Abstract: A variator assembly comprising a variator of the toroidal-race rolling-traction type. The assembly has input and output discs and rollers which are acted on by hydraulic roller control actuators. They are positioned between the discs to transmit torque from one disc to the other. Hydraulic end loading means 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. Reaction pressure supply means are connected to the roller control actuators to cause them to apply an adjustable reaction force to the rollers. The assembly also has hydraulically influenced valve means which serve to compare 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.

Abstract: A hydraulic control circuit is disclosed for a continuously variable transmission comprising a continuously variable ratio transmission unit (“variator”) 10, the circuit comprising a supply line 106 and means (which may take the form of a pump 110) for providing a flow of pressurised fluid in the supply line, means (which may comprise a pressure control valve 116) for generating a back pressure in the supply line, and at least one connection for feeding fluid from the supply line to a hydraulic actuator 100 acting on a movable torque transmission 23-37 element (which may comprise a roller 28) of the variator 10. The valve means 152 connected to the supply line allows pressure in the supply line to be selectively modified in response to rate of flow in the supply line.

Abstract: A continuously variable transmission is disclosed comprising a transmission input, a transmission output, and a continuously variable ratio unit (“variator”) arranged to be coupled between the transmission input (205) and output (240) by means of at least one clutch (230,250) thereby to enable transfer of drive between the input and the output at a continuously variable transmission ratio. The variator is connected to a hydraulic control circuit (50) and so subject to a hydraulic control pressure which is adjustable by the control circuit and is also influenced by changes in variator ratio. The variator is constructed and arranged such as to adjust its ratio to provide a variator reaction torque which corresponds to the control pressure. The transmission further comprising means (311,310) for adjusting the torque capacity of the clutch while it is engaged so that by controlling torque loading applied to the variator, the clutch influences the control pressure and the reaction torque.

Abstract: A hydraulic circuit for a continuously variable transmission having a continuously variable ratio unit that is controlled by at least one hydraulic actuator acting on a movable torque transmission element. The actuator has opposed first and second working chambers. The circuit includes first and second flow lines that are connected to two respective actuator working chambers. The lines feed fluid thereto and therefrom A pressurized supply of fluid urges fluid flow through the flow lines. A variable control valve is incorporated in both flow lines. Each valve generates an adjustable back pressure therein. A further valve is connected between the two flow lines. The further valve has a variable opening and is located upstream of the variable control valve. Opening of the further valve enables flow fluid from one flow line to the other to reduce pressure difference between the lines.

Abstract: A variator assembly is disclosed comprising a variator of the toroidal-race rolling-traction type 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 and hydraulic end loading means (200) 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. The assembly further comprises reaction pressure supply means connected to the roller control actuators to cause them to apply an adjustable reaction force to the rollers. In accordance with the invention hydraulically influenced valve means (204) are provided which respond to the reaction pressure and the end load pressure to control the end load pressure and thereby maintain a relationship between the end load and reaction pressures. Further adjustment means (350) to adjust the relationship between the end load and reaction pressures.

Abstract: A hydraulic control circuit is disclosed for a continuously variable transmission comprising a continuously variable ratio transmission unit (“variator”) 10, the circuit comprising a supply line 106 and means (which may take the form of a pump 110) for providing a flow of pressurised fluid in the supply line, means (which may comprise a pressure control valve 116) for generating a back pressure in the supply line, and at least one connection for feeding fluid from the supply line to a hydraulic actuator 100 acting on a movable torque transmission 23-37 element (which may comprise a roller 28) of the variator 10. The valve means 152 connected to the supply line allows pressure in the supply line to be selectively modified in response to rate of flow in the supply line.

Abstract: A hydraulic control circuit is disclosed for a continuously variable transmission having a continuously variable transmission unit (“variator”) in which the position of at least one ratio determining element (e.g. A roller 28 of a toroidal race rolling traction type variator) is influenced by means of a hydraulic actuator (100, 100′, 100″). The control circuit comprises a flow line (106) through which hydraulic fluid is fed to and from the actuator means (eg. A control valve 116 disposed in the flow line) for adjusting pressure in the flow line, and a first valve (125) connected to the flow line so that opening of the first valve diverts flow of fluid to/from the flow line.