Abstract: A steplessly variable ratio transmission unit with swingable rollers (11, 12) interconnecting input and output toroidal discs (1, 2, 10), the swing of the rollers (11, 12) being controlled by a ratio actuator (146, 148) supplied by a pump (174) at a pressure controlled by a ratio valve (186). At an end of the stroke of the ratio actuator an end-stop valve (150) is actuated to constrict the flow to the ratio valve (186), and the raised pressure up-stream of a constriction (140, 142) in valve 150 acts on a piston (140) of that valve urging the ratio actuator (146, 148) away from the end of its stroke so that the rollers (11, 12) cannot run off the discs (1, 2, 10). A complete transmission system provides a First Regime with recirculation in planetary gearing and a Second Regime with drive through the transmission unit alone. In First Regime, at the lowest transmission unit ratio, that ratio and the overall system ratio are the same.