The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 05, 1977
Filed:
Jul. 07, 1975
Wilburn Kelly Brown, Morton Grove, IL (US);
Pettibone Corporation, Chicago, IL (US);
Abstract
Greater overall speed of crane operation is made possible by using a plurality of hydraulic piston-cylinder sets together with valving which can direct the pumped hydraulic fluid selectively to either of the cylinder sets or to both of them. Preferably the two cylinder sets are of different speed-load characteristics so that the same supply of pressured oil will raise the boom faster when supplied to one than when supplied to the other. When the boom must be raised with maximum load, the same oil supply will be directed to both cylinder sets, thereby giving the maximum lifting power with a given available oil pressure and the slowest raising speed. The overall time required to accomplish a given task is reduced because most of the time the boom can be raised or lowered at a faster speed than that slow speed which must be provided for handling heaviest loads. Speeds are selected by operating one or both of two handles to the up or down position, each handle controlling its own valve spool. When only one handle is moved to supply fluid under pressure, the other is moved to a 'float' position. Each valve spool must therefore have a float position, but for safety an interlock prevents moving both spools to the float position simultaneously.