Patent ID: 8517874

Claim:
A chainwheel assembly including a plurality of chainwheels engageable with a chain having successive alternating pairs of inner link plates and outer link plates connected by pins, the pins surrounded by rollers, the chainwheel assembly comprising: at least one smaller chainwheel having a plurality of teeth spaced about its circumference; and at least one larger chainwheel having a plurality of teeth spaced about its circumference, the larger chainwheel and the smaller chainwheel oriented relative to each other such that a distance between a center of the chain roller positioned between a pair of adjacent teeth on the larger chainwheel and the center of the chain roller between a pair of adjacent teeth on the smaller chainwheel is substantially an integer multiple of the chain pitch, at least a first tooth of the pair of adjacent teeth on the larger chainwheel including a first lateral recess disposed on a front face of the larger chainwheel facing the smaller chainwheel to allow the chain to move from the smaller chainwheel towards the larger chainwheel, the first lateral recess having a first run-on ramp configured to lift the outer link plate in a radial direction when the outer link plate is positioned laterally at the first tooth, at least a second tooth of the pair of adjacent teeth disposed adjacent to the first tooth opposite the drive rotation direction including a second recess disposed on the front face of the larger chainwheel facing the smaller chainwheel to allow the chain to move from the smaller chainwheel towards the larger chainwheel, the second recess having a second run-on ramp configured to lift the outer link plate in the radial direction when the outer link plate is positioned laterally at the second tooth, wherein the first recess is separate from the second recess.