摘要 |
An assembly includes first and second shafts and first and second sprockets. The first shaft has a first and second ends and a first longitudinal axis of rotation. The first sprocket is attached to the first shaft proximate the first end of the first shaft. The first sprocket rotates with the first shaft. The second shaft is spaced from the first shaft by a distance, the second shaft having a first end spaced from the first end of the first shaft by the distance, a second end spaced from the second end of the first shaft by the distance, and a second longitudinal axis of rotation substantially parallel to the first longitudinal axis of rotation. The second sprocket is attached to the second shaft proximate the second end of the second shaft. The second sprocket rotates with the second shaft. The distance is adjustable. |