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:
Apr. 24, 1979
Filed:
Jan. 11, 1978
William L Shepherd, West University Place, TX (US);
Hughes Tool Company, Houston, TX (US);
Abstract
A device for applying an additional downward force to the rotating cutting tool of an earth boring machine. The machine has a mast and a rotating drive member suspended by the mast for vertical movement and for rotating the cutting tool. A rotatable drum is carried by hydraulic cylinders adjacent and below the top of the drive member. The drum has a brake and is connected by a downcrowding cable to the top of the drive member. Downward movement of the hydraulic cylinders while the drum brake is locked creates tension in the cable, applying downward force to the drive member. A take-up cable is wrapped around the drum in the opposite direction. It is reeved over the mast and connected to the top of the drive member by a spring. The spring takes up slack in the cable when the hydraulic cylinder returns for a new stroke and allows the kelly to move downward as the drum is pulled down by the cylinder.