Static structures (e.g. – buildings) – Mechanism operated relatively movable shaft assembly – Fluid pressure actuated
Patent
1977-07-08
1978-11-21
Murtagh, John E.
Static structures (e.g., buildings)
Mechanism operated relatively movable shaft assembly
Fluid pressure actuated
91530, 212 55, E02F 300, F15B 1120
Patent
active
041259742
ABSTRACT:
An electro-hydraulic control system to enable either simultaneous extension or retraction of all boom sections in a telescopic crane boom or independent extension or retraction of one or more individual boom sections comprises a valve assembly, including solenoid-operated extend and retract valves, on each boom section cylinder; a manually operable three-position (neutral, extend, retract) main control valve for connecting the valve assemblies to a pressurized fluid source and to a reservoir; a relay for energizing all solenoid valves simultaneously when the main control valve is operated to extend or retract positions to thereby effect simultaneous extension or retraction, respectively, of all boom sections; and manually actuatable selector switches, one for each movable boom section, which, when any one selector switch is actuated while the main valve is operated, override the relay and energize only the solenoid valves in a selected valve assembly thereby enabling independent extension or retraction of a selected boom section.
REFERENCES:
patent: 3721054 (1973-03-01), Hornagold
patent: 3777629 (1973-12-01), Johnston
patent: 3807108 (1974-04-01), Johnston
patent: 3809248 (1974-05-01), Ohniwa
patent: 3976098 (1976-08-01), Raymond
Fritsch Robert A.
Kay Christopher G.
Harnischfeger Corporation
Murtagh John E.
Nilles James E.
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