Patent ID: 8100790

Claim:
A conical disk pair for a belt-driven conical-pulley transmission, said conical disk pair comprising: a shaft that is rigidly connected to an axially fixed disk, an axially movable disk that is carried on the shaft so that it is axially movable along the shaft and is rotationally fixed thereto, a torque sensing device having a first shaped surface that is rigidly connected to the shaft, and having a second shaped surface that is rigidly connected to an annular sensing piston that surrounds the shaft and is axially movable along and rotatable relative to the shaft, which sensing piston is non-rotatably connected with and is axially movable relative to an input wheel, rolling elements positioned between the first and second shaped surfaces, the first and second shaped surfaces formed so that when an operative torque between the sensing piston and the movable disk changes, the axial position of the sensing piston along the shaft changes due to the rolling elements situated between the first and second shaped surfaces rolling along the first and second shaped surfaces, and so that the sensing piston increasingly closes an outflow opening formed in the shaft for fluid to flow out of a pressure chamber that bounds the sensing piston, and a recessed cylindrical guide surface formed on the shaft for axially guiding the sensing piston along the shaft and positioned radially opposite to and radially spaced from a corresponding opposed cylindrical surface formed on an inner surface of the sensing piston, wherein the cylindrical guide surface of the shaft includes a first, radially-outwardly-extending step and the opposed inner cylindrical surface of the sensing piston includes a second, radially-inwardly-extending step that axially faces and is axially opposed to and spaced from the first radially-extending step to define therebetween an annular damping chamber that contains fluid during operation of the transmission, wherein the annular damping chamber is bounded between the cylindrical guide surface of the shaft, the opposed cylindrical inner surface of the sensing piston, and the first and second axially-spaced and axially-opposed radial steps, and wherein the damping chamber has a volume that changes when the sensing piston is moved axially relative to the shaft for damping axial motion of the sensing piston relative to the shaft.