04529045 is referenced by 114 patents and cites 5 patents.

A top drive well drilling unit which is connected to the upper end of a drill string to drive it rotatively in drilling a well and is movable upwardly and downwardly with the string along a guide structure, and which is provided with pipe handling mechanism beneath the drilling unit for making and breaking a threaded connection between the drilling unit and the string and including an elevator which can suspend a section of drill pipe or the entire string when disconnected from the drilling unit. The pipe handling mechanism is retained against rotation with the drill string during a drilling operation, but is constructed to allow rotation of the elevator and a suspended string relative to the drilling unit when the string is supported by the elevator without connection to the drilling unit, in order to allow the string to rotate as it is moved vertically by the elevator and thereby avoid damage to the side wall of the well which may occur if a string having stabilizers is pulled upwardly without such rotation. Desirably, a powered torque wrench of the pipe mechanism is also free to rotate with the elevator during such vertical movement of the string, and is provided with control and power supply connections which need not be disconnected during the rotation.

Title
Top drive drilling unit with rotatable pipe support
Application Number
6/593313
Publication Number
4529045
Application Date
March 26, 1984
Publication Date
July 16, 1985
Inventor
Igor Krasnov
Fountain Valley
CA, US
George I Boyadjieff
Anaheim
CA, US
Agent
William P Green
Assignee
Varco International
CA, US
IPC
E21B 3/00
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