Transmissions and drive systems for a self-propelled machine and related methods are provided. An input shaft having an axis and extending transverse to an output shaft is provided. The input shaft can be rotatable about the axis of the input shaft and configured to drivingly engage the output shaft. A variable pitch pulley can be disposed axially on the input shaft and configured to rotate about the axis of the input shaft. The variable pitch pulley can be configured to change pitch diameter to regulate the speed at which the input shaft is rotated. Further, the input shaft can be at least partially rotatable about an axis of the output shaft to vary the pitch of the variable pitch pulley to regulate the speed at which the input shaft drives the output shaft.