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:
Mar. 29, 1977
Filed:
Jan. 30, 1976
Theodore M Leigh, Cedar Rapids, IA (US);
FMC Corporation, San Jose, CA (US);
Abstract
A hydraulic jack, suitable for use as an outrigger support for a mobile crane, has a cylinder with a piston slidably received therein. Projecting from the piston is a rod that extends axially outward of the cylinder for supporting a load. The rod is externally threaded and a worm wheel nut is internally threaded to fit upon the rod. The nut is held in a fixed, axial position relative to the cylinder, and this nut must rotate on the rod to enable the rod to travel inwardly or outwardly of the cylinder. A rotatable worm is threaded to mesh with worm engaging gear teeth on the periphery of the worm wheel nut. Preferably, the thread on the worm has a helix angle with a self-locking characteristic, but the helix angle of the threads between the worm wheel nut and the piston rod is greater than the angle of friction so that there are no self-locking characteristics. The worm is driven by a hydraulic motor, that is connected with the cylinder in a hydraulic circuit, and a common control valve regulates the operation of both the cylinder and the motor.