US3920096A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vertical hydraulic ram system for scissors assembly scaffold
Assignee: W R CARPENTER HOLDING PTY Ltd
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Filing: 1974-07-01
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Granted: 1975-11-18
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Expires: 1994-07-01
Abstract
Abstract A scaffold having a base frame and a platform mounted on a vertically extensible and contractable scissors assembly, the scissors assembly comprising a plurality of ascending and interconnected scissors stages, each stage having spaced-apart pairs of elongated scissors elements pivotally connected at their midpoints. Two spaced-apart hydraulic lift cylinders extending vertically within the scissors assembly from the bottom of the base frame to the bottom of the platform when contracted are connected to frame and lowermost scissors stage to act vertically thereon and cause full upward extension of the platform. A third vertical hydraulic ram disposed centrally of the base frame acts upwardly directly on the platform to aid in the initial elevation of the platform and extension of the scissors stages.
Inventors
- 👤 Robert E Fisher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:16
CPC Classifications
B; B66; B66F; B66F11/00; B66F11/04; B66F11/042; E; E04; E04G; E04G1/00; E04G1/18; E04G1/22
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
244 words
An elevating scaffold comprising: a. a generally rectangular frame having an upper surface and lower central support members suspended a substantial distance below said upper surface, b. a plurality of ground-engaging wheels mounted on said frame, the bottom surfaces of said wheels being a relatively small distance below said lower central support members, c. an upwardly extensible and downwardly contractable scissors assembly mounted on the upper surface of said frame, said scissors assembly comprising a plurality of pivotally interconnected ascending scissors stages, the lowermost of which is connected to said frame, each stage comprising laterally spaced-apart pairs of rigid elongated scissors elements pivotally connected together at their midpoints, d. a work platform supported in and connected to the uppermost scissors stage, e. a first yoke connected to the midpoint of one of said pairs of scissors elements of said lowermost scissors stage and a second yoke connected to the midpoint of the other of said pairs of scissors elements of said lowermost scissors stage, said yokes extending upwardly substantially to the underneath of said platform when said scissors assembly has been fully contracted, f. a pair of laterally spaced-apart, hydraulically extensible rams, one for each yoke, the lower ends of said rams being pivotally secured to said lower central support members and the upper ends of the rams being secured to the upper ends of said yokes, g. means for forcing hydraulic fluid simultaneously into and for relieving hydraulic fluid simultaneously from said rams.
Claim 2
Dependent Claim
244 words
An elevating scaffold comprising: a. a generally rectangular frame having an upper surface and lower central support members suspended a substantial distance below said upper surface, b. a plurality of ground-engaging wheels mounted on said frame, the bottom surfaces of said wheels being a relatively small distance below said lower central support members, c. an upwardly extensible and downwardly contractable scissors assembly mounted on the upper surface of said frame, said scissors assembly comprising a plurality of pivotally interconnected ascending scissors stages, the lowermost of which is connected to said frame, each stage comprising laterally spaced-apart pairs of rigid elongated scissors elements pivotally connected together at their midpoints, d. a work platform supported in and connected to the uppermost scissors stage, e. a first yoke connected to the midpoint of one of said pairs of scissors elements of said lowermost scissors stage and a second yoke connected to the midpoint of the other of said pairs of scissors elements of said lowermost scissors stage, said yokes extending upwardly substantially to the underneath of said platform when said scissors assembly has been fully contracted, f. a pair of laterally spaced-apart, hydraulically extensible rams, one for each yoke, the lower ends of said rams being pivotally secured to said lower central support members and the upper ends of the rams being secured to the upper ends of said yokes, g. means for forcing hydraulic fluid simultaneously into and for relieving hydraulic fluid simultaneously from said rams.
Claim 3
Dependent Claim
31 words
Apparatus as set forth in claim 1 wherein the bodies of said rams are connected to said yokes and the pistons of said rams are connected to said central support Members.
Claim 4
Dependent Claim
124 words
Apparatus as set forth in claim 1, and wherein said scissors stages are pivotally connected together so that the scissors elements thereof are in parallelism when said scissors assembly has been fully contracted, and further including: h. a third hydraulically extensible ram, said ram being vertically disposed with its lower end supported on said lower central support members and its upper end engageablle with the bottom of said platform centrally thereof, the height of said third ram when fully contracted being substantially equal to the vertical distance from said lower central support members to the bottom of said platform when said scissors assembly is fully contracted, and wherein said means (g) additionally forces hydraulic fluid into and relieves hydraualic fluid from said third ram.
Claim 5
Dependent Claim
147 words
Apparatus as set forth in claim 3, wherein said means (g) comprises: a hydraulic fluid sump mounted on said frame, a hydraulic pump having its inlet in fluid communication with said sump, an electric motor drivingly connected to said pump, a plurality of batteries electrically connectable to and disconnectible from said motor, said batteries being supported by said frame at a low level above the ground and near each of said wheels, conduit means connecting the output of said pump to each of said three rams and for connecting each of said three rams to said sump, first valve means in said conduit means for opening and closing said conduit means for flow of hydraulic fluid from said pump to said rams, second valve means in said conduit means for opening and closing said conduit means for flow of hydraulic fluid from said rams to said sump.
Claim 6
Dependent Claim
32 words
Apparatus as set forth in claim 4, wherein said means (g) further includes check valve means in said conduit means for preventing flow of hydraulic fluid between said first and second rams.
Claim 7
Dependent Claim
33 words
Apparatus as set forth in claim 4, wherein said means (g) further includes constant flow devices in said conduit means in the path of hydraulic fluid flowing from said rams to said sump.
Claim 8
Dependent Claim
48 words
Apparatus as set forth in claim 6, wherein said means (g) further includes control means for selectively opening, one at a time, one or the other of said first and second valve means, and for electrically connecting said batteries to said motor when said first valve is open.
Claim 9
Dependent Claim
32 words
Apparatus as set forth in claim 7, wherein said means (g) further includes check valve means in said conduit means for preventing flow of hydraulic fluid between said first and second rams.
Claim 10
Dependent Claim
32 words
Apparatus as set forth in claim 4 wherein said means (g) further includes means for limiting the pressure of hydraulic fluid applied through said conduit means from said pump to said rams.
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) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |