US3657969A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic control system for extensible crane
Assignee: Case LLC
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Filing: 1970-07-10
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Granted: 1972-04-25
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Expires: 1990-07-10
Abstract
Abstract A hydraulic control system for producing synchronized extension and retraction of at least three crane sections which includes a first cylinder and piston rod assembly with the cylinder being attached to an intermediate section of the crane and the piston rod connected to a first or fixed crane section. A second cylinder is connected to the intermediate section and its piston rod is attached to a third section with a fluid divider supported on the second section and having first and second outlet ports, respectively, connected to one end of each of the cylinders and an inlet port. A first flow passage means extends through the first cylinder and piston rod assembly and is connected to the inlet port of the flow divider with a second flow passage means extending through the first piston rod and communicating with the opposite end of the first and second cylinders so that a pressured fluid source connected to one flow passage and a reservoir connected to the other flow passage means will extend the assemblies and the crane sections with the flow divider means producing synchronized movement of the crane sections. The control circuit further includes means for blocking flow from one end of each of the cylinders when the pressured fluid in the first fluid passage means is below a predetermined level. In addition, the flow divider means includes pressure responsive check valves providing unidirectional flow in opposite directions between the two outlet ports so as to interconnect the two ports when the pressure in either of the outlet ports exceeds a predetermined level.
Inventors
- 👤 Joseph P Wirkus
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:20
CPC Classifications
F; F15; F15B; F15B11/00; F15B11/16; F15B11/20; B; B66; B66C; B66C23/00; B66C23/62; B66C23/64; B66C23/70; B66C23/701; B66C23/705
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
218 words
In a crane having at least three extensible and retractable boom sections with a first boom section attached to a support, a hydraulic control system for extending and retracting said sections comprising a first cylinder and piston rod assembly, with said cylinder attached to a second section and said piston rod connected to said first section; a second cylinder and piston rod assembly having its cylinder attached to said second section and its piston rod attached to a third section; flow divider means on said second section, said flow divider means having an inlet port, a first outlet port connected to one end of said first cylinder and a second outlet port connected to one end of said second cylinder; conduit means interconnecting the opposite ends of said cylinders; first flow passage means extending through said first cylinder and piston rod assembly and connected to said inlet port; second flow passage means extending through said first piston rod and connected to said opposite ends of said cylinders; and means connecting a pressured fluid source and a reservoir to said first and second flow passage means to extend and retract said assemblies and said sections; said flow divider means dividing the fluid received in said inlet port equally to said cylinders to produce synchronized movement of said boom sections.
Claim 2
Dependent Claim
218 words
In a crane having at least three extensible and retractable boom sections with a first boom section attached to a support, a hydraulic control system for extending and retracting said sections comprising a first cylinder and piston rod assembly, with said cylinder attached to a second section and said piston rod connected to said first section; a second cylinder and piston rod assembly having its cylinder attached to said second section and its piston rod attached to a third section; flow divider means on said second section, said flow divider means having an inlet port, a first outlet port connected to one end of said first cylinder and a second outlet port connected to one end of said second cylinder; conduit means interconnecting the opposite ends of said cylinders; first flow passage means extending through said first cylinder and piston rod assembly and connected to said inlet port; second flow passage means extending through said first piston rod and connected to said opposite ends of said cylinders; and means connecting a pressured fluid source and a reservoir to said first and second flow passage means to extend and retract said assemblies and said sections; said flow divider means dividing the fluid received in said inlet port equally to said cylinders to produce synchronized movement of said boom sections.
Claim 3
Dependent Claim
71 words
A crane as deFined in claim 1, including the further improvement of first and second pressure responsive, unidirectional valve means between said one end of said cylinders and said first flow passage means, said valve means being responsive to the pressure of fluid in said second passage means to prevent flow of fluid from said cylinders when the pressure of fluid in said first passage means is below a predetermined level.
Claim 4
Dependent Claim
64 words
A crane as defined in claim 1, including the further improvement of first and second pressure responsive relief valve means in said flow divider valve, said valve means respectively providing unidirectional flow in opposite directions between said outlet ports and interconnecting said outlets when either of said assemblies is restrained whereby to maintain said assemblies synchronized at the maximum position of extension or retraction.
Claim 5
Dependent Claim
231 words
In combination with a crane including a boom having three sections with a first of said sections being attached to a support, a hydraulic control system comprising a source of fluid under pressure; a reservoir; first and second fluid rams each having first and second extensible and retractable elements, said first fluid ram having its first element connected to said first section and its second element connected to said second section, said second fluid ram having its second element connected to said second section and its first element connected to said third section; a flow divider valve on said second section having an inlet port and first and second outlet ports; a first conduit connecting said first outlet port to one end of said second element of said first fluid ram; a second conduit connecting said second outlet port to one end of said second element of said second fluid ram; a third conduit interconnecting the opposite ends of said second elements; first fluid passage means extending through said first fluid ram and connected to said inlet port; second fluid passage means extending through said first fluid ram and communicating with said opposite end of said second element of said first fluid ram; and valve means for connecting said source and said reservoir to said fluid passage means to extend and retract said rams causing extension and retraction of said sections.
Claim 6
Dependent Claim
231 words
In combination with a crane including a boom having three sections with a first of said sections being attached to a support, a hydraulic control system comprising a source of fluid under pressure; a reservoir; first and second fluid rams each having first and second extensible and retractable elements, said first fluid ram having its first element connected to said first section and its second element connected to said second section, said second fluid ram having its second element connected to said second section and its first element connected to said third section; a flow divider valve on said second section having an inlet port and first and second outlet ports; a first conduit connecting said first outlet port to one end of said second element of said first fluid ram; a second conduit connecting said second outlet port to one end of said second element of said second fluid ram; a third conduit interconnecting the opposite ends of said second elements; first fluid passage means extending through said first fluid ram and connected to said inlet port; second fluid passage means extending through said first fluid ram and communicating with said opposite end of said second element of said first fluid ram; and valve means for connecting said source and said reservoir to said fluid passage means to extend and retract said rams causing extension and retraction of said sections.
Claim 7
Dependent Claim
54 words
The combination as defined in claim 4, including the further improvement of first and second relief valves, respectively, providing unidirectional flow in opposite directions between said first and second conduits when the pressure in either of said first and second conduits exceeds a predetermined level to provide flow to the other of said conduits.
Claim 8
Dependent Claim
63 words
The combination as defined in claim 5, including the further improvement of first safety means in said first flow passage for blocking flow when the pressure of fluid in said second fluid passage is below a predetermined level and second safety means in said second conduit for blocking flow when the pressure of fluid in said third conduit is below a predetermined level.
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) | 1975-04-25 | 1975-10-25 | 1976-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-25 | 1979-10-25 | 1980-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-25 | 1983-10-25 | 1984-04-25 | $7700.00 | Window Closed / Lapsed |