A snowmobile includes a track belt and a drive sprocket that couple with each other to propel the snowmobile with reduced noise and wear. The track belt has a plurality of driven projections and a plurality of driven windows at regular intervals along the direction of movement of the track belt. The drive sprocket has a projection drive portion and for engaging the driven projections and a window drive portion for engaging edges of the driven windows. In some embodiments, the driven projection, the driven window, the projection drive portion, and the window drive portion can be positioned so that the time when the driven projection and the projection drive portion contact each other is different from the time when the edge of the driven window and the window drive portion contact each other. Additionally, in some embodiments a damper is placed between the drive sprocket and the drive shaft. In some embodiments, a damper is coupled with at least a portion of a peripheral surface of at least one of the drive sprocket, the projection drive portion, and the window drive portion.