Abstract: A power transmission device for machine tools which provides tow driven shafts at a right angle to each other. A first driven shaft is disposed at a right angle to a driving shaft and is driven from a bevel gear on the end of the driving shaft engaging a ring or crown gear on the first driven shaft. A second driven shaft is disposed parallel to the driving shaft and carries a pulley driven from a pulley on the driving shaft. The driving shaft is adjustable toward and away from the second driven shaft to allow adjustment of the tension of a belt disposed around the pulleys, and the ring or crown gear is movable axially on the first driven shaft to allow such adjustment.