Patent ID: 7318786

Claim:
A variator assembly comprising a toroidal-race rolling-traction variator having input and output discs, rollers which are acted on by hydraulic roller control actuators and are positioned between the discs to transmit torque from one disc to the other, a hydraulic end loading device supplied with fluid at an end load pressure to apply an end load to bias the discs and the rollers toward each other, thereby enabling the transmission of torque, and a reaction pressure supply connected to the roller control actuators to cause them to apply an adjustable reaction force to the rollers, the assembly further comprising a hydraulically influenced valve arrangement which serves to make a comparison of an input related to the end load pressure with an input related to the reaction pressure and to control the end load pressure in dependence upon the comparison, thereby maintaining a relationship between the end load and reaction pressures, and an adjustment device which serves to adjust a signal applied to the valve arrangement and thereby to adjust the relationship between the end load and reaction pressures, the adjustment device being controlled by an electronic controller in response to measured operating parameters.