A drive mechanism for a subterranean boring machine includes a drive motor, primary and secondary drive wheels, a drive sprocket and an idler sprocket attached to the primary and secondary drive wheels, respectively, and a chain operatively extending between the drive sprocket and the idler sprocket. The drive mechanism is movably mounted on the sled of a subterranean boring machine that rolls along a track, the drive mechanism being biased against the track by a set of springs to cause the prim...