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Single ball traction drive assembly

  • US 4,700,581 A
  • Filed: 11/18/1985
  • Issued: 10/20/1987
  • Est. Priority Date: 02/05/1982
  • Status: Expired due to Fees
First Claim
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1. In a variable drive transmission wherein a pair of independently rotatable input and output members are disposed in spaced facing relation to one another and a speed control mechanism therebetween to regulate the speed ratio between input and output members, said speed control mechanism comprising:

  • a single variable transmission element of generally spherical shape positioned between said input and output members, said transmission element being rotatable about a variable axis of rotation to impart the torque of said input member to said output member at a variable speed ratio, said input and output members being in the form of generally ring-like members having generally concave surfaces engageable with said transmission element on opposite sides of said transmission element, said output member having a bearing assembly provided with circumferentially spaced, rollable bearing elements between a pair of opposed races, one of said races defining one of said generally ring-like members including said concave surface and being journaled by said bearing elements with respect to the other of said races, internal confronting surfaces of said races having ramp members extending in a circumferential direction and angled inwardly toward said transmission element to cause the inward movement of said bearing elements along said ramp members whereby in response to increases in torque said bearing assembly means is operative to urge said one race against said transmission element and increase the pressure between said transmission element and said input and output members; and

    rotatable control roller means establishing surface engagement with said transmission element symmetrically about an imaginary radial line through the center of said transmission element which radial line bisects the angle formed between imaginary radial line extending from the center of said transmission element the points of engagement of said input and output members, said rotatable control roller means including means mounting said control roller means under predetermined compression to exert force against said transmission element in a direction causing said transmission element to bear against a limited surface portion of each of said input and output members, said rotatable control roller means being pivotal about said first imaginary radial line passing therethrough so as to establish an angle of surface engagement with said transmission element to vary the axis of rotation of said transmission element and thereby to vary the speed ratio of said input member to said output member through said transmission element.

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