Patent ID: 6949039

Claim:
A driven pulley for use on a main shaft defining a rotation axis, the driven pulley comprising: a first sheave having a first side and a second side, the first sheave comprising: a substantially annular and radially-extending main portion, the main portion having a conical wall provided on the first side of the first sheave; a substantially axially-extending bracket portion connected to the main portion and projecting from the second side of the first sheave, the bracket portion defining an internal enclosure opened at the first side of the first sheave; a sleeve portion connected to the bracket portion at a distal location with reference to the main portion; and at least two ramps symmetrically-disposed with reference to the rotation axis and directly connected to the first sheave inside the internal enclosure; a second sheave having a first side and a second side, the second sheave comprising: a substantially annular and radially-extending main portion, the main portion of the second sheave having a conical wall on the first side thereof, which conical wall faces the conical wall of the first sheave to form a belt-receiving groove between them; an outer sleeve portion axially projecting from the first side of the second sheave; an inner sleeve portion coaxially positioned inside the outer sleeve portion, the inner sleeve portion and outer sleeve portion defining between them an annular space with a substantially closed bottom; and at least two followers and corresponding mounting supports symmetrically disposed on the outer sleeve portion; and an axially-disposed helical spring having one end resting against the closed bottom of the annular space and an opposite end connected to a fixed location with reference to the first sheave; whereby, in use, the outer sleeve portion of the second sheave is housed in the internal enclosure of the first sheave and each follower is configured and disposed for being in engagement with a corresponding ramp, the sleeve portion of the first sheave being rigidly connected to the main shaft while the inner sleeve portion of the second sheave being free to rotate and slide with reference to the main shaft.