A belt-driven conical-pulley transmission having a shaft on the input end and a shaft on the power output end. One of the shafts includes at least one axial bore extending in the longitudinal direction of the shaft, and a transverse bore extending from the axial bore to an outlet on the surface of the shaft. A conical disk pair is carried on the shaft and includes an axially fixed disk and an axially movable disk. The axially movable disk includes internal teeth that engage with external teeth on the shaft, and it overlies the transverse bore outlet over its entire axial travel distance. The transverse bore outlet is positioned in the region of the interengaging teeth.