Patent ID: 8607898

Claim:
A top drive assembly for a drilling rig having a derrick and a mover assembly, comprising: a power swivel including a drive motor and an output shaft extending downwardly from the drive motor; and a force compensator connected to the power swivel, the force compensator comprising: a carrier block having an upper side, a lower side, a first end, a second end, a first side, a second side, and a bore extending through the carrier block from the upper side to the lower side; a pair of top drive link assemblies positioned on either side of the power swivel and slidably positionable on a derrick of a drilling rig, each top drive link assembly having a lower end connected to the power swivel and an upper end connected to the carrier block in a way that the carrier block is positioned above the power swivel in a spaced apart relationship thereto; a mandrel slidably disposed through the bore of the carrier block, the mandrel having an upper end and a lower end, the upper end being connectable to the mover assembly of the drilling rig; and a shock absorber assembly interposed between the carrier block and the lower end of the mandrel in such a way that the shock absorber assembly is positioned in an expanded condition when a compressive force is applied to the power swivel and the mandrel and the shock absorber assembly is positioned in a compressed condition when a tensile force is applied to the power swivel and the mandrel.