Importance

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Abstract

An actuator for opening and closing a valve connected into a tubular element at the upper end of a drill string, to close off the flow of fluid through the element, and including a sleeve about the tubular element movable upwardly and downwardly relative thereto and mechanism carried by the sleeve for pivoting a valve actuating member to open and close the valve upon upward and downward movement of the sleeve. The specified mechanism preferably includes a part which interfits with the valve actuating member in a manner pivoting it upon upward and downward movement of the sleeve, but which desirably moves out of that interfitting relation in the extreme upper and lower positions of the sleeve to enable manual actuation of the valve in those positions without interference by the actuating mechanism. The apparatus also may be operable to yieldingly urge the pivoting valve actuating member as far as it can turn in the fully opened and fully closed positions of the valve in order to always assure complete opening or closing of the valve even when some of the parts may have become worn.

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First Claim