The crank drive includes wheel crank gearing comprising a fixed internally cogged wheel (3) with a diameter the length of the piston stroke, and an externally cogged rotating wheel (4) rolling in same with a diameter the length of half the piston stroke. A crank pin (6) of the crank shaft (7) is set in the middle of the rotating wheel and the piston rod (10) is mounted on a bearing pin (9) at the side on the rolling circuit of this wheel so that a straight guide is provided for the piston rod. A compensating mass (21) is provided on the crank shaft opposite the crank pin and a further compensating mass (22) is provided on the rotating wheel opposite the bearing pin.
