6. Large Pitch Conveyor Chains
This is based on a phenomenon used in a basic science experiment; when you put sand in a long cylinder, closed at one end with paper, and push the sand with all your strength, the paper cannot be broken if the cylinder is long enough. This is because the friction between the sand and the cylinder absorbs all of the pushing force. Conversely, in the flow conveyor, the attach- ments work as moving walls, and the sand moves along with it. To lift con- veyed objects, the friction at the bottom wall of the conveyor must support the weight of the vertical portion, therefore, the conveyor must have a bottom line “L” shape. Because there is very little relative movement among the conveyed materials in this application, breakage is rare. The case width is determined by the attachment dimensions; usually it is less than 750 mm. Chains for flow conveyors include: RF03075 (average tensile strength, 29 kN) through RF26200 (314 kN) for grain conveyance; RF450W (108 kN) through RF36300N (868 kN) for other applications. Sprockets Standard sprockets for RF-type conveyor chain are used for flow conveyors. Detachable tooth sprockets are beginning to be used these days. Selection and Handling (1) There are several types of attachments available, depending on design and arrangement of the conveyor and whether material is pushed against the bottom of the casing or its side walls. Figure 6.14 shows several types of attachments (L, B, U 2 V, and W). The set-up on the right-hand side has more pushing power than the one on the left-hand side. The specific properties of the material conveyed determine the type of attachments that should be used. Discuss your application with the manufacturer.
L
B
U 2 V
W
Figure 6.14 Examples of Attachments for Flow Conveyor Chain
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