Proper care and storage of spare gearboxes is critically important for insuring gearbox reliability. Industrial Outpost is here with a few methods to help you protect your spares until you need to break them out.
Method 1: Lip Seals
- Spray your shaft extensions with a suitable dry-film or preservative. A good example of such a product is Tectyl 846
- Pack grease around your oil seats to prevent cracking and drying
- Fill your gearbox casing completely with oil and be sure to seal it tightly. Label your gearbox as, "FULL - NOT READY FOR SERVICE"
- Allow some room for thermal expansion
- Remove your gearbox's breather and replace it with an airtight plug
This method is a simple and somewhat permanent solution for storage. However, it might not be cost-effective in larger gearboxes where more oil is required. There can also be a serious hazard if your gearbox accidentally springs a leak.
Method 2: Labyrinth Seals
- Spray your shaft extensions with a similar type product as described in Method 1
- For gearboxes with non-contact labyrinth seals, you should use an internal vapor-phase rust protective coating, rather than an oil fill like in Method 1. Both oil wet and non-oil wet surfaces are protected by vapor phase rust inhibitors
- Consider commercial vapor-phase rust inhibitors such as Tectyl 859A
This method will only serve its purpose for about 6 months. If your storage period is longer, you should look into renewing the method after that time. A disadvantage is that it may cause incompatibility and foaming problems when finally filled with the service oil that the gearbox calls for. Thorough flushing is recommended before putting the gearbox into operation.
Method 3: Oil Mist
- Oil mist introduces a clean air/oil mixture of 1 part oil to 200,000 parts of air into the gearbox -- keeping surfaces slightly lubricated and preventing corrosion
- This method is recommended for larger gearboxes and particularly when there are ten or more pieces of equipment being stored
Additives in the oil mist work to protect gear and bearings. Low pressure keeps out environmental contaminants such as dirt and moisture. It is the most safe, non-hazardous way to store spare gearboxes. One system can provide oil mist to multiple gearboxes as well. The main downsides are that this method could be expensive and difficult to implement.
Storage Maintenance Issues
- Rotate gearbox shafts at least once a month to distribute oil and prevent false corrosion
- When rotating exposed machinery surfaces, conduct a visual inspection to make sure that the applied protective coatings haven't been removed
- Storing equipment in environments where there is vibration can cause false brinelling and fretting corrosion
- If possible, store gearboxes in an environment where the temperature will be consistent