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:
Aug. 19, 1980
Filed:
Dec. 01, 1978
Narahari Gattu, Cedar Rapids, IA (US);
Paul E Johnson, Cedar Rapids, IA (US);
Harnischfeger Corporation, W. Milwaukee, WI (US);
Abstract
A telescopic boom comprises a base section, an inner section telescopable within the base section, an outer section telescopable within the inner section, and an actuator mechanism located within the outer section and operable to telescopically move the inner and outer sections relative to each other and to the base section. The actuator mechanism comprises an extendable and retractable elongated hydraulic cylinder or ram in the boom and comprising two relatively movable ram components, such as a cylinder housing and piston rod. One of the ram components (the piston rod) is connected to the base section and the other of the ram components (the cylinder housing) is connected to the inner section. An elongated cable support member is rigidly connected to the base section and extends into the boom. Means are provided to slideably support the first end of the hydraulic ram on the outer section and to slideably support the first end of the cable support member on the ram. First and second pulleys are mounted on the cylinder housing near opposite ends thereof, and first and second cables are reeved around the first and second pulleys, respectively. Each cable has one end anchored to the cable support member and the other end anchored to the outer section. The aforesaid other end of each cable is anchored to the outer boom section by an adjustable cable anchor assembly which is accessible from the exterior of the boom. Means are provided for extending and retracting the hydraulic ram to thereby cause the ram to telescopically move the inner section relative to said base section and to cause the pulley/cable system to telescopically move the outer section relative to the inner section.