Abstract: A power transmission system for small vehicles or machinery having a principal forward speed and variable forward and reverse speeds capable of providing lower variable speeds is disclosed. The transmission system includes a primary transmission and a secondary transmission connected in series. In one of three positions, the two transmission housings and primary output shaft are keyed together. This results in a non-variable output, principal forward speed with a 1 to 1 ratio between the speed at which the engine rotates the primary transmission housing and the speed of the output shaft. In a second setting, the secondary transmission housing is keyed only to the output shaft from the primary transmission. This results in a forward speed having a variable output depending upon the load placed on the input shaft to the primary transmission. In a third position, the housings for the primary and secondary transmissions and the output shaft from the primary transmission are each disengaged from each other.