3766991 is referenced by 110 patents and cites 9 patents.

An electric power swivel for rotating and handling drill pipe during well drilling, adapted for use with either conventional drill pipe or larger diameter casing strings and having fluid pressure cushioned suspension means to accommodate vertical movements required in making up and breaking out threaded connections between pipe sections.

Title
Electric power swivel and system for use in rotary well drilling
Application Number
05/130,597
Publication Number
3766991
Application Date
April 2, 1971
Publication Date
October 23, 1973
Inventor
Brown Cicero C
IPC
E21b 19/16
E21B 03/00
E21B 19/20
E21B 19/00
E21B 03/02
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