Belt drive mechanism

Drive mechanism comprising:

• a frame (10) equipped with a body (16) containing at least one inner bearing race (24) defining a geometrical axis of rotation (26);
• a single-piece drum (48) located entirely on one side of a geometrical plane of reference (34) perpendicular to the geometrical axis of rotation and equipped:
• with a tread (50) that can cooperate with a drive belt,
• with an opening in which the body is inserted, and
• with at least one outer bearing race (54) located opposite the inner bearing race (24),
• rolling bodies (56) disposed on the bearing races to form a bearing (22);
• a shaft (30, 130, 430, 530) passing through the body and solidly attached to a turning element extending on a second side of the geometrical plane of reference;
• and
• means (40, 140, 440, 540) for linking the shaft to the drum, extending radially between the shaft and the drum, and tangential to a geometrical plane (62) which is perpendicular to the axis of rotation (26) and located at a greater distance from the transversal plane of reference than the bearing races.