Power slip

Abstract

A power slip that utilizes modified SDXL slips and regular drilling bowls that fits to the pin drive master bushings of the rotary table and utilizes the depth of the drive pin holes as part of the actuators, thus allowing the power slip to set lower for added clearance and safety during drilling operations. Cables are anchored to a base plate and slip linkages and slip connectors are pivotally mounted to the slips and to the top plate so that, when the lift cylinders are actuated, the slips are moved to the released position. This two-stage linkage and cable design maximizes the movement of the slip assemblies while minimizing vertical movement of the power slip's housing. The base plate of the power slip is provided with a plurality of tubular pins adapted for mounting the base plate to the pin master bushing of a rotary table, and a portion of the lift cylinder is positioned in the interior hollow pins to maximize the movement of the slip assemblies upon actuation of the lift cylinders while minimizing the vertical dimension of the power slip.

1 . A power slip for releasably gripping a tubular comprising:
 a base plate;   a top plate;   one or more selectively actuated lift cylinders mounted between said base plate and said top plate for raising said top plate relative to said base plate; and   at least two slip assemblies, each of said slip assemblies comprising:
 a slip linkage pivotally mounted to said top plate; 
 a slip connector pivotally mounted to the slip linkage at one end and adapted at the other end for pivotally mounting to a slip segment for releasably gripping a tubular positioned between said slip assemblies; 
 a pulley mounted to said top plate; and 
 a cable having one end anchored to said base plate and the other end anchored to either the slip linkage or the slip connector, or to both the slip linkage and the slip connector, and passing over the pulley for pulling a slip segment up and back away from a tubular positioned between said slip assemblies when said top plate is raised relative to said base plate by actuating said lift cylinders. 
   
   
   
       2 - 12 . (canceled) 
   
   
       13 . A power slip for mounting to a pin drive master bushing comprising:
 a bottom plate;   a lift cylinder;   a top plate supported above said bottom plate on said lift cylinder;   a plurality of cables, each of said cables being anchored to said bottom plate and passing over a pulley mounted to said top plate;   a slip segment for releasably gripping a tubular, said slip segment being mounted to a respective cable for moving between first, set and second, raised positions as said top plate is raised and lowered relative to said bottom plate by selectively actuating said lift cylinder; and   said bottom plate being provided with a plurality of hollow pins for engaging a pin drive master bushing, one or more of said pins receiving said lift cylinder therein.   
   
   
       14 . The power slip of  claim 13  additionally comprising a tension cable for limiting movement of said top plate relative to said bottom plate when said lift cylinder is actuated. 
   
   
       15 . The power slip of  claim 13  additionally comprising a slip linkage pivotally mounted to said top plate and having said cable mounted thereto for pivoting said slip linkage relative to said top plate when said lift cylinder is actuated. 
   
   
       16 . The power slip of  claim 15  additionally comprising a slip connector interposed between said slip linkage and said slip segment for pivoting relative to said slip linkage when said lift cylinder is actuated, said slip segment being mounted to said slip connector. 
   
   
       17 . The power slip of  claim 16  wherein said slip connector includes an angled portion for providing rotation and mechanical advantage to the movement of said slip segment upon actuation of said lift cylinder.