An IVT machine includes an input shaft, a drive wheel on the input shaft, an output shaft, a ratio changing device which is mounted on the output shaft, an endless belt which passes over the drive wheel and in an open loop on the ratio changing device, control elements for enlarging and reducing the belt loop dimension about the output shaft axis, belt guide elements providing a throat through which the belt enters and leaves its loop on the ratio changing device, and a drive arrangement on the ratio changing device for the transmission of drive power to the output shaft and is engaged with the belt in a portion of its loop on the device and engageable with the belt on both sides of the throat in its transition across the throat during rotation of the ratio changing device.