Patent ID: 6962543

Claim:
A variable ratio drive system ( 15 ) comprising: a first rotating member ( 20 ); a second rotating member ( 22 ); and a belt ( 24 ) connected between said first rotating member ( 20 ) and said second rotating member ( 22 ) and operable to transmit rotary motion therebetween, wherein at least one of said first and second rotating members ( 20 , 22 ) includes; a first sheave ( 42 ) and a second sheave ( 40 ), each rotatable about an axis (B), said sheaves ( 42 , 40 ) defining opposite conical surfaces ( 41 , 43 ) configured for frictional engagement with the belt ( 24 ); an adjustment mechanism ( 46 ) connected to said second sheave ( 40 ) and operable to move said second sheave ( 40 ) along said axis (B) relative to said first sheave ( 42 ), said mechanism ( 46 ) including; an adjustment shaft ( 154 ) having a threaded portion ( 156 ) extending from one end thereof; an adjustment motor ( 170 ) operably coupled to said adjustment shaft ( 154 ) and operable to rotate said adjustment shaft ( 154 ); a nut ( 158 ) defining a threaded bore ( 162 ) configured to threadedly receive said threaded portion ( 156 ) of said adjustment shaft ( 154 ) therethrough; said nut comprising a split nut having at least two separable portions ( 158 a-c ) that define said threaded bore ( 162 ) when said portions are combined; means for transmitting force between said adjustment shaft ( 154 ) and said second sheave ( 40 ) as said adjustment shaft ( 154 ) translates along said axis (B) while threading into said nut ( 158 ) and a second mechanism ( 48 ) for selectively combining and separating said portions ( 158 a-c ) of said split nut ( 158 ), whereby when said portions are combined said adjustment mechanism ( 46 ) is operable to move said second sheave ( 40 ) relative to said first sheave ( 42 ), and when said portions are separated said adjustment mechanism is inoperable to move said second sheave relative to said first sheave.