Invalidity dossier
US 3722371
High ratio linkage mechanism
Current assignee: Pneumo Dynamics Corp
Added 9/23/2026, 4:39:53 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 3722371 A
Title: High Ratio Linkage Mechanism
Assignee: Pneumo Dynamics Corp (original assignee; also listed as current assignee)
Dates: Priority/filing date 1970-03-12; publication/grant date 1973-03-27; anticipated expiration listed 1990-03-27, status "Expired – Lifetime." (Google notes these as assumptions, not legal conclusions.)
Purpose: The patent describes a linkage mechanism for "accurately controlling movements of various fluid control systems, including servomechanisms, electrohydraulic valves and staged valves," and for high-ratio position equalizing, feedback, and position sensing.
Plain-language scope: Two or more elements are coupled by a drive member—one end fixed to an element, the other acting in an angled slot in the other element—to yield a high travel ratio. Motion combines rolling and axial movement translated through drive members in angled and helical slots. In the preferred form, an arm (with a ball) fixed to an output shaft rides in an angled slot on a drive piston, converting the piston's axial motion into shaft rotation; a second ball arm in an axially extending groove restrains the piston from rotating. A position-indicating device (e.g., a linear variable differential transducer) attaches directly to the piston so that, with only one joint between elements, position error is reduced. An auxiliary piston with a helical slot reacting against a fixed pin can drive axial-plus-rotational motion. Embodiments include two mechanisms sharing a common output shaft for position equalizing, and a version providing high-ratio position feedback from a fluid actuator to a single-stage valve via a jet pipe and torque motor.
Not established by this excerpt: The full claims, the complete description, the omitted text of FIG. 3, and any prior-art references or examiner citations. No statements are made here regarding validity, litigation, or ownership transfers, and none should be inferred.
Generated 10/1/2026, 9:44:19 PM
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Litigation summary
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PTAB challenges
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Assignment history
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Prior art
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Obviousness
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Extensions
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Derivative works
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