US Patent 7784565 Top drive systems with main shaft deflecting sensing

A top drive system for wellbore operations, the top drive system including motor apparatus, a main shaft driven by the motor apparatus, and sensing apparatus for sensing bending of the main shaft; and, in certain aspects, the system providing information regarding the extent of main shaft bending and/or for warning an operator of an undesirable amount of main shaft bending. This abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims, 37 C.F.R. 1.72(b).