US4365429A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Maximum lift system for hydraulic hoe
Assignee: Terex USA LLC
•
Filing: 1981-11-18
•
Granted: 1982-12-28
•
Expires: 2001-11-18
Abstract
Abstract A maximum lift system for a hydraulic hoe includes a dual pressure relief valve in the hoist circuit and an actuating valve that delivers a signal to the relief valve to increase hoist capacity and simultaneously causes operation of lockout valves to center the wrist control valve and thus lock the dipper in position.
Inventors
- 👤 Frank A. Ecker
- 👤 Theodore G. Jensen
- 👤 Norman B. Christensen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 06:16
CPC Classifications
E; E02; E02F; E02F9/00; E02F9/20; E02F9/22; E02F9/2278; E02F9/2296; E02F9/2203; E02F9/2221; E02F9/2239; E02F9/2292; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/86493; Y10T137/86574; Y10T137/86582; Y10T137/86606; Y10T137/87169; Y10T137/87193
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
113 words
In a maximum lift system for a hydraulic hoe having a hydraulic hoist cylinder and associated hoist circuit, a double-acting hydraulic wrist cylinder with an associated wrist circuit, a dual pressure relief valve in the hoist circuit that has a normal lower operating setting and can be hydraulically biased to a higher maximum setting, and actuating means to supply a bias signal to the relief valve, the improvement wherein: there is a lockout means in the wrist circuit that is selectively operable to block the wrist circuit and lock the wrist cylinder in whatever position it is then in; and the actuating means operates the lockout means simultaneously with supplying the bias signal.
Claim 2
Dependent Claim
113 words
In a maximum lift system for a hydraulic hoe having a hydraulic hoist cylinder and associated hoist circuit, a double-acting hydraulic wrist cylinder with an associated wrist circuit, a dual pressure relief valve in the hoist circuit that has a normal lower operating setting and can be hydraulically biased to a higher maximum setting, and actuating means to supply a bias signal to the relief valve, the improvement wherein: there is a lockout means in the wrist circuit that is selectively operable to block the wrist circuit and lock the wrist cylinder in whatever position it is then in; and the actuating means operates the lockout means simultaneously with supplying the bias signal.
Claim 3
Dependent Claim
56 words
The system of claim 1, and in which the wrist circuit includes a three-position pilot operated valve with wrist control lines leading to opposite sides thereof, wherein: the lockout means comprises two lockout valves, one in each wrist control line, each lockout valve being normally open, the actuating means serving to simultaneously close both lockout valves.
Claim 4
Dependent Claim
84 words
The system of claim 2, and in which there is a three-position pilot operated control valve for the hoist cylinder, manual controls for the hoist and wrist valves, and a hydraulic control circuit for both the hoist and wrist valves, wherein: the lockout valves are hydraulically pilotable to closed positions; and the actuating valve is a normally closed valve connected to the control circuit that, when opened, simultaneously delivers the bias signal to the relief valve and pilots the lockout valves to closed positions.
Claim 5
Dependent Claim
34 words
A system according to claim 3, and in which there is a main pump with a main fluid line leading to the hoist valve, wherein: the relief valve is in said main fluid line.
References Cited (Backward Citations)
CA885292A
Cited
US2969844A
Cited
US3324881A
Cited
US3584751A
Cited
US3583585A
Cited
US3606049A
Cited
US3874532A
Cited
US3883023A
Cited
US3927603A
Cited
GB1403046A
Cited
US3865013A
Cited
US3934742A
Cited
US3922745A
Cited
US4044610A
Cited
US4218837A
Cited
US4288196A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-12-27 | 1986-06-28 | 1986-12-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-12-27 | 1990-06-28 | 1990-12-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-12-27 | 1994-06-28 | 1994-12-28 | $7700.00 | Window Closed / Lapsed |