US4549429A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of checking for hydraulic leakage
Assignee: Deere and Co
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Filing: 1983-12-02
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Granted: 1985-10-29
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Expires: 2003-12-02
Abstract
Abstract Leakage detection method for closed center hydraulic circuit wherein the existence of a leak within the circuit is indicated by changes in the RPM level of prime mover.
Inventors
- 👤 Lynn E. Kurt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:24
CPC Classifications
G; G01; G01M; G01M3/00; G01M3/02; G01M3/26; F; F15; F15B; F15B19/00; F15B20/00; F15B20/005; F15B2211/00; F15B2211/30; F15B2211/31; F15B2211/3105; F15B2211/3111; F15B2211/60; F15B2211/63; F15B2211/6303; F15B2211/633; F15B2211/70; F15B2211/705; F15B2211/7051; F15B2211/80; F15B2211/855
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
150 words
A method of detecting leakage in a closed center hydraulic circuit driven by a prime mover in driven feedback responsive communication with a variably displaceable pump unit, said hydraulic circuit including said pump unit, in fluid communication with a control valve for selectively directing hydraulic fluid to respective branches of said circuit, each branch having a fluid responsive displaceable work element, comprising the steps of: (a) positioning all said work elements in an extreme position; (b) placing said control valve in a neutral position; (c) locking out said feedback communication between said prime mover and said pump unit; (d) setting said prime mover to a reference RPM; (e) destroking said pump unit; and (f) comparing said change in prime mover RPM to a reference change in RPM whereby a change in RPM above a reference change in RPM indicates a leak in said circuit between said pump and control valve.
Claim 2
Independent Claim
150 words
A method of detecting leakage in a closed center hydraulic circuit driven by a prime mover in driven feedback responsive communication with a variably displaceable pump unit, said hydraulic circuit including said pump unit, in fluid communication with a control valve for selectively directing hydraulic fluid to respective branches of said circuit, each branch having a fluid responsive displaceable work element, comprising the steps of: (a) positioning all said work elements in an extreme position; (b) placing said control valve in a neutral position; (c) locking out said feedback communication between said prime mover and said pump unit; (d) setting said prime mover to a reference RPM; (e) destroking said pump unit; and (f) comparing said change in prime mover RPM to a reference change in RPM whereby a change in RPM above a reference change in RPM indicates a leak in said circuit between said pump and control valve.
Claim 3
Dependent Claim
97 words
A method as claimed in claim 1 further comprising the steps of: (a) returning said pump to stroke; (b) returning said prime mover to reference RPM; (c) placing said control valve to further position, said work element associated with a respective one of said branches in a said extreme position; (d) comparing said change in prime mover RPM to a reference change in prime mover RPM whereby a change in RPM above reference change in RPM indicates a leak in said circuit branch; and (e) repeating steps (c) and (d) for a difference one of said branches.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-10-28 | 1989-04-29 | 1989-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-28 | 1993-04-29 | 1993-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-28 | 1997-04-29 | 1997-10-29 | $7700.00 | Window Closed / Lapsed |