Abstract: A transmission assembly for providing an infinitely variable gearing between an input and take-off shaft, the gearing ratio achieved being dependent on the load applied to the take-off shaft. The assembly comprises a first gear mounted on the input shaft, a second gear mounted on the take-off shaft, a control gear rotatable, located between the first and second gears and a first gear train providing a driving connection between the first gear and control gear and a second gear train providing a driving connection between the control gear and the second gear, the gear train being rotatably mounted in a gear carrying member rotatably carried on the input and take-off shafts. The gear trains are arranged to induce opposing torques on to the control gear and the gear sizes are such as to provide a step down from the first gear to the control gear and a greater step up from the control gear to the second gear.