Basics
more often if the chain is used in harsh environments. Why are inspections important? Over the life of a chain, the pins and bushings wear gradually. There may have been an unexpected shock load on the line, or a malfunction- ing oven might expose the chain to very hot conditions. During an inspection, make sure to check for the following conditions: • Cracks in the link plates (Figure 7.10). • Cracks in the rollers (Figure 7.11). • Rotated pins (Figure 7.12). • Wear on the end surfaces of link plates (Figure 7.13). If you find any of these conditions, take immediate steps to correct the problem. A quick checklist is included in Table 7.2. In addition, some trou- bleshooting tips are included in Section 7.1.6.
Table 7.2 Inspection Checklist
Procedure
Inspection
1. Visually check the chain during
In addition to the items to check during operation given in Section 7.1.3, also confirm that the lubrication conditions are suitable. (Look at both the method and
operation.
amount of lubrication.)
2. Stop the chain
1. Check the external cleanliness, corrosive, and lubrication conditions; also look for scratches or other damage to the link plate side and edge surfaces, pin edges,
and carefully
inspect each part of the chain and
and roller surfaces.
2. Inspect for pin rotation and the gap between the plate and the pins. 3. Inspect the sprocket teeth surfaces and teeth side surfaces for scratches or marks. 4. Measure the elongation of the chain due to wear. 5. Check the flex of the chain and the spin of the rollers. 6. When using a terminating device for lift applications, inspect the wear of the terminator and the wear of the pins. Also, check for proper installation.
sprocket.
Positions Where Cracks are Likely to Develop
Figure 7.10 Example of a Crack on a Link Plate Figure 7.11 Cracks on the Rollers
H
5% of H
Correct Position
Rotated Position
Figure 7.12 Rotation of the Pins
Figure 7.13 Wear on the End Surfaces of the Plates
7.1.6 Troubleshooting and Problem-Solving If you find something wrong with a chain during start-up or regular inspec- tion, it may require treatment or you may need to replace it with a new chain. A variety of problems and their solutions is shown in Figure 7.14.
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