Patent ID: 6725946
Filing Date: 2004-04-27
Classification: E21B

Abstract:
An excavation apparatus comprising:kelly assembly means having an axis, a kelly assembly housing, an outer kelly section, and an extendable inner kelly section adaptable for attachment of a tool; kelly rotation means for rotating the kelly sections relative to the kelly assembly housing; support means for supporting the kelly rotation means and the kelly assembly means; frame means for allowing the kelly assembly housing to slide relative to the frame means in a direction parallel to the axis of the kelly assembly means; downcrowd means for downcrowding the support means relative to the frame means, the downcrowd means having a first end connected to and supported by the frame means, and a second end connected to and supporting the support means; and kelly deployment and retraction means for deploying the extendable inner kelly section out of the kelly assembly housing and for retracting the extendable inner kelly section back into the kelly assembly housing, the kelly deployment and retraction means having at least one kelly extension sheave supported directly by the frame means, and a cable having a first end attached to the extendable inner kelly section and a second end attached directly to either the support means or the frame means, the cable being looped under a kelly extension sheave of said at least one kelly extension sheave, whereby, the downcrowd means also serves as means for letting out and retracting the cable, thereby enabling the excavation apparatus to function without a winch for letting out and retracting the cable and without a reel for storing the retracted cable.