US 8141726

I'll run several targeted searches for this patent number, including litigation/docket checks.

Let me dig further into the claim set, litigation history, and PTAB activity for this specific number.

Summary of US 8,141,726 B2 — "Railroad gondola car structure and mechanism therefor"

1. Bibliographic data (literal, as retrieved)

Sources: https://patents.google.com/patent/US8141726/en ; https://FreePatentsOnline.com/8141726.html ; https://patents.justia.com/patent/8141726

2. Abstract (verbatim)

A railroad gondola car has a hopper carried between two trucks. The hopper has convergent end and side slope sheets that feed a bottom discharge. The bottom discharge has a pair of longitudinal doors. The car has a very short draft installation that includes a removable coupler carrier bar, and the main shear plate has a removable draft gear installation cover. The rear draft stop extends longitudinally inboard past the truck center. The couple arrangement includes an AAR Type E shank with an AAR Type F coupler. There is a machinery space above the end section shear plate. It is overhung by the slope sheet that is substantially unobstructed by any other primary structure. The pneumatic cylinder is mounted on an angle in this unobstructed machinery space, oriented longitudinally over the draft sill beneath the main drag link of the mechanical transmission, and above the main pivot of the driving input lever of the transmission. The main lever is bifurcated, and straddles the pneumatic cylinder. The lower portion of the side sheets lies laterally inboard of the stiffener web, while the upper portion lies laterally outboard of the stiffener web. The side slope sheet of the hopper meets the sidewall at the transition of the sidewall sheet from the inside-the-post to the outside-the-post condition.

3. Plain-language overview of the inventive subject matter

The disclosure is a single-hopper, bottom-discharge ("flow-through" / center-flow) gondola/ore-car design built around three interlocking themes:

(a) Very short end-of-car draft installation. The patent describes an "abnormally short" distance from truck center to striker — L88 of "less than 50 inches," with one embodiment "about 38″ (+/−2″)," and truck-center-to-coupler-pulling-face of "less than 65 inches," one embodiment "about 53″ (+/−2″)" when draft gear is fully extended in draft. This is achieved with a removable coupler carrier bar (194) slidable into slots (192) in the draft sill webs, a removable draft-gear carrier plate (174) on the underside of the draft sill, a removable cover plate (178) over an inboard aperture in the shear plate, and rear draft stops (172) that extend longitudinally inboard past the truck center. AAR Type E shank / Type F knuckle with bottom shelf, mated to short-travel draft gear (about 2½″ deflection to solid).

(b) Compact door-actuation transmission in an unobstructed end "machinery space" (75). The space is bounded by the shear plate (76), the end slope sheet (48), the central end post (80) and the corner posts (82, 84), is triangular-prismatic, and is deliberately free of "elephant ears" and other primary structure. The pneumatic actuating cylinder (260) is raised on an inclined pedestal and tilted longitudinally inboard/downward at an angle θ260 lying between horizontal and the slope-sheet angle θ48. The drag link travels predominantly parallel to (and at least instantaneously parallel to) the end slope sheet plane P48, with the cylinder sitting between the main pivot (P230) and the distal drag-link pivot (P248/P250), and below the drag link. The driven lever (262) is a bifurcated/matched pair of arms that straddles the cylinder, giving left/right symmetry: matched pivot arms (230, 232) → drag links (234, 236) → shared yoke (238) → slave links (240, 242) → knuckles (244, 246) on the left/right longitudinal doors (62, 64), which seal against each other via sprung seal members (226, 228).

(c) Two-tier door lock. A primary over-center lock (travel limiter/governor 268) prevents the doors from opening when the cylinder is dormant; a secondary latch assembly (300) — plate 304 hinged with its hinge axis parallel to the cylinder's axis of reciprocation, so it moves sideways/circumferentially rather than lengthwise — provides redundancy if the first lock fails, biased into engagement by a leaf spring (326) and deflected out of the way by cams (324, 318, and optionally 350 on the clevis).

(d) Sidewall stiffener geometry. The sidewall (34/36) spans a side sill (40) to a top chord (38). The stiffener (102) has its lower portion (104) mounted laterally outboard of the lower sidewall region and its upper portion (108) mounted laterally inboard of the upper sidewall region, with web continuity through the intermediate region (106) where the side sheet (member 94) transitions on the hopper side-slope plane P94. The side slope sheet meets the sidewall at that transition, located at a height L94 in the range ¼ to ⅔ of the sidewall height Lsw (about ⅓ in the illustrated embodiment).

4. Independent claims — plain-language overview (with an explicit caveat)

Caveat / uncertainty: the authoritative text I was given for this patent reproduces the specification (Field, Background, Summary of the Invention, Detailed Description, Abstract, classifications) but not the numbered claim set. I therefore cannot state claim numbers or exact claim language with confidence. What I can say with confidence is that the issued independent claims correspond one-to-one with the "aspects of the invention" recited in the Summary, which read as follows:

1. Drag link parallel to the end slope sheet. A hopper car with a bottom-discharge door, at least a first end slope sheet inclined downwardly toward the door, a lengthwise-oriented linkage including a drag link, and a drive to urge the door closed; wherein moving the linkage from open to closed either has the drag link's overall displacement predominantly parallel to the end slope sheet, or at least instantaneously parallel to it. (Dependent features add: first and second pivot arms on datum structure, a mechanical transmission incorporating the drag link, left/right mirror-image arm pairs with co-axial pivots, a bifurcated lever straddling the drive, a tilted actuating cylinder, the drag link between cylinder and slope sheet, and the shear-plate/slope-sheet-overhang arrangement.)

2. Tilted lengthwise actuating cylinder. A hopper car with a lengthwise door-operating linkage and a lengthwise-oriented actuating cylinder whose axis of reciprocation is tilted so displacement has a vertical component. (Dependents: cylinder on an inclined pedestal on the shear plate; axis lying in the longitudinal-vertical central plane; cylinder overhung by the end slope sheet; cylinder angle between horizontal and the slope-sheet angle; four-component closed-loop bar linkage with datum, first pivot linkage, drag link, and second pivot linkage carrying the gate; main pivot below the cylinder; cylinder between main and distal pivots in side view.)

3. First pivot arm lower than the cylinder. A hopper car with first and second end sections on trucks, a lengthwise door linkage, a lengthwise-acting actuating cylinder, a first pivot arm pivoted to the first end section at a first pivot connection, and a mechanical transmission including a drag link connected distant from that pivot — the first pivot connection being lower than the actuating cylinder in side view. (Dependent: cylinder between main pivot and distal pivot; cylinder drives an intermediate lever that drives the first pivot arm.)

4. Two-part sidewall stiffener with inside/outside transition. A hopper car with sidewalls from side sill to top chord, a predominantly upward-running sidewall stiffener between the trucks, where the stiffener's lower portion is laterally outboard of the sidewall's lower region and its upper portion is laterally inboard of the sidewall's upper region, the sidewall being continuous between them and the stiffener having web continuity. (Dependents: portions substantially co-planar and vertically aligned in section; side sheet transition region passing across the stiffener with web continuity; the sloped side sheet meeting the sidewall at that transition; transition at ¼–⅔ of sidewall height L above the side sill.)

5. Cylinder bracketed by paired linkage members. A hopper car whose door operating linkage includes a pair of first and second linkage members mounted to either transverse side of the actuating cylinder so the cylinder is bracketed between them (the matched left/right arms). (Dependents: four-component closed-loop bar linkage; drag link motion predominantly, or instantaneously, parallel to the end slope sheet; third linkage component with first and second elements co-planar with the main pivot; over-center lock preventing gate release when the cylinder is inactive; main pivot beneath the cylinder / beneath the drag link / cylinder between main pivot and drag link; drag link adjacent and parallel to the first end slope sheet.)

6. Dual lock. A hopper car with a bottom-discharge door, a lengthwise mechanical transmission, a door actuator reciprocating in a first direction, a first lock preventing door opening when the actuator is inactive, and a second lock providing redundancy, the second lock's engagement/disengagement displacement being predominantly crosswise to the actuator's reciprocation direction. (Dependents: actuator in the central lengthwise-vertical plane; second lock moving predominantly transverse to that plane; second lock hinged and pivoting circumferentially; hinge axis parallel to the lengthwise-vertical plane; spring-biased to engaged; cam / cam-follower pair arranged to deflect the second lock away as the door closes.)

7. Lock mechanism per se. A lock mechanism for a door actuating transmission of a railroad gondola car, with a body having a first fitting (mounting to datum structure), a second fitting (cam or cam follower co-operating with a transmission member), and a third fitting (an abutment obstructing the mating transmission fitting to prevent opening); the first fitting having one degree of freedom constraining the third fitting to predominantly crosswise motion, with a spring bias urging the third fitting to its blocking position. (Dependents: spring with a foot reacting against the datum structure; angular/circumferential degree of freedom; hinge axis substantially parallel to the actuator's axial direction; hinged footing with a planar footprint, the hinge axis angularly inclined relative to that footprint.)

8. Overhung machinery space free of primary structure. A hopper car with first and second end sections, a discharge section, end slope sheets feeding it, a draft sill, a main bolster, and a shear plate extending lengthwise along the draft sill and from side to side; the end slope sheet overhangs the shear plate and the car is free of primary structure directly above the shear plate under that overhang, defining a machinery space bounded by slope sheet, shear plate, end post and corner posts, with a longitudinally acting pneumatic actuator (and optionally a brake reservoir) lodged in it, and the space being free of "elephant ears." (Dependents: shear plate as upper flange of the bolster, side sill upper flange co-planar with the shear plate, side sill lower flange co-planar with the bolster lower flange, shear plate as upper flange of the draft sill.)

9. Short draft sill with removable installation fittings. A railroad freight car with a draft gear pocket, a shear plate functioning as the draft sill's upper flange, an underside access opening for inserting draft gear from below, a removable draft gear carrier plate beneath the pocket, and either an aperture in the shear plate over the inboard end region of the draft sill (letting draft gear protrude during installation) and/or a removable coupler carrier seat inboard of the striker. (Dependents: both (a) and (b); the slotted draft sill webs with a sideways-slidable retainer shaft; centerplate at truck center with rear draft stops welded inboard of truck center; truck-center-to-striker draft sill length < 50 in; truck-center-to-coupler-pulling-face < 65 in when extended in draft; short-travel draft gear with < 3 in deflection to solid; specific about 38 in and about 53 in values.)

The justia record (https://patents.justia.com/patent/8141726) shows issued claim language consistent with item 9 above, including the limitations "said freight car has a truck center to striker draft sill length of less than 50 inches," "said freight car has a truck center to coupler pulling face length of less than 65 inches when the draft gear is fully extended in draft," and "said draft gear is short travel draft gear having a deflection of less then 3 inches to solid."

5. Litigation and docket checks for 8141726

No CAFC 2026 docket and no PTAB proceeding specifically naming US 8,141,726 was found. My searches for "8141726" / "8,141,726" returned only unrelated noise (a Brazilian state trademark bulletin entry, an FDA FAERS adverse-event case number, a 2020 Complexity journal article DOI 10.1155/2020/8141726, and an FEC transaction ID). I found no infringement complaint, IPR petition, or Federal Circuit appeal identifying 8,141,726 as a patent-in-suit or challenged patent.

For context, the NSC railcar litigation activity I did find involves different patents:

• National Steel Car Ltd. v. Greenbrier-Concarril LLC, No. 24-1453 (Fed. Cir. Nov. 19, 2025) — non-precedential affirmance of an Oregon summary judgment of non-infringement. Patents asserted: US 7,434,519 and US 7,878,125 ("floor panel" / "directly mated" side-wall web limitation). Not the '726 patent. (https://www.vitallaw.com/news/patent-fed-cir-national-steel-car-s-infringement-claims-against-greenbrier-properly-dismissed/ipm01d22a2d950844444ab06e59e35d8fc5a4)
• National Steel Car Ltd. v. FreightCar America, Inc. et al., No. 1:24-cv-00594-JLH-CJB (D. Del., filed 2024-05-17) — the Rule 3 report lists only US 8,166,892 B2 and US 8,132,515 B2.
• PTAB: IPR2025-01046 (US 8,166,892); IPR2025-01047 and IPR2025-01048 (US 8,132,515) — FreightCar America, Inc. v. National Steel Car Limited, filed 2025-09-26; Patent Owner's Response filed 2026-03-13; D. Del. jury trial set for 2027-01-11.

Note that US 8,132,515 and US 8,166,892 carry the same title, share the same specification, and belong to the same NSC family as the '726 patent (the '726's sibling publication US 2010/0251922 A1 appears among its cited references). So the '726 is family-adjacent to the asserted patents, but I found no affirmative evidence it was ever asserted in the Greenbrier or FreightCar America matters. The Darts-IP "Family has litigation" flag on the Google Patents page indicates litigation somewhere in family 42666563; it does not identify the '726 patent itself, and I could not confirm which family member it refers to.

6. Confidence and uncertainty statement

• High confidence: bibliographic data, abstract, continuity (divisional of 12/559,065), priority, inventors, assignee, issue/filing dates, and the technical content of the specification (taken from the authoritative full text supplied).
• High confidence: no IPR or 2026 CAFC appeal naming 8,141,726 was located by my searches. This is a negative finding from limited search coverage — it is not proof of non-existence.
• Moderate confidence: the nine-item independent-claim outline above. It is reconstructed from the Summary-of-Invention "aspects," the abstract, and fragments of issued claim language surfaced in search results. I do not have the authoritative, numbered claim set for US 8,141,726 and cannot state how many independent claims it contains, their numbering, or their exact wording. Anyone needing claim-exact analysis should pull the granted claims directly from USPTO PatentCenter / Patent Public Search for US 12/780,741.
• I did not obtain a live USPTO PatentCenter record or a PACER/CAFC docket sheet for this number; if the "CAFC 2026 docket" check is critical, it should be re-run directly against PACER and the CAFC docket, since my search surfaced only 2025 district-court and PTAB activity.