Roller turns are the most economical device, from the standpoint of first cost for providing radial support to overhead conveyor chain around a horizontal turn. Although they lack many advantages of traction wheels turns, they can perform a satisfactory job in most conveyor installations. Because of lower first cost, they are widely used.
Anchor roller turns are constructed with a separate mounting frame from which roller segments, segment support brackets and rail are supported. This sound construction method simplifies installation in addition to providing a rigid, well braced turn. The separate mounting frame enables the turn to withstand chain pulls far in excess of any that might be encountered in service. This unusual strength achieved produces an inherent safety factor not found in systems where the rail itself provides the backbone for the turn.
Anchor roller turns can be built to any required radius (12 or greater) and any degree of arc up to 180. Standard radii, which should be used whenever possible for economy reason, are 18, 24, 30, 36, 48 and 60. Standard turn arc are 30, 45, 60, 90, and 180. Larger radii and other turn arcs are available on special order.
When transporting large objects , which require support from two separate conveyor trolley assemblies, it is sometimes necessary to specify a large radius turn, such as a 14 radius. In such a case, it is usually more economical to break the turn into a series of smaller increments, such as several 18 radius turns at 15 arc, in sufficient number to accomplish the total desired turn.
Anchor roller turns are generally furnished with lubrication fittings in the roller pin. They also can be provided with lubrication-for-life rollers or with other special bearings if required.
On the overhead conveyor layout drawing, a length of straight rail equal to one trolley spacing should always be allowed between tangent points adjoining horizontal turns and vertical curves
In determining the proper size turn to employ, care must be taken to insure no interference between adjacent loads as they negotiate the turn.