Centrifugal clutch shifter

A centrifugal clutch assembly and a device for use in combination with an engine, said clutch assembly comprising a shaft which carries a first sheave axially moveable on said shaft, a second sheave axially fixed on said shaft, a drive belt between said first sheave and said second sheave, a return spring operating on said axially moveable sheave, a roller fixed relative to said second sheave and a pivot pin fixed on and moveable with said first sheave;

• said device comprising:
• an elongated body pivotally coupled to said pivot pin and having first and second opposed ends and with an arcuate outer edge camming surface in contact with said roller so as to provide a camming motion to move said elongated body laterally relative to said roller;
• an aperture formed within said elongated body and disposed adjacent said first end thereof and constructed so as to mate with said pivot pin to allow said elongated body to pivot relative to said pivot pin for creation of said camming motion, the point of contact between said camming surface and said roller being determined by centrifugal forces operating on said elongated body and said pivot pin;
• a closed hollow chamber formed within and positioned internally of said elongated body with said hollow chamber having a chamber axis extending between said first and second opposed ends;
• and
• weighting means within said chamber and freely moveable reciprocably therein in response to centrifugal force from rotation of said shaft, wherein the relative position of the weighting means defines a counterweight ramp axis and with a counterweight ramp angle being the angle defined between the counterweight ramp axis and the direction of the centrifugal force, whereby in use, the movement of the weighting means within said chamber, thereby transferring a force to said first sheave to axially move said first sheave into engagement with said belt and with said belt engaging said second sheave to transfer rotation from said first sheave to said second sheave.

A device for use in a centrifugal clutch assembly, said clutch assembly comprising a shaft which carries a first sheave axially moveable on said shaft, a second sheave axially fixed on said shaft, a drive belt between said first sheave and said second sheave, a return spring operating on said axially moveable sheave, a roller fixed relative to said first sheave and a pivot pin fixed on and moveable with said first sheave, said device comprising:

• an elongated body having an arcuate outer surface constructed so as to provide a cam surface relative to said roller;
• an aperture formed within said elongated body and disposed adjacent said first end thereof and constructed so as to mate with said pivot pin to allow said elongated body to pivot relative to said pivot pin;
• a closed hollow chamber formed within and positioned internally of said elongated body, with said hollow chamber extending laterally from said first end toward said second end;
• weighting means freely moveable within said chamber, said weighting means comprising at least one generally spherical member having a predetermined mass, wherein the relative position of the weighting means defines a counterweight ramp axis and with a counterweight ramp angle being the angle defined between the counterweight ramp axis and the direction of the centrifugal force, whereby in use, the movement of the weighting means within said chamber alters the effective mass on the counterweight ramp angle, thus altering overall effective weight of the weighting means, so as to optimize positioning of said weighting means relative to said centrifugal force to controllably alter the centrifugal force effecting said elongated body;
• adjustment means for adjusting a first orientation of said weighting means within said chamber when said device is in said rest position, wherein in use, said first sheave rotates at a variable speed, so as to generate a centrifugal force upon said device whereupon at a predetermined engagement speed in the range of 4000 rpm to 6000 rpm, said device pivots from a rest position to a full engagement position as said weighting means move within said chamber thereby transferring a force to said first sheave to axially move said first sheave into engagement with said drive belt to transfer rotation to said second sheave.