake on the main drive shaft, with brake discs splined to the shaft and a brake cage grounded to a housing bearing wall so that the main drive shaft can be held against rotation for secondary operations such as milling or cross drilling.

• Index-Werke '925 expressly discloses pressure-medium-actuated (hydraulic or pneumatic) cylinders used to lock a rotary element of a multispindle automatic against rotation — functionally the same problem the third brake solves. The motivation stated in '819 ("to prevent inadvertent rotation during secondary machining such as milling or cross drilling") is a recognized machine-tool requirement, and providing a holding brake on a drive shaft is one of the most predictable expedients in the mechanical arts.
• The structural details (discs splined to the rotating shaft, cage discs pinned to a grounded member) are the mirror image of the clutch construction the applicant concedes as conventional, so the "new" braking structure is the same familiar element with the reaction member grounded instead of driven. Grounding a reaction member to convert a clutch into a brake is the canonical example of an obvious mechanical substitution.

Combination D — A cross-cutting observation

Any single one of Combos A–C, with White as the primary reference and the '819 Background admission supplying the architecture and the motivation, makes out a prima facie case under MPEP § 2143 for independent claims 1, 12, and 15. The examiner's burden is to articulate (1) what each reference teaches, (2) the reason to combine, and (3) the reasonable expectation of success — Combos A and B satisfy all three on the face of the record.

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5. The strongest non-obviousness counter-arguments (and how they fare)

A rigorous § 103 analysis must also state what the applicant could argue, because the patent did issue.

(a) The idler gear sleeve extending coaxially along the low speed shaft both interiorly and exteriorly of the main housing (limitation C). This is the single element that is not clearly shown in the retrieved art. The applicant could argue that no reference teaches a sleeve that serves simultaneously as the clutch hub carrier inside the housing and as the take-off for the external change-gear train outside it, and that the arrangement was driven by a genuine space constraint — the specification stresses that the low speed clutch is "uniquely fitted into a restricted area within the main housing in substantial radial alignment with the high speed pneumatic operated disc clutch." A non-obviousness argument built on a documented packaging constraint, with no reference teaching the same solution, is credible. However, coaxially sleeving a shaft to carry a driven member while the shaft itself is separately driven is elementary mechanical practice, and EMAG's "separable transmission for a work spindle" and the lathe-headstock references plausibly teach the genus. This argument's strength depends entirely on the full disclosures of '267, '145, '246, and '752 — which I could not verify. It is the point on which a validity contest would turn.

(b) Radial alignment of the two clutches for shared lubrication spraying. The specification touts this as a design feature. But this is a pure space-packing/design-choice argument of the kind KSR discounted ("a court must ask whether the improvement is more than the predictable use of prior art elements according to their established functions"). It is unlikely to carry an independent claim, though it might support claim 2 as a secondary consideration if accompanied by evidence of unexpected lubricant-distribution results — no such evidence appears in the patent.

(c) Long-felt need and failure of others. The Background recites decades of difficulty with the drag brake, intensifying as indexing speeds rose. This can be a powerful secondary consideration — but it cuts both ways here. The problem was long known, and the solution was to substitute a component (the fluid-operated disc clutch) that White and the admitted art show was already available and used in this very machine class. Under KSR, a long-felt need satisfied by a known, conventional substitution is typically not enough. To rebut, the applicant would need objective evidence — e.g., that others tried fluid clutches in this location and failed, or commercial success attributable to the claimed arrangement and not to other factors. Nothing in the intrinsic record supplies that.

(d) "Tuning" hardness/softness of engagement. The specification asserts the operator "is better able to control the hardness or softness of engagement" with pneumatic clutches than hydraulic or electromagnetic ones. This is an argument about a result of the selected actuator type, and if supported by comparative data it could support claim 2. But reliance on a known actuator's known property is generally a design choice, and the specification provides no data.

Teaching away? Nothing in the retrieved record teaches away from fluid clutches for high/low speed selection; if anything, White and Index-Werke teach toward it.

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6. Conclusions

1. Independent claim 15 is the most likely to be held obvious. It is, in substance, the drive system the '819 Background admits as prior art, with the mechanical clutch replaced by the fluid-operated disc clutch that White (US 3,864,994) already discloses in a multiple-spindle machine for selecting drive speed. Combination: White + applicant's admitted prior art, with National Acme '838 as corroboration.

2. Independent claim 1 is probably obvious but presents one genuine issue — the idler gear sleeve extending both inside and outside the housing (limitation C), read together with the cages' meshing gear teeth (limitation F) and the main drive shaft gear (limitation G). The best combination is White + EMAG '752 + Weisser '267 (+ the Background admission), but I cannot evaluate the decisive teaching of '752 and '267 without their specifications, and I decline to assume it. If those references show a shaft-mounted idler sleeve with an outboard change-gear take-off, claim 1 falls; if they do not, claim 1 has a defensible position on packaging alone.

3. Independent claim 12 is claim 1's limitations plus the brake-by-clutch-engagement feature (claim 5). The "brake" function is an inherent consequence of engaging a slower-driven friction clutch into a faster-spinning load, so claim 12 adds no independent patentable weight over claim 1 in Combos A/B.

4. Dependent claims 2, 4, 5, 6, 9–11, 13, 14, 16–19 are each supported by at least one of: fluid-clutch selection (White), pressure-medium actuation and rotary locking in a multispindle automatic (Index-Werke '925), and design-choice expedients. Claim 2 (pneumatic + radial alignment) and claims 9/13/18 (the third main-drive-shaft brake) are the strongest of the dependents, but both are met by Combination C on the reasoning that converting a driven clutch into a grounded brake is a classic mechanical substitution motivated by the express secondary-machining requirement.

5. All of the "Cited By" references are post-1985 and unavailable as § 103 art. In particular, the Logan Clutch family (US 6,050,162; US 6,125,982; US 6,148,976; US 6,848,347) cannot be used against this patent. They are, however, strong evidence that the high-speed/low-speed multi-spindle drive remained an active design field — which is relevant only to background, not to patentability.

6. Uncited lead worth pursuing. My search surfaced US 4,253,359 ("Drive system for multiple spindle machine tool," filed 1979-10-24, granted 1980-09-02, now expired) — a pre-critical-date reference not listed in the '819 Prior Art section, which itself cites White '994. If its disclosure is directed to a drive system for a multiple spindle machine tool of the same class, it could be a materially closer primary reference than any cited on the face of the '819 patent. I have not verified its content and am flagging it only as an investigative lead.

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Bottom line. On the record as cited, the patent's principal inventive contribution is not the two-speed clutch-selected drive (admitted art and White), nor the use of fluid clutches (White), nor the multi-disc clutch anatomy (admitted conventional), nor the holding brake (Index-Werke). It is the specific packaging — the coaxial idler gear sleeve spanning the housing wall, the counter-rotating clutch cages with integral gear teeth, and the resulting radial-abutted clutch pair in a restricted space. Whether that packaging survives § 103 depends on disclosures in US 3,090,267, US 3,385,145, US 3,871,246, and US 4,476,752 that I was unable to retrieve, and I am explicitly not asserting what those references do or do not teach.