Straight full roller curves are acceptable for handling cylindrical packages rather than rectangular packages because of the lack of differential action on this type of roller. Since a package has a longer distance to travel in the area adjacent to the outer rail, a square or rectangular package will tend to bind at the outer rail, whereas a cylindrical package can roll against the outer ail and continue in the desired direction of travel.
Split roller and tapered curves provide the required increased outer speed or differential action permitting a square or rectangular package to the negotiate the curve, closely maintaining its original orientation. This type of gravity roller section should have straight gravity roller conveyors at the end of the infeed and at the discharge end of the turn, each equal to two-thirds the length of the package. This will enable the package to properly negotiate and remain centered in the turn.