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Power transmission having a continuously variable gear ratio

  • US 4,345,486 A
  • Filed: 03/20/1979
  • Issued: 08/24/1982
  • Est. Priority Date: 03/22/1978
  • Status: Expired due to Term
First Claim
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1. A power transmission for transmitting power from a driving shaft to a driven shaft along a main axis of the transmission and having a continuously variable gear ratio, in which torque is transmitted by friction forces at points of tangency between balls and runways and wherein the balls and runways are divided into two axially spaced groups, the balls in each group rolling on four runways, two of which runways are rotationally immovable with respect to each other and two of which runways are coupled to the driving and the driven shaft, respectively, each group of runways including at least one radially inner runway and at least one radially outer runway, at least two of the runways in each group being axially displaceable, the two groups of balls being coupled in parallel, a respective radially inner runway of each group being connected to a respective radially inner runway of the other group to resist relative axial movement of said radially inner runways, and a respective radially outer runway of each group being connected to a respective, radially outer runway of the other group to resist relative axial movement of said radially outer runways, the cross-sectional shapes of the runways being determined by the equationswhere x and z are the relative axial displacements of the balls and the radially outer and inner runways, respectively, f is the gear ratio of the transmission, y and y1 are the corresponding variable radial distances of the ball centers from the main axis of the transmission, and u, u1, v and v1 are the angles between the ball radii to the

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