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:
May. 07, 2002
Filed:
Jul. 26, 2000
Raymond V. Nold, III, Round Rock, TX (US);
Schlumberger Technology Corporation, Sugar Land, TX (US);
Abstract
A hydrostatic transmission system for driving a rotatable member includes a differential having an output coupled with the rotatable member, a first hydrostatic drive having an output coupled to a first input of the differential, and a second hydrostatic drive having an output coupled to a second input of the differential. The output of the first hydrostatic drive is rotatable in a first selected direction and at a first selected speed. The output of the second hydrostatic drive is rotatable in a second selected direction and at a second selected speed. A rotational speed and direction of the output of the differential is related to the algebraic sum of the rotational speeds and directions of the outputs of the hydrostatic drives. In one embodiment, the speeds of the first and second drives are maintained above a minimum stable threshold, while operating the rotatable drive at very low or zero speed, by selecting the first direction to be opposite the second direction.