Patent ID: 7313977

Claim:
An automatic, mechanical, continuously variable transmission ( 1 ) comprising an input shaft ( 2 ); a flywheel ( 10 ) connected to the input shaft; a drive assembly ( 5 ) including a drive pulley ( 6 ) defined by a first half-pulley ( 6 a ) and a second half-pulley ( 6 b ) which define a groove ( 8 ) of variable width for driving a belt (C); friction clutch means ( 12 ) interposed axially between said first half-pulley ( 6 a ) and said flywheel ( 10 ); a centrifugal actuating assembly ( 42 ) comprising a centrifugal actuating device ( 40 ) controlling said clutch means ( 12 ); said actuating device ( 40 ) including push means ( 54 , 61 ) for exerting an axial thrust on said first half-pulley ( 6 a ) through a force transmitting path not including the second half-pulley when an angular speed value of said input shaft ( 2 ) is greater than a first threshold value so as to connect said drive pulley ( 6 ) to said flywheel ( 10 ), and a speed regulating device ( 41 ) for moving said second half-pulley ( 6 b ) axially with respect to said first half-pulley ( 6 a ) to adjust the width of the groove ( 8 ) of the drive pulley ( 6 ) in response to speed variations of said input shaft ( 2 ), said speed regulating device ( 41 ) being active only when the angular speed value of said input shaft ( 2 ) is above a second threshold value; said second threshold value being higher than said first threshold value.