Chemical, microstructural, and mechanical property characterizations were performed on three continuous miner drive torque shafts for comparison purposes. Two of the shafts were fabricated from AISI-SAE 4140 steel (Shafts S & J) while Shaft X was fabricated from a non-standard medium carbon resulfurized free machining grade steel. All shafts were hardened and tempered. Variations were noted between the material chemistries, melt practice and heat treatments, with mechanical property results usable to calculate the torque values required for shear overload failure of each shaft. Shafts S and X were calculated to fail at lower torque loads than Shaft J.