In gravity roller conveyor applications, using open or steel shields can prevent increased friction in the bearings. Although the bearings can operate at temperatures up to 170°C, steel-shielded bearings should not be used above 100°C because the shields will deform. Special lubrication considerations are necessary outside the 0°C to 65°C range.
In high-temperature applications, the spacing between conveyor belt loads should be increased, and the belt should move quickly to reduce heat absorption by the rollers. A roller cooling system is also recommended. The load capacity of the rollers is determined by the bearing load capacity and the roller width. The basic bearing load capacity is determined by empirical formulas and experimental testing. This is rated for narrower conveyors; as the width increases, the roller load capacity decreases due to shaft deformation. The load capacity of gravity roller conveyors is highly dependent on the components used, and varies depending on the combination of motorized rollers, frame, and supports.
There are three assembly methods based on the processing shape: direct pressure type, coiled type, and formed type. The roller assembly on the frame track can be higher or lower than the frame, depending entirely on the application requirements. If the rollers are lower than the frame track, the frame track can be used as a guide rail, eliminating the need for separate safety rails; however, this is not suitable for wider loads due to interference with the frame. Conversely, having the rollers higher than the frame, with separate safety rails, offers greater flexibility in applications. The most common frame types are channel steel, L-shaped steel, or flat plate formed types. Based on the forming method, they can be divided into bent formed and structural steel types. Structural steel is heavier and stronger, used for heavy loads. Usually, the same type of steel is used on both sides of the conveyor, welded or bolted together with crossbeams. However, for some specific applications, the frame types on both sides may not be the same. More rollers provide better conveying performance and load capacity, and better tracking during turns.
Additionally, this type of structure also features modules designed with a three-ribbed, fishbone-like frame. Due to its self-centering tracking capability, it allows the load to move along the centerline of the conveyor.
