Invalidity dossier
US 5657843
Press drive with oil shear clutch/brake drives
Current assignee: Midwest Brake Bond Co
Added 9/23/2026, 10:21:39 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 5,657,843
Title: Press drive with oil shear clutch/brake drives
Patent number: US5657843A
Application number: US08/523,279
Inventor: Gordon Maurice Sommer
Assignee: Midwest Brake Bond Co (original and current assignee as listed)
Priority/filing date: 1995-09-05
Publication (grant) date: 1997-08-19
Legal status (as listed): Expired – Fee Related; anticipated expiration 2015-09-05
Source: https://patents.google.com/patent/US5657843/en
Purpose
The patent addresses drawbacks of dry friction clutch/brakes in presses—wear of friction and reaction members, heat generation, periodic gap adjustment, and trip-rate limits tied to unit mass and inertia. It also addresses systems requiring complete separation of clutch and brake operation, which creates a "dead zone" that complicates emergency stopping requirements and press inching. The disclosed invention provides a single-speed press drive using an oil shear clutch unit and an oil shear brake, with controlled coordination (specified overlap) between their operations.
Plain-language scope
The clutch/brake unit (10) comprises a separate brake assembly (12) and clutch assembly (14) located on opposite sides of a flywheel, minimizing space required on any single side. Each assembly uses a multi-disk stack. The brake assembly includes a brake reaction hub, interleaved brake friction and reaction plates, a housing assembly, and a brake engagement assembly; the housing assembly and drive assembly define an oil chamber. A drive assembly (drive shaft, sun gear, planet gears, planetary carrier, ring gear) serves as the output. According to the description, separation of the units allows designed-in controlled overlap, and operation of both units and control of overlap is accomplished utilizing a single valve. Classification includes B30B15/10 (brakes specially adapted for presses) and various F16D disc-brake subclasses.
What the excerpt does not establish
The supplied text is explicitly an excerpt with omitted portions. It does not provide the full claims, the complete detailed description, all drawing details, or the full contents of the incorporated description. It does not establish validity, enforceability, litigation history, ownership transfers beyond the listed assignment, or prior-art effect. Statements about advantages and operation are as described in the patent text, not independent findings.
Generated 10/1/2026, 9:33:30 PM
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Litigation summary
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PTAB challenges
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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
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Obviousness
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Extensions
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Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.