Invalidity dossier
US 139055
Improvement in governors
Added 9/23/2026, 7:47:15 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 139,055
Title: Improvement in Governors
Inventor: Robert W. Gardner, of Quincy, Adams County, Illinois
Patent Number: US 139,055
Application Filed: February 1, 1873
Granted/Published: May 20, 1873
Anticipated Expiration: May 20, 1890
Legal Status (as listed): Expired – Lifetime
Assignee: None stated in the supplied text.
Purpose
The patent addresses steam-engine governors in which a valve is opened by a weighted lever under the action of centrifugal balls and closed by the balls. Gardner sought to improve safety and responsiveness when the governor's driving belt breaks or slips off its pulleys.
Plain-Language Scope (Three Stated Parts)
Stop-motion on belt failure. Instead of the common arrangement—where falling balls close the valve against a separate seat, requiring the valve to open fully first and travel a long distance—Gardner provides a fulcrum for the weighted lever that can be released ("let fall") and is tripped when the belt breaks, so the valve closes directly on its working seat. The frame carrying the balls is made to turn on the top plate, with an arm holding the fulcrum up; belt strain maintains this position, and loss of that strain lets the arm swing back and the lever drop.
Durable valve-seat and valve facing. A valve-seat of hardened steel or "American sterling metal" is secured without screw-threads by seating it in a rabbet in the casting and clamping it with a spider fitted in a reverse rabbet, a stem passing through the spider with a nut on its lower end. The valve is reinforced with a ring-face of similar durable metal held by a clamp and nut; the ring may be reversed when worn.
Hollow clamping stem. A hollow fastening stem secures the valve-seat and receives a guide-stem for the lower end of the valve.
Claims: Four claims cover the rotary frame/weighted-lever fulcrum combination; the valve-seat with stem, spider, and nut; the face and guide secured by the same clamp; and the valve with guide-pin combined with the socketed valve-seat.
Source: https://patents.google.com/patent/[US139055](/patent/US139055)/en
What the excerpt does not establish: It does not identify an assignee, any ownership transfers, litigation, validity, or prior art beyond the inventor's own earlier patents (August 14, 1860; December 27, 1864; November 21, 1865), which are referenced but not supplied. It also does not provide the full text of cited references or drawings.
Generated 10/1/2026, 9:41:48 PM
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Litigation summary
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PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.