Patent ID: 8381840

Claim:
A method of protecting a top drive drilling assembly, the method comprising the steps of: incorporating, in the top drive drilling assembly, a shock absorbing sub comprising a first body and a second body coupled to provide continual relative axial movement between an extended position and a retracted position during an earth drilling operation, with a shock absorbing fluid medium disposed between the first body and the second body to absorb any reactive axial force exerted upon the top drive drilling assembly, adapting the first body of the shock absorbing sub having a first coupling for coupling the shock absorbing sub with a thread form of a quill and the second body of the shock absorbing sub having a second coupling adapted to couple the shock absorbing sub with a drill string, and supplying the shock absorbing fluid medium through a fluid fill port on the first body connected to a supply unit capable of selectively increasing or decreasing the pressure of the shock absorbing fluid medium, located between the first body and the second body, to selectively increase or decrease dampening characteristics of the shock absorbing fluid medium to suit changing drilling conditions.