Title: Crane with a pivoted boom and a float valve therefor

Abstract: A crane is disclosed having hydraulic means for boom elevation control which is provided with a load-holding check valve and a float valve interposed therebetween. The float valve is intentionally operable to a float position establishing fluid communication between opposed actuating chambers of the hydraulic means during crane transportation. The float valve includes a preferred position which does not interfere with conventional operation of combination of the hydraulic means and the load holding valve. The float valve is intentionally actuated to the float position by manually connecting a releasable coupling to a pilot pressure source. During crane operation, the releasable coupling is connected to a discharge hydraulic circuit that disables the float valve to prevent its inadvertent operation. The float valve is operable during crane transportation to allow the boom to move vertically in response to perturbations of a boom supporting dolly.

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Inventors: Livengood, Lynn W. (Chattanooga, TN, US)

Application Number: 694832
Filing Date: 1976-06-10
Publication_date: 1977-08-02
Assignee: Koehring Company (Milwaukee, WI)
Primary Class(es): 212/299 91/420, 91/464, 212/287
Other Classes:
US Patent Ref:

3083837	Apr, 1963	Jones et al.	212/46.
3426916	Feb, 1969	Novotny	212/46.
3613508	Oct, 1971	Krehbiel	91/420.
3908515	Sep, 1975	Johnson	91/464.
3924656	Dec, 1975	Hanser et al.	91/464.

Other Refs: 1,214,066

Apr, 1960	FR

Primary Examiner: Makay, Albert J.
Assistant Examiner: Johnson, R. B.
Attorney: Beck; Andrew J.