4. How to Select Chains
Each manufacturer’s catalog shows the allowable roller load, according to each roller type and design. Check the appropriate catalogs. NOTE: The values listed for bearing roller chain and plastic roller chain are for unlubricated operation; the values for other types of chain are for lubricated conditions. On the standard A attachment, bending load occurs from the carried load. Twisting forces may also occur, depending on the direction of the load. The manufacturer’s catalog shows the allowable load for bending load. 4.3 SELECTION EXAMPLE Now that we’ve covered the procedures you need to follow to choose a conveyor chain, let’s complete an example. Your assignment: Select a suitable chain for the conditions shown in Figure 4.23. 1. Operating conditions (Figure 4.23). In addition, note the following: • The conveyed object is steel pipe supported on a plate. • The system operates in a clean environment. • The environment and conveyed objects are at ambient temperature. • The chain can be lubricated.
2. The chain conveyor type: loading on slat conveyor. 3. The chain type: check both RF and RF-B types.
4. The roller type: R-roller. 5. The chain pitch: 250 mm. 6. The number of sprocket teeth: based on the chain pitch and the
chain speed, select six teeth. 7. The attachment type: A-2. 8. Determine the chain size from the tension.
In this example, two sets of chain convey 80,000 kg. Therefore, each of the selected chains must be able to carry more than 40,000 kg per one set. Table 4.5 shows you that either RF17 (general series) or RF10-B are acceptable. NOTE: We are ignoring the dynamic tension of starting and stopping to make the example easier to understand. 9. The allowable roller load. Chain pitch is 250 mm and the length of the conveyed object is 1,000 mm. Object length/pitch = the number of rollers under the conveyed object. 1,000/250 = 4 rollers If we use two sets of chain, there are eight rollers under one conveyed object. If the steel pipes on the plate are not carried equally, uneven load occurs on the roller. In this process, we presume that only four rollers share the load. The roller’s load = (2,000 3 g ) / 4 = 4,900 N = 4.9 kN According to the catalog, either RF26 (standard series) or RF12-B (roller bear- ing) may be selected.
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