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US4280600A Expired / Lapsed US ⏱️ 0.0 years remaining

Self-refilling hydraulic actuator

Assignee: Otis Elevator Co
•
Filing: 1979-07-02
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Granted: 1981-07-28
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Expires: 1999-07-02
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Abstract

Abstract A piston slides in a fluid-filled piston chamber for damping or snubbing the movement of an object connected thereto. Attached to the piston is a piston rod which is disposed in the main fluid supply reservoir located below the piston chamber, at the lowest point in the apparatus. As the piston moves, the associated movement of this rod in the reservoir varies its displacement therein, thereby displacing fluid into a vented secondary reservoir which is located above the piston chamber, at the highest point in the damper apparatus. Any leakage from the piston chamber collects in the reservoirs. Both reservoirs are in fluid supply connection with the piston chamber so that piston movement causes fluid to flow into the chamber from the reservoirs so as to keep the chamber completely filled with fluid at all times. Both reservoirs supply fluid to the piston rod seals, which are thereby always immersed in fluid.

Inventors

  • 👤 John K. Salmon
  • 👤 Dwight Beazley

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-03 13:00
CPC Classifications
F; F16; F16F; F16F9/00; F16F9/32; F16F9/36; F16F9/10; F16F9/14; F16F9/16; F16F9/18; F16F9/20

Claims Analysis

Total Claims: 2
Claim 1
Independent Claim 132 words
A hydraulic cylinder characterized by: a piston; a piston rod attached to said piston; a fluid fillable cylinder having a first fluid supply reservoir at one end and a second fluid supply reservoir which is vented to ambient and located above said first reservoir, at a second, opposite end of the cylinder; said reservoirs being in fluid connection with each other, and said piston being slidably disposed in said cylinder, dividing it into two fluid fillable chambers; one of said chambers being in fluid connection with said second reservoir and the other of said chambers being in fluid connection with the first of said reservoirs; and said piston rod extending into said first reservoir for displacing fluid therefrom into the other of said reservoirs, as the piston moves towards said one end.
Claim 2
Dependent Claim 132 words
A hydraulic cylinder characterized by: a piston; a piston rod attached to said piston; a fluid fillable cylinder having a first fluid supply reservoir at one end and a second fluid supply reservoir which is vented to ambient and located above said first reservoir, at a second, opposite end of the cylinder; said reservoirs being in fluid connection with each other, and said piston being slidably disposed in said cylinder, dividing it into two fluid fillable chambers; one of said chambers being in fluid connection with said second reservoir and the other of said chambers being in fluid connection with the first of said reservoirs; and said piston rod extending into said first reservoir for displacing fluid therefrom into the other of said reservoirs, as the piston moves towards said one end.

References Cited (Backward Citations)

US404012A Cited
US2060590A Cited
US2849090A Cited
US3076643A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1984-07-27 1985-01-26 1985-07-28 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1988-07-27 1989-01-26 1989-07-28 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1992-07-27 1993-01-26 1993-07-28 $7700.00 Window Closed / Lapsed

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