Fisher-Price 'Rocky to the Rescue' part number is T5579. You can download the instruction sheet here.
I see no reason to suppose that it's motorised any different to the earlier Tomy version, i.e. the motor raises and lowers the crane jib, it does not drive the crane/wagon assembly along the track, though I'd be happy to be proved wrong. It looks like they just changed the design of the battery wagon. (and the 'Product Description' looks a bit screwy! though it suggests it may have been a Toys 'R Us exclusive).