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:
Sep. 04, 1990
Filed:
Sep. 08, 1989
Jeffrey W Hamner, Allen, TX (US);
George P Schivley, Jr, Richardson, TX (US);
Ingersoll-Rand Company, Woodcliff Lake, NJ (US);
Abstract
A closed loop hydraulic system for use in a rotary drilling apparatus includes an extendible-retractable feed cylinder and a valve for biasing the feed cylinder. A variable, reversible displacement pump is provided for pumping fluid from either of the first and second pump ports, including pumping fluid to the feed cylinder. A reservoir retains a supply of fluid for the system. A check valve is provided for supplying additional fluid to the pump in response to the feed cylinder being extended. An overcenter valve is connected to each of the first and second ports for controlling flow from the system in response to pressures received from the first and second ports when the feed cylinder is extended and retracted.