US 6374456

I'll run the requested searches, then summarize against the authoritative patent text provided.

Let me check specifically for litigation and for the CAFC docket angle.

Summary — US Patent 6,374,456 (searched literally as "6374456")

Searches run: (1) "US patent 6374456"; (2) "6374456 patent CAFC 2026 docket"; (3) "6,374,456" Modernfold lawsuit/litigation/infringement; (4) "6374456" Court of Appeals for the Federal Circuit appeal 2026.

Litigation / CAFC finding: I found no authority tying US 6,374,456 to any Federal Circuit 2026 docket, or to any litigation at all. The searches surfaced only unrelated cases (e.g., a Samsung/MII complaint involving different patents) and patent-office journal listings. Given the patent's status (see below), a current 2026 appeal is also unlikely. I cannot confirm or deny litigation with confidence, and I found no evidence of any.

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Bibliographic data (from the authoritative full text provided)

Note on the assignment record, interpreted literally: the page lists the 2000-12-08 assignment assignors as "FORT, GEORGE E., MCROBERTS, JERALD A., OWENS, N. DOUGLAS" — Tompkins does not appear in that entry, though he is listed as an inventor. I am not treating this as an error or correcting it; it is simply what the record shows.

Abstract (verbatim)

"A track and trolley system for an operable wall panel which provides for linear motion. The track is mountable to a ceiling of a room and includes first and second surfaces. The trolley is attachable to the operable wall panel and includes first and second rotatable wheels that respectively engage the first and second track surfaces. The outer radial peripheries of the rotatable wheels and the engaged track surfaces are complementarily structured and arranged to limit movement of the first and second rotatable wheels relative to the surfaces of the track in the direction in which the axis of rotation of the track extends, while allowing the wheels to rotate about their axes of rotation and roll along the track surfaces."

Plain-language overview of the independent claims

Claim 1 — Centering + anti-float trolley on a track.
A track (ceiling-mountable) has a pair of horizontally displaced wheel-supporting surfaces plus a downwardly projecting portion. The trolley has a base plate attachable to the wall panel and a pair of wheels rotatably mounted on it. Each wheel has a first surface resting on one of the wheel-supporting surfaces, and a second surface set at an angle to the first. The wheels sit centered between the two supporting surfaces, and the track's downward projection sits between the wheels so that if a wheel is lifted off its supporting surface, it contacts the projection. Result: the wheels are kept from substantial sideways drift out of their centered position (i.e., the design resists lateral/lift displacement).

Claim 7 — Counter-rotating twin-wheel trolley with an intersection disc.
A track has a pair of wheel-supporting surfaces that are offset both horizontally and vertically, defining a channel between them, plus a soffit portion below those surfaces. A trolley bolt has a proximal end between the surfaces and a distal end running down through the channel to attach to the wall panel. A first wheel and a second wheel are both rotatably mounted on the proximal end, each supported on one of the two offset surfaces. A disc is rotatably mounted on the bolt next to the track's soffit portion, with a diameter chosen so that it prevents the wheels from becoming dislodged from the track when the trolley crosses a track intersection.

Claim 13 — Track built from a hanger bar, soffit brackets, and two contoured beams.
The track has a hanger bar (ceiling-mountable), a pair of spaced soffit brackets depending downward from it, and a pair of contoured beams attached to the hanger bar — each beam having a centrally depending first arm and a second arm next to a respective soffit bracket. The trolley has a base plate and a pair of horizontally displaced wheel assemblies. Each wheel assembly has a first peripheral surface engaging a supporting surface at the end of a respective first arm (for support), and a second surface engaging an additional, non-planar end surface of that first arm — which prevents vertical movement of the trolley.

Claim 19 — Hanger-bar/soffit track with a single contoured beam and compound wheel support.
The track has a hanger bar, a pair of spaced soffit brackets that define a channel and depend downward, and a contoured beam attached to the hanger bar with a first arm next to one soffit and a second arm next to the other. A trolley bolt's proximal end sits between the two arms, its distal end passing through the channel for panel attachment. First and second wheel assemblies are mounted on the proximal end, one supported on the end of one arm and the other on the end of the other arm. At least one wheel assembly has a "compound supporting surface" and is supported against vertical movement by two non-planar surfaces at the end of its respective arm.

Notable dependent claims

• 2: downward projecting portion of the track is triangular. 5/12/18/26: the projecting/soffit portions are integral with the wheel-supporting surfaces / hanger bar.
• 3–4, 9–10, 16–17, 24–25: complementary wheel/track shaping, including a circumferential triangular projection or a triangular groove; claim 17/25 recite a pair of juxtaposed wheels whose peripheries cooperate to form a triangular groove.
• 6: the wheels' axis of rotation extends in a "venial direction." As printed, this word appears to be a typographical error for "vertical," but I am reporting it literally and not correcting it.
• 8 / 22: the soffit portion includes bearing blocks engaging the underside of the disc.
• 11: the track has a portion engaging an upper wheel surface to centrally position the trolley bolt in the channel.
• 20: the soffits terminate in a substantially horizontal portion extending below the wheel assemblies. 23: arm ends are squared off.

Overall thrust: the invention replaces prior-art trolleys (counter-rotating tire carriers; horizontally-axled wheels) with vertically-axled wheels whose shaped outer peripheries engage complementary side-facing track contours, giving a linear-motion suspension that resists lateral forces during panel fold/unfold, prevents vertical float, and smooths passage through L-, T-, and X-intersections via a disc-and-bearing arrangement.

Uncertainty flag: I have no authoritative confirmation of any litigation, ITC proceeding, or CAFC appeal involving 6,374,456 — my searches returned nothing on point. All bibliographic and claim content above comes from the authoritative patent text supplied to me, not from a live USPTO lookup, which I was unable to complete independently.

I'll search for litigation involving US Patent 6,374,456.

The initial searches returned results about unrelated patents (the "445" patents). Let me search more precisely for US 6,374,456.

Let me search litigation databases and Modernfold's litigation history specifically.

Litigation Search: US Patent 6,374,456

Result: No litigation found

Based on my searches, I could not identify any known litigation involving US Patent 6,374,456 ("Linear motion trolley and track systems for operable walls," Modernfold, Inc., granted 2002-04-23).

What I searched

• The patent number in multiple formats ("6374456," "6,374,456," "US 6,374,456") combined with litigation, lawsuit, defendant, and docket terms
• The patent title combined with "litigation"
• Assignee-based searches ("Modernfold Inc. patent infringement lawsuit operable wall trolley")
• The requested litigation-oriented databases (Unified Patents litigation caselist, and by extension Justia/CourtListener/PACER-style query terms)

Important caution about the "445" hits

My searches for "6374456" and for the '445-series numbers returned results for entirely different patents that should not be confused with this one. These included:

• U.S. Patent 10,465,445 — a casing-flotation rupture-disc patent asserted in NCS Multistage Inc. v. Nine Energy Service, Inc., No. 6:20-cv-00277-ADA (W.D. Tex., Waco Division), with parallel PTAB proceedings (IPR2020-01615, PGR2020-00077).
• U.S. Patent 5,459,986 / the Knorr-Bremse "445 patent" — a disk-brake patent litigated in Knorr-Bremse Systeme Fuer Nutzfahrzeuge GmbH v. Dana Corp. (E.D. Va.), 183 F. Supp. 2d 848.
• U.S. Patent 5,499,671 — a Modernfold anti-float patent (same assignee, different patent).

None of these are US 6,374,456, and per the operating rule I am not treating any of them as covering this patent.

Why this is unsurprising

US 6,374,456 is a product/mechanical patent in a small, mature market (operable-wall track and trolley systems), the litigation-prone venue for which is relatively narrow. The patent's own prosecution history shows rich prior-art citation activity (24 cited references, including Bishop-Wisecarver "Dua-L-Vee" and General Bearing ball-transfer brochures, plus Modernfold's own prior patents), but citing references is not litigation.

Limitations / caveats

• I do not have direct access to PACER or to the Unified Patents litigation portal beyond what surfaced through general web search; no litigation records for US 6,374,456 surfaced in any result.
• Because I could not open the docket databases directly, I cannot state with certainty that no litigation ever existed — only that no litigation is evidenced by my searches.
• If you need a definitive answer, the reliable next steps are: (1) a direct PACER/docket search using the patent number as a keyword, (2) the Unified Patents litigation caselist, and (3) a Google Patents "Litigation" tab or Lex Machina/Docket Navigator query. I should not fabricate plaintiffs, defendants, case numbers, or outcomes that I did not actually find.

Bottom line: No litigation involving US Patent 6,374,456 is known based on the available search results.

I'll verify the structured-data finding against public sources before concluding.

Proceedings overview

Total AIA trial proceedings on file for US 6,374,456: zero (0) — no IPR, PGR, or CBM petition has ever been instituted, denied, or settled against this patent. The structured USPTO Open Data Portal block in this prompt returns no proceedings (breakdown by status: 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denied), and my independent web checks surfaced no PTAB proceeding, FWD, or Federal Circuit appeal tying this patent number to a trial — meaning the defensive posture is not "the patent has been hardened through PTAB," it is "there is no PTAB record at all, and the reason is almost certainly that the patent expired on 2020-06-30 and can no longer support a forward-looking assertion."

No proceedings to enumerate

Because the count is zero, there is no most-impactful-first ordering to build. For completeness, here is what I searched and what I found:

• Canonical source: The "PTAB proceedings on file" block supplied in this task states the ODP API returns no AIA trial proceedings as of the most recent ingest. I treat that as authoritative and did not invent a proceeding number to fill the section template.
• Web verification (2026-09-29): Queries combining 6374456 / 6,374,456 with IPR, PGR, CBM, PTAB, and Modernfold returned only (a) the patent's own Google Patents / FreePatentsOnline pages, (b) forward patent citations to '456 in later patents (e.g., US 8,033,068; US 11,376,513; US 10,213,699; US 11,920,403; US 9,682,134) — those are patent citations under "Cited By," not PTAB challenges — and (c) unrelated PTAB documents that merely happened to be co-indexed. Nothing matched a petition style (e.g., IPR20xx-xxxxx — Petitioner v. Modernfold, Inc.).
• Caveat on completeness: I could not open P-TACTS (the successor to PTAB E2E) or the PTAB API directly from this session, and very recent filings may lag public indexing. I flag this as a residual risk, not as evidence of a hidden proceeding. To close it, run a docket search at https://ptacts.uspto.gov/ and the PTAB API at https://developer.uspto.gov/ptab-api/ using "US6374456" and "6,374,456" as party/patent filters.

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Strategic summary

Claim status of US 6,374,456 (claims 1–26, all originally granted): every claim is UNTESTED before the PTAB. No claim is canceled (no IPR ever reached an FWD), and no claim has been confirmed by the Board either — so there is no PTAB-derived narrowing, and correspondingly no PTAB-derived estoppel. The patent's claim set is the original set: independent claims 1, 7, 13, and 19, with dependents 2–6, 8–12, 14–18, and 20–26. The only Office-side alterations to the record are prosecution-time prior-art citations (24 U.S. references, including US 3,661,431 to Bishop-Wisecarver — the same vendor whose DUA-L-VEE® guide wheels the specification names at the commercial-embodiment level — and Modernfold's own US 4,837,891, US 5,321,857, US 5,049,525, US 5,152,332, and US 5,499,671, plus three non-patent brochures).

Estoppel landscape: § 315(e)(2) estoppel is a non-issue — it binds only petitioners, real parties in interest, and privies in an instituted IPR. With zero petitions, no party is estopped, and every prior-art ground remains fully available to a defendant. The relevant constraint is instead statutory: § 286's six-year damages lookback. The patent's legal status is "Expired – Lifetime," with an anticipated expiration of 2020-06-30 (20 years from the 2000-06-30 filing, priority to provisional US 60/141,975 filed 1999-07-01). A complaint filed today (2026-09-29) reaches back to 2020-09-29 at the earliest — a window containing no period in which the '456 patent was in force. Infringement, by definition, cannot occur after expiration, so on these facts the entire universe of actionable past damages appears time-barred. (This is my analysis of the interplay of the expiration date and § 286, not a PTAB or court holding — verify the expiration/term-adjustment figures against the face of the patent and the USPTO Patent Center record before relying on it in a demand response.)

Pattern signals: none of the usual ones are present. No serial petitioner, no defensive aggregator (no Unified Patents / RPX-style filer in the chain), no Patent Owner appeal activity — because there has been no trial to appeal. The absence of PTAB activity on a 1999-priority patent that has been forward-cited by a dozen later patents in the operable-wall, zip-line, and fenestration spaces is itself the signal: the commercially live value in this family has moved to later Modernfold assets (e.g., the 2010-10-01-priority movable-wall-with-electrical-connections family), and '456's own enforceability window closed in 2020.

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Recommended next steps

• If you are a defendant receiving a demand that cites US 6,374,456: lead with expiration, not invalidity. Confirm on the patent's face and in Patent Center that the term ended 2020-06-30 with no term extension or reissue that would revive it. Then run the § 286 arithmetic: six years back from the complaint date lands after expiration, so no recoverable infringement period exists. Request the demand letter be withdrawn.
• Do not invest in an IPR. A petition against an expired patent buys you nothing defensible and cannot be a vehicle for prospective relief; it would also be a poor vehicle given that expiration forecloses the damages theory directly. If invalidity is nonetheless needed (e.g., for a pending case with pre-expiration conduct), note that no § 315(e)(2) estoppel attaches, so prior art — including the Bishop-Wisecarver counter-rotation art cited during prosecution (US 3,661,431) and Modernfold's own US 4,837,891 and US 5,321,857 — remains available in district court, subject to the ordinary § 282 burden.
• Close the indexing gap before you certify "no PTAB activity." Pull the P-TACTS docket and the PTAB API for both "6374456" and "6,374,456"; if either returns a hit, the analysis above changes materially and the proceeding must be added at the top of this memo with its FWD claim-by-claim disposition quoted verbatim.
• No active-proceeding milestones apply. There is no institution deadline, no oral hearing, and no statutory one-year FWD clock to track, because there is no trial. If a petition is filed after today's date, the clock starts at institution (35 U.S.C. § 316(a)(11)).

Bottom line for a defendant: there is no PTAB proceeding to defend against and no FWD to cite, and the more useful fact is the patent's 2020-06-30 expiration — not a PTAB kill, but an enforceability wall. Frame the response as "expired before the § 286 lookback window opened," not as "the claims were invalidated at the Board," because the latter would be false.

I'll research the assignment record for US 6374456 before writing up the analysis.

Assignment & Ownership Analysis — US 6374456 B1

Patent: US 6374456 B1 — "Linear motion trolley and track systems for operable walls"
App. No.: US 09/608,179 · Filed: 2000-06-30 · Granted: 2002-04-23 · Priority: 1999-07-01 (Prov. 60/141,975)
Status: Expired – Lifetime (anticipated expiration 2020-06-30; all maintenance fees paid) — this patent is unassertable today regardless of ownership.

Sourcing caveat, stated up front. The authoritative full text provided for this analysis (Google Patents) reproduces the USPTO legal-events feed for this patent. That feed discloses one recorded ownership event — the inventor-to-Modernfold assignment, recorded 2000-12-08. It does not carry reel/frame numbers, execution dates, or correspondent data, and I could not reach the USPTO Assignment Center's underlying record to pull those fields (the Assignment Center is a JavaScript application that is not readable as static HTML). I have therefore not entered any reel/frame numbers or correspondent names below, because any I supplied would be invented. Everything else is grounded in the record I do have.

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Inventors

Observations:

• Employer is determinable for all four because rights were assigned to the assignee corporation rather than to an individual/startup — the normal pattern for a ~75-year-old manufacturing incumbent with an in-house engineering department.
• One anomaly worth flagging, without over-reading it: the Google Patents legal-events entry for the 2000-12-08 recorded assignment names only Fort, McRoberts, and Owens as assignors. Tompkins does not appear as an assignor in that entry. That is not evidence of a defect — the most likely explanations are (a) a separate/parallel assignment instrument for Tompkins, (b) coverage by a pre-existing employment agreement, or (c) truncation of the assignor list in the Google Patents summary. I cannot distinguish among these without the underlying reel/frame image. If you need certainty, pull the assignment image from the reel cited on the Assignment Center detail page.
• No inventors-departing-within-12-months pattern. The tell-tale "mass exodus preceding a fire-sale" signal is affirmatively absent: N. Douglas Owens resurfaces as a named inventor on a later Modernfold filing, US 2006/0248826 A1 ("Soffit assembly for moveable wall system and removal tool therefor," filed 2005-05-05), and also appears as an assignor on the 2000-12-08 record. That is a ~5-year continuity of employment post-filing — the opposite of an exodus.
• The patent itself cites a long chain of Modernfold-internal prior art (US 4837891, 5042555, 5152332, 5329857, 5339881, 5358023, 5467559, 5499671, plus USD 335624) and third-party art from American Standard, Advanced Equipment Corp., Hough Mfg., Hufcor, Dorma-Glas, Bishop-Wisecarver, General Bearing. This is a densely populated, decades-old, in-house R&D lineage — a signature of a genuine operating manufacturer, not a patent-acquisition vehicle.

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Original assignee

Modernfold, Inc. (original and, per Google Patents, current assignee).

• Primary line of business: design and manufacture of operable partitions / movable wall systems, plus glass wall systems and accordion doors. Products include the Acousti-Seal operable partition line and continuously-hinged electric partitions. Roughly 156 employees; HQ 215 West New Road, Greenfield, Indiana 46140.
• Did they ship a product embodying the claims? Highly consistent with yes, but I have not independently verified a specific SKU against the claim language. The specification describes the claimed vertical-axis, counter-rotating guide-wheel trolley running on squared-off track legs as the actual production architecture for Modernfold's top-hung panels (FIGS. 1, 3, 13–14), and the commercial Acousti-Seal line is a top-hung operable partition system. Treat "product embodying the claims" as probable but unverified at SKU level.
• Current status: Operating, as a subsidiary/brand within the dormakaba Group (formerly Dorma). Modernfold, Inc. was acquired by Dorma on 2002-02-20 — i.e. approximately two months before this patent issued (2002-04-23). Marketed today as "Modernfold, a dormakaba Group company."
• Nature of the acquisition — important for the assignment analysis: the acquisition was a stock/equity purchase of the operating company, not an asset or IP divestiture. The seller's motivation, per the deal intermediary, was that "the company's primary shareholder was an offshore insurance company that was liquidating its U.S. holdings." A change of control of that kind is not recordable at the USPTO, which is exactly why no assignment to Dorma/dormakaba appears — and why Modernfold, Inc. remains the assignee of record to this day. Do not misread the absence of a Dorma assignment as an ownership gap.

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Assignment timeline

Recorded ownership events for US 6374456 (App. 09/608,179) — from the USPTO legal-events feed as reproduced in the source:

• Executed date not disclosed in source / recorded 2000-12-08 — Reel/Frame: NOT RETRIEVED (see caveat above; the source does not expose reel/frame, and I will not guess one)

  • Conveyance: Assignment of Assignors' Interest ("ASSIGNMENT OF ASSIGNORS' INTEREST — SEE DOCUMENT FOR DETAILS")
  • Assignor(s): George E. Fort; Jerald A. McRoberts; N. Douglas Owens (Melvin W. Tompkins named on the patent as inventor but not listed as an assignor in this entry)
  • Assignee: Modernfold, Inc.
  • Correspondent: not retrievable — the source feed does not carry the correspondent/recording-attorney field. No recurrence can be assessed, because no correspondent string is available for any entry.
  • Context: Initial prosecution-stage assignment — inventors conveying rights to their corporate employer, standard for a large manufacturer.

• No further recorded assignment. There is no recorded conveyance to Dorma, to dormakaba, to any IP-holding affiliate, to any licensing entity, or to any third party. The chain is one link long and terminates at the original operating manufacturer.

Related events for context (not assignments):

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Timeline diagram

timeline
    title Ownership of US 6374456
    1999 : Provisional filed Jul 1
    2000 : Non-provisional filed Jun 30
         : Inventors assign to Modernfold Inc
    2002 : Modernfold acquired by Dorma Feb 20
         : Patent granted Apr 23
    2020 : Patent expires Jun 30

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NPE / troll-pattern signals

Net signal count: zero present, one data gap (correspondent), one patent that is already expired. There is no NPE footprint to characterize.

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Verdict

Insufficient data

This is the rubric's "only the original assignment" case, and it is the benign variety. Exactly one ownership record exists — the 2000-12-08 inventor-to-Modernfold, Inc. assignment — and no post-issuance transfer of any kind is recorded; the patent remained with its original operating manufacturer through its 2020-06-30 expiration and is today Expired – Lifetime and unassertable. All eight NPE signals come back not present on the evidence available, with the single caveat that the correspondent field was not retrievable from the source I could reach, so signal #3 is a data gap rather than a clean negative — though it is immaterial given a one-link chain.

The one ownership event that does sit near the patent's commercial life — Modernfold's 2002-02-20 acquisition by Dorma — was an equity purchase that is not recordable at the USPTO, which explains the absence of any Dorma/dormakaba assignment and should not be mistaken for missing data. Verdict would move to "Operating-company assertion" only if you separately surface an infringement suit by Modernfold/dormakaba against an actual competitor; none was found, and the patent's expiry forecloses that prospect.

Verify at: USPTO Assignment Center — search by patent number 6374456 or application 09/608,179; mirror index at assignment.uspto.gov/patent. Pull the reel/frame image for the 2000-12-08 record to recover the (a) execution date, (b) full assignor list — confirm whether Tompkins executed, and (c) correspondent of record, which is the field I could not obtain here.

I'll research the cited prior art for US 6,374,456 to provide accurate citations, dates, and claim-level anticipation analysis. Let me start with the most technically relevant references.

Let me research the remaining key prior art references.

Prior-Art Analysis — US 6,374,456 B1

1. Confirmation of the record searched

I searched for the literal identifier 6374456 and confirmed the target is US 6,374,456 B1, "Linear motion trolley and track systems for operable walls," application US09/608,179, filed 2000-06-30, granted 2002-04-23, priority to provisional 60/141,975 (1999-07-01), assignee Modernfold, Inc. (New Castle, IN). Inventors: George E. Fort, Jerald A. McRoberts, N. Douglas Owens, Melvin W. Tompkins. The front-page PDF confirms this record and its cited references. I found no evidence that "6374456" maps to any other patent, and I am not importing the unrelated "445-series" hits (U.S. 10,465,445, the Knorr-Bremse '445 patent, etc.) noted in the earlier litigation section — that caveat still stands.

2. Method and evidentiary caveat (read before the § 102 conclusions)

• The patent lists 24 U.S. patent citations (all cited by the examiner, none by third parties per the Google Patents page) plus 3 non-patent citations.
• I retrieved full/fuller text for the most technically relevant references (US 3,661,431; US 4,401,033; US 4,837,891; US 5,329,857; US 3,708,916) and bibliographic data for all 24. For the remainder I could pull only the citation metadata (title, assignee, filing/publication dates), which are reproduced verbatim from the patent record.
• § 102 is a single-reference test. A reference anticipates only if it discloses every element of a claim as arranged. Several of the references below teach individual elements of claims of the '456 patent (most importantly the wheel/track geometry) but not the full claimed combination, which centers on a V-grooved wheel turning on a vertical axis and straddling a complementary track contour that centers the wheels between two horizontally displaced supporting surfaces for a suspended operable-wall panel. My "potentially anticipates" entries below therefore flag the strongest candidates and are explicitly qualified where full text was unavailable. No reference should be treated as a clean anticipatory disclosure of the independent claims without element-by-element verification against the full document.

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3. The most relevant prior art (detailed)

A. US 3,661,431 A — Wisecarver, "Guide wheels and tracks" (Bishop-Wisecarver Corp.)

• Filing: 1970-08-24 · Grant: 1972-05-09 · (6 claims). Also cited as the "Dua-L-Vee" commercial line.
• Description: A guide wheel whose outer radial periphery is formed as a double-V — a central annular guide channel of substantially V-shaped cross-section with sides at 90°, plus outer inclined surfaces at 90° to the inner walls — so the wheel can ride either within a track's 90° apex or straddle the outside of the rail. Includes eccentric adapter bushings for precision fit-up. The spec expressly covers a pair of wheels guiding a track on the outside of the pair, and a track positioned between two wheels (Figs. 6–9).
• Relevance to '456: This is the single closest structural teaching of the wheel-periphery/track-contour complementarity that is the core of the '456 independent claims. Compare '456 wheel assembly 38 (upper bevel 60, V-groove 62, lower bevel 64) and track surfaces 72/73 at 90°.
• Potential § 102 impact: Claim 4 ("circumferential, triangular projection"), claim 10, and the triangle-groove/bevel limitations of claims 16 / 24 / 25 are strongly suggested by this reference. However, because it discloses a linear-guide wheel/rail, not a panel-suspending trolley with a base plate, pendant bolt, and downwardly projecting centering portion, it does not anticipate independent claims 1, 7, 13 or 19 as wholes. Treat it as the primary § 103-type teaching reference rather than a standalone § 102 bar.

B. US 4,401,033 A — Gerken, "Counter-rotating trolley and track suspension system" (American Standard Inc.)

• Filing: 1981-06-10 · Grant: 1983-08-30.
• Description: A self-plumbing, counter-rotating trolley for an operable wall panel: a pendant bolt carries a pair of counter-rotating discs mounted on a common vertical axis; the track has vertically spaced, diametrically arranged rails. Discs and rail-contacting surfaces are spherically formed from a common centerpoint but unequal radii so the discs "always maintain mating contact" even under misalignment.
• Relevance to '456: Teaches the two-counter-rotating-elements-on-a-vertical-pendant-bolt architecture (same family as '456's wheels 38/48 and 184/188) and the goal of keeping the trolley centered in the track.
• Potential § 102 impact: Relevant to the two-wheel/vertical-axis aspects of claims 1, 6, 7. But its contact surfaces are disc rims on flat/cylindrical rails, not a V-groove/beveled wheel straddling 90° surfaces, and there is no "downwardly projecting portion" between the wheels engaging the wheels' angular surfaces. It does not anticipate claims 1–6 or 7 as a whole; it is a counter-rotation prior-art reference under § 103.

C. US 4,837,891 A — Toma & Owens, "Track and trolley with dual drive wheels having annular track engaging surfaces of different diameters" (Modernfold, Inc.)

• Filing: 1987-06-11 · Grant: 1989-06-13.
• Description: Same-assignee system: a track with a lower rail and a higher rail, and a trolley with two coaxially-mounted drive wheels of different annular diameters that independently counter-rotate; includes slide pads at track intersections (X/T/L/Y) to reduce elevational drop.
• Relevance to '456: Directly relevant to the intersection behavior that '456 addresses via disc 174 (claim 7) and to the dual-wheel-on-a-shaft arrangement (claims 1, 7).
• Potential § 102 impact: Pertinent to claims 1 and 7; however, its wheels are flat annular rims of unequal diameter on horizontal rails, not beveled V-groove wheels, and its intersection solution is slide pads, not a diametrically-sized disc (claim 7 element). It does not anticipate the V-groove/centering combination.

D. US 3,708,916 A — "Movable wall panel systems" (American Standard Inc.)

• Filing: 1971-04-23 · Grant: 1973-01-09.
• Description: A panel trolley with two pairs of rollers at right angles, plus a low-friction support platform (yoke) so that when a trolley crosses a right-angle track intersection, the platforms engage the track edges and prevent the rollers from dropping deep into the crossing slots — i.e., it solves the same "trolley hangs up / must be lifted at intersections" problem that '456's specification identifies as a drawback of prior art.
• Potential § 102 impact: Relevant to the intersection-dislogment element of claim 7. But the mechanism is a platform/strut yoke, not a rotatable disc adjacent a soffit "diametrically sized to prevent dislodgment." Not anticipatory.

E. US 5,329,857 A — Owens, "Track switch for suspended movable wall panels" (Modernfold, Inc.)

• Filing: 1992-12-22 · Grant: 1994-07-19.
• Description: A motorized/actuated track switch with a diverter movable between first/second positions to route trolleys through intersecting tracks; the switch includes biasing and limit-switch feedback. Cited on the '456 front page.
• Relevance to '456: Background on track intersections/switch geometry context of the '456 intersection embodiments (Figs. 22–34). It discloses trolley-through-intersection routing but not the '456 wheel/track wheel-centering structure or the disc/soffit bearing-blocks (claims 7–8, 21–22).
• Potential § 102 impact: Background art; no independent claim of '456 is anticipated.

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4. Full citation list of all 24 examiner-cited references

Dates are filing → publication/grant as shown in the patent record. "Description" is brief; where marked (*) I retrieved fuller text, otherwise the description is from the title/assignee metadata.

(Numeric identifiers above are reproduced exactly as they appear in the patent/Google Patents record; I have not auto-corrected any of them. Note the patent record itself shows the grant number for item 23 as "US5522445A," consistent with the citation list.)

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5. Claim-level § 102 assessment (summary)

Grouping the '456 claims by inventive concept and naming the strongest single-reference candidate:

• Claims 1–6 (V-grooved centering wheel on vertical axis between horizontally displaced track surfaces, with downward projection). No single cited reference discloses the whole. US 3,661,431 discloses the V-groove wheel + 90° track but not the suspended-panel trolley or the downwardly projecting centering portion between a pair of wheels. US 4,401,033 / 4,837,891 disclose counter-rotating dual wheels on a vertical bolt but not the complementary V-groove/centering geometry. Best anticipatory candidate: none as a whole; strongest element-level teaching: US 3,661,431 (claims 3, 4, 6 partially).
• Claim 7 (dual counter-rotating wheels on a bolt + soffit-located disc sized to prevent dislodgment at intersections). Elements are scattered: counter-rotating wheels (US 4,401,033; US 4,837,891), intersection non-dislodgment (US 3,708,916; US 4,159,556), carrier disc (US 5,181,296). No single reference anticipates; strongest partial: US 3,708,916 for the intersection element.
• Claims 8, 22 (bearing blocks/ball transfers under the disc). Not taught by any cited patent; the closest art is the General Bearing Corp. ball-transfer brochure (see § 6), which is a commercial catalog, not a patent.
• Claims 9, 10, 16, 17, 24, 25 (wheel-periphery shaping; juxtaposed twin wheels forming a triangular groove). US 3,661,431 is the closest prior art (double-V wheel; outside surfaces at 90°; plural wheels straddling a track). These dependent claims are the ones most exposed to a § 102/§ 103 challenge on this reference.
• Claims 13–15, 18–20, 23, 26 (hanger-bar/soffit-bracket/contoured-beam track architecture; squared-off arm ends; integral soffits). These are track-construction claims; the cited Modernfold/Advanced Equipment track patents (US 4,837,891; US 5,063,636; US 5,481,840; US 5,603,192) show related hanger/soffit architectures but not the specific "contoured beam with centrally depending first arm + second arm adjacent a soffit bracket" engaged by a compound wheel surface. No clean anticipatory reference identified.
• Claim 11, 21 (track portion engaging a wheel upper surface to center the trolley; disc at intersections). Centering concept appears in US 4,401,033 (self-plumbing); intersection support in US 3,708,916 / US 4,837,891. No single anticipatory reference.

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6. Non-patent literature cited (all examiner-cited)

1. Bishop-Wisecarver Corp., Pittsburg, CA — "The Dua-L-Vee System: Three Components, Four Sizes" brochure (Jan. 17, 1993). Key commercial-art reference: this is the vendor literature for the wheel assemblies the '456 patent expressly identifies as suitable ("DUA-L-VEE® guide wheels," Bishop-Wisecarver Corp. of Pittsburg, CA). It corroborates that the V-groove wheel technology was known and commercially available pre-priority, and is the most likely basis for an anticipation/obviousness attack on the wheel-periphery claims (3, 4, 9, 10, 16, 24, 25).

2. Bishop-Wisecarver Corp. — "The Natural Selection In Linear Motion: Product Overview" brochure (Jan. 17, 1996). Companion catalog; general linear-motion component art.

3. General Bearing Corp. of New York — "Ball Bearings, Ball Transfers, Thrust Bearings" brochure (Jan. 17, 1980). Corroborates the pre-1980 availability of ball transfers and thrust bearings — directly relevant to '456's thrust bearing 32/103 and the switch's ball-transfer bearing assemblies 320 (claims 8, 22). A § 102 attack on claims 8/22 based on this brochure alone would fail (the brochure doesn't disclose the track/trolley combination), but it is strong § 103 evidence.

(Note: the January 17 date stamps on these brochures are the database's recorded citation/print dates; they should be verified against the original documents before being relied on as § 102(b) art.)

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7. Bottom line

• The most relevant prior art is US 3,661,431 (Bishop-Wisecarver "Guide wheels and tracks"), supported by the Bishop-Wisecarver "Dua-L-Vee" brochure and General Bearing ball-transfer brochure. Together they teach the V-groove wheel/track complementarity and the bearing components that the '456 patent relies on — but none anticipates the full claimed combination of a vertically-axis V-grooved wheel straddling complementary track surfaces on a suspended operable-wall trolley, with the downwardly projecting centering portion and the intersection disc.
• The '456 patent is best characterized as a combination invention. The cited art individually teaches (i) V-groove guide wheels (US 3,661,431), (ii) counter-rotating dual elements on a vertical bolt (US 4,401,033; US 4,837,891), and (iii) intersection/drop-through solutions (US 3,708,916; US 4,159,556; US 4,837,891) — so the realistic invalidity theory is § 103 obviousness over these references in combination, not § 102 anticipation by any one reference.
• Highest-risk claims to a § 102/§ 103 challenge: the wheel-periphery dependent claims (4, 10, 16, 17, 24, 25) in view of US 3,661,431 + the Dua-L-Vee brochure.
• Lowest-risk claims: the hanger-bar/soffit/contoured-beam track claims (13–15, 18–20, 23, 26) and the disc-with-bearing-blocks intersection claims (8, 22) — no cited patent discloses the specific combination.

Limitations: I was able to retrieve full or substantial text for five of the 24 references (US 3,661,431; US 3,708,916; US 4,401,033; US 4,837,891; US 5,329,857); the descriptions for the remaining references rely on their titles, assignees, and citation metadata, and should be confirmed against the full documents before any anticipation conclusion is finalized. I did not independently verify each reference's § 102(b) critical date; all are U.S. patents pre-dating the '456 priority date of 1999-07-01, so they are at least § 102(a)/(b) prior art on their face.

I'll ground the § 103 analysis by verifying what the key cited references actually disclose. Let me pull the most analytically important ones.

Let me pull a few more of the cited references that bear directly on the track/soffit and intersection claims.

Obviousness Analysis — U.S. Patent 6,374,456 B1 under 35 U.S.C. § 103

Built on the prior sections: I rely on the previously generated claim chart/overview (claims 1, 7, 13, 19 independent; 26 claims total) and do not repeat it. Where the analysis below depends on the reference list from the patent's own "Citations (24)" and "Non-Patent Citations (3)" sections of the Google Patents page, I say so.

Status of my evidence (read this first). This is a prosecution-style / IPR-style prima-facie analysis, not a validity opinion or a legal conclusion. I retrieved the full text or substantial text of US 3,661,431; US 4,401,033; US 5,491,671; US 5,181,296; EP 0 435 583 B1; US 5,329,857 and the Bishop-Wisecarver "DualVee" literature, plus the '456 specification itself. Four of my searches for US 4,159,556, US 4,837,891, US 5,603,192 and US 5,063,636 were cut off by a tool step limit, so my characterizations of those four come from titles, contemporaneous secondary sources, and the "Background"-type statements the '456 and the Gerken patent make about them, not from their full text. I flag every such inference below. Do not treat any reference description here as a substitute for reading the reference.

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1. Legal framework applied

The claims have an effective filing date of 1999-07-01 (provisional 60/141,975); issued 2002-04-23. All 24 patent citations and all 3 non-patent citations are earlier than the critical date and qualify as prior art under § 102(b) (the latest is US 5,603,192, 1997-02-18).

I apply the KSR v. Teleflex framework (550 U.S. 398 (2007)): a claim is obvious where the differences between the claimed subject matter and the prior art are such that the subject matter "as a whole would have been obvious"; the TSM test is one permissible rationale among several, not the exclusive test. The rationales I invoke are:

• (A) Known elements combined by known methods → predictable result.
• (B) Simple substitution of one known element for another.
• (C) Known technique used to improve a similar device in the same way.
• (D) Known technique applied to a known device "ready for improvement."

Critically for this patent, the applicant's own specification supplies much of the motivation (admitted prior art / "AAPA"). Under In re Fritch and KSR, admissions in the specification about what the prior art taught and what problems it had are usable against the claims.

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2. Person of ordinary skill in the art (POSITA)

A mechanical engineer (or designer) with a bachelor's degree in mechanical engineering and roughly 3–5 years of experience designing overhead track-and-trolley or guided linear-motion systems, or equivalent, familiar with: (i) roller/guide-wheel linear motion components (V-wheel/rail systems), (ii) counter-rotating operable-wall carriers, and (iii) track-rail/soffit ceiling construction. This is a mechanical-arts, off-the-shelf-component field with a low bar for combination.

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3. Prior-art landscape mapped to claim elements

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4. Claim 1 — the core linear-motion trolley

Claim 1 requires: a ceiling-mountable track with (i) a pair of horizontally displaced wheel-supporting surfaces and (ii) a downwardly projecting portion; a trolley with a base plate and a pair of wheels; each wheel having a first surface on a supporting surface and a second surface angularly oriented to the first; wheels centered between the supporting surfaces; and the downward projection between the wheels engaging the second surfaces when the wheels are lifted, preventing substantial movement from center. (In the specification this is the FIG. 9 embodiment — right-triangular wheel peripheries 38′/48′ and the "downward track projection 165, which is right triangular in shape.")

Primary combination: US 3,661,431 (Wisecarver) in view of the Bishop-Wisecarver Dua-L-Vee NPL, in view of US 4,401,033 (Gerken).

• US 3,661,431 discloses the two angularly-related peripheral surfaces (its V-groove walls and its outer V-apex walls, all at 90°) and a track presenting two right-angle surfaces, and expressly places "the guide tracks between the wheels" (FIGS. 8–9). That is the structural heart of claim 1.
• The Dua-L-Vee NPL supplies the base plate carrying plural wheels (the BWC "Wheel Plate Assembly … including four DualVee guide wheels") and supplies the very wheels the patent admits it uses — an admission that the claimed wheel structure is prior art.
• US 4,401,033 (Gerken) supplies the operable-wall trolley context: a pendant-bolt trolley on a ceiling track, two counter-rotating wheels on one shaft, and a track with spaced rails.

Motivation (why a POSITA would combine): The '456 Background itself states the goal — "linear motion … panels … movable in a smooth and relatively easy fashion" — and criticizes the prior art for (a) axial-surface/stacked-tire contact and (b) horizontal-axis wheels that are forced sideways by lateral loads during unfolding. Applying an established linear-motion guide-wheel/rail technology (BWC DualVee, an admitted "industry standard") to the known overhead operable-wall trolley is rationale (C)/(D): use of a known technique (V-wheel-on-rail guidance) to improve a similar device (an overhead track suspension) in the same way, with a predictable result (smoother, self-centering travel). It is also rationale (B): substituting the known V-wheel/track interface for the known tire/disc-on-ledge interface.

Reasonable expectation of success: High. The wheel is a catalog part; the patent reports no unexpected result beyond "smooth." Nothing in the claimed geometry (right-angle surfaces interacting with angled wheel faces) is beyond routine mechanical skill.

Dependent claims under claim 1:

• cl. 2 (downward projection "triangular"): met by Wisecarver's 90° V corner / US 3,552,474 "Diamond roller."
• cl. 3–4 (complementary peripheral shaping; "circumferential, triangular projection"): squarely US 3,661,431 (apex formed by outside inclined surfaces) and the DualVee profile.
• cl. 5 (projection integral with supporting surfaces): routine manufacturing choice; also shown by one-piece rolled/extruded track art (US 4,401,033 rolled sheet; US 4,837,891).
• cl. 6 ("axis of rotation extending in a venial direction" — reported literally; the word appears to be a typographical error for "vertical"): if construed as vertical, the vertical-bolt trolleys of US 4,401,033 and US 5,181,296 meet it.

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5. Claim 7 — twin wheels + intersection disc

Claim 7 requires: a ceiling-mountable track with a pair of wheel-supporting surfaces horizontally and vertically displaced, defining a channel, plus a soffit portion below; a trolley bolt whose proximal end is between the surfaces and distal end passes through the channel to the panel; first and second wheels on the proximal end, each on one surface; and a disc rotatably mounted on the bolt adjacent the soffit, diametrically sized to prevent dislodgment of the wheels when traversing a track intersection.

Primary combination: US 5,181,296 (Hufcor/Williams) [or its EP 0 435 583 B1] in view of US 3,661,431 (Wisecarver) / DualVee NPL, in view of US 4,159,556 (Advanced Equipment) or US 4,837,891 (Modernfold).

• US 5,181,296 / EP 0 435 583 B1 discloses two discs on one vertical bolt, a track whose ledges are "spaced apart horizontally and vertically," the bolt moving "in the slot between the track ledges" (the claimed channel), discs that counter-rotate, and an express object of minimizing "hang-ups at intersections" with a masking ledge occupying the intersection gap. This is a near-element-for-element read of the track/bolt/channel/two-wheel architecture of claim 7.
• US 3,661,431 / DualVee converts the Hufcor flat/angled-rim discs into the claimed contoured wheels — rationale (B), a simple substitution of a known wheel for a known wheel to obtain better anti-friction guidance.
• US 4,159,556 (and, secondarily, US 4,837,891's "slide pads at track intersections") supplies the anti-dislodgment-at-intersection function of the disc, and Gerken's own background characterizes US 4,159,556 as negotiating a junction without dislodgment — third-party corroboration that the problem and a solution were known.
• The soffit is conventional ceiling-suspension structure, shown throughout the cited operable-wall track art (US 4,837,891; US 5,063,636; US 5,603,192; US 4,401,033's soffit/clip arms).

Motivation: the '456 Background admits the prior counter-rotating carrier "tend[s] to get hung up or jam" at intersections, forcing the user to lift the panels. That is a classic "known problem in the field" motivation (KSR rationale (D); cf. the "long-felt need" thread in Hufcor's and Gerken's stated objectives). A POSITA adding a disc on the bolt sized larger than the intersection gap to keep the wheels engaged is an obvious, mechanically trivial fix — indeed it is the same fix Hufcor's masking ledge performs.

Dependent claims 8 / 22 ("bearing blocks engaging an underside of said disc"): met by the General Bearing ball-transfer NPL (off-the-shelf ball transfers) combined with US 5,329,857 / intersection hardware; a POSITA seeking low-friction disc support at a switch would reach for a ball transfer.
cl. 9–10, 16–17, 24–25: as in §4 — Wisecarver/DualVee.
cl. 11 (track portion engaging an upper wheel surface to centrally position the bolt in the channel): Wisecarver's right-angle track geometry inherently centers the wheel/track interface laterally; and Hufcor's "engagement of the discs with ledges on opposite sides of the bolt supports the bolt in an upright position."
cl. 12 (soffit integral with supporting surfaces): routine; shown by the one-piece extruded/rolled track art cited.

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6. Claims 13 and 19 — the hanger-bar / soffit-bracket / contoured-beam track

Claim 13 claims a track of a hanger bar + a pair of spaced, downwardly depending soffit brackets + a pair of contoured beams, each beam having a centrally depending first arm and a second arm adjacent a soffit bracket; plus a trolley with a base plate and horizontally displaced wheel assemblies, each with a first peripheral surface on an arm end and a second surface engaging an additional, non-planar arm-end surface to prevent vertical movement.
Claim 19 is the same architecture with a single contoured beam whose two arms sit by the two soffits, plus a compound-support wheel assembly supported against vertical movement "by two nonplanar surfaces at said end of a respective one of said arms."

Primary combination: US 4,401,033 (Gerken) in view of US 3,661,431 (Wisecarver)/DualVee, in view of the soffit/hanger-bar track art (US 4,837,891; US 5,063,636; US 5,603,192; US 4,159,556).

• US 4,401,033 discloses a track rolled from one sheet with inturned, vertically spaced rails plus a bracket with depending arms and hanger rods — i.e., a hanger bar carrying contoured, downwardly extending, laterally displaced track members, exactly the genus of claims 13/19. Its curved (cylindrical/spherical) rail surfaces are "non-planar" surfaces.
• US 3,661,431 teaches that a track must present two surfaces at right angles to engage the wheel ("squared-off ends," cl. 15/23), and that the wheel can ride on the enclosed groove or straddle the outside surfaces — reading on the claimed two non-planar surfaces at one arm end (cl. 13's "additional first arm end surface, non planar with said supporting surface"; cl. 19's "two nonplanar surfaces").
• The soffit-bracket-and-gypsum-panel ceiling assembly is conventional and appears across the cited track art (and is described in the '456's own FIGS. 5–8, 19–20 as known structure).

Motivation: claims 13/19 are essentially track-profile housekeeping — packaging known wheel-engaging surfaces into a hanger-bar/soffit extrusion. The leading rationales are (A) known elements combined by known methods (a hanger bar, soffit brackets, and a profiled track member are each old; assembling them is routine) and (C) improving a similar device in the same way (giving an operable-wall track the two-non-planar-surface wheel support that Wisecarver-type wheels require). The '456 specification itself describes these track variants as alternatives to one another (FIGS. 3–9, 19–21), undercutting any argument that the combination was non-routine.

cl. 18 / 26 (soffits integral with hanger bar): routine one-piece forming; supported by the extruded/rolled one-piece track art cited.
cl. 20 (soffits terminate in a horizontal portion below the wheels): Hufcor's masking ledge ("some operational function at the intersections," below the disc) and conventional soffit flanges.

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7. Consolidated motivation-to-combine showing (KSR)

1. Same field, same problem, same solution class. Every reference is in overhead-suspension for operable walls/doors or in guided linear motion. There is no non-analogous-art hurdle.
2. The specification admits the problems and the components. The '456 Background identifies the exact deficiencies (axial-surface tire carriers; horizontal-axis wheels thrown sideways; intersection jams; need for centering rollers) that the cited art attacked, and the spec admits using Bishop-Wisecarver Dua-L-Vee wheels — i.e., concedes the claimed wheel structure is a purchased prior-art part.
3. A third party (Gerken) independently documents one of the objects — US 4,159,556's junction negotiation "without dislodgment" — corroborating that claim 7's anti-dislodgment disc answers a recognized need.
4. Predictable results. All claimed benefits (smoothness, self-centering, no vertical float, no intersection jams) are the expected consequences of the known V-wheel/rail and disc-at-intersection expedients; the spec reports nothing surprising.
5. Design incentives / finite number of solutions. The track profile, wheel geometry, and hanger/soffit packaging are a closed set of mechanical options; KSR's "predictable variation" and "obvious to try" doctrines apply.

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8. Where the § 103 case is weakest (candor)

• Literal element gaps. I have not located a single reference that literally shows, in one figure, a ceiling-mounted operable-wall track with a downwardly projecting portion between two wheels that engages the wheels' angled faces on lift (claim 1's exact geometry), nor a reference showing the claim 7 disc expressly "diametrically sized to prevent dislodgment." Those are functional/geometric limitations that a patentee would argue are only met by hindsight assembly of the references. My case rests on the combined teachings, not on anticipation.
• Contrary-disc-shape teachings. Gerken and Hufcor use spherical/angled-rim discs on ledges, not V-groove wheels on corners. That is a difference in kind, though not a "teaching away."
• Four unread references. My descriptions of US 4,159,556, US 4,837,891, US 5,603,192, US 5,063,636 are from titles/secondary sources; if any of those discloses the claim 1 or claim 7 geometry, the analysis strengthens; if they disclose less, weakness (a) grows. Verify before relying on this analysis in a real filing.
• Prosecution history unknown. The SUMMARY describes a "means on the track and the trolley for rollingly engaging" claim, but no issued independent claim is in means-plus-function form — the granted claims 1/7/13/19 recite structure. That strongly suggests amendment during prosecution (possibly to overcome § 112 or prior art). I could not retrieve the file wrapper, so I cannot say what art the examiner overcame or why. That history could cut either way.
• Secondary considerations unexamined. No evidence of nexus-bearing commercial success, long-felt need, failure of others, or copying was verified. If Modernfold can show nexus between the claimed linear-motion design and commercial success (e.g., its "Smart Track"/COMPACTLINE product lines appearing in secondary sources), that could rebut a prima facie case.

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9. Bottom line (hypothetical)

On the present record, a prima facie case of obviousness can be made, at least, for:

• Claim 1 over US 3,661,431 + DualVee NPL + US 4,401,033 (and cl. 2–6 likewise);
• Claim 7 over US 5,181,296 / EP 0 435 583 B1 + US 3,661,431 (or DualVee NPL) + US 4,159,556 or US 4,837,891 (and cl. 8–12 with the General Bearing NPL and US 5,329,857);
• Claims 13 and 19 over US 4,401,033 + US 3,661,431 + conventional soffit/hanger-bar track art (and cl. 18/20/26).

The strongest obviousness theory is not claim 1 but claim 7, because US 5,181,296 supplies almost the entire track-bolt-two-wheel-channel architecture and expressly targets the same intersection "hang-up" problem. The weakest is the exact "downward projecting portion engages the second surfaces on lift" limitation of claim 1, which is functional and depends on combining references rather than on a single explicit disclosure.

All of the above is an analytical prima-facie showing, not a conclusion of invalidity; the patent was granted over this art, and no litigation or PTAB challenge to US 6,374,456 was found (per the earlier litigation section), so there is no adjudicated record on these questions.