Patent ID: 8641576

Claim:
A hydraulic control arrangement for a variator having a pair of races, at least one roller which is arranged to engage both races to transfer drive from one race to the other and is movable in accordance with changes in variator drive ratio, a hydraulic traction loading actuator arranged to apply a traction load urging the roller and races into engagement to provide traction therebetween and so enable the transfer of drive, and at least one hydraulic roller actuator arranged to apply a reaction force to the roller, the hydraulic control arrangement comprising: hydraulics for applying fluid at an adjustable reaction pressure to the roller actuator to control the reaction force and for applying fluid to the traction loading actuator at a traction pressure which is related to the reaction pressure, thereby maintaining a relationship between reaction force and traction load; and a fluid component having at least two working chambers, at least one of which is selectively connectable to and disconnectable from one of the reaction pressure and the traction pressure, and at least one of which is supplied with the reaction pressure at any given time in operation, the traction force being dependent upon pressure in both of the working chambers, so that by connecting or disconnecting either or both of the working chambers to or from the relevant pressure, the relationship between reaction force and traction force is changed.