We have been noting some interesting lubrication findings on gearboxes of 400-500 hp drives. These findings are especially relevant on installations where service factor limits are being stretched. Here are the findings:
A number of manufacturers will tell you that a loss of a single liter of oil within a gearbox will result in starvation to the input shaft bearing. This is ever worry-some as the input bearing is typically fastest revolving and requires a consistent application of lubricant. Most gearing is also located at the same level and it doesn't take much for the loss to equal 1 liter. Dip stick and sight glass Hi-Lo marking are often very tight to ensure an accurate representation of the oil inside.
Most manufacturers will recommend only taking oil level checks after their gearboxes have been down for a period of time. Unfortunately, this is not realistic in today's high production industrial environments.
Often gearbox levels are not respected during installation which results in readings being inaccurate.
For our "on the run" MAINTelligence Android/iOS inspections, we check daily gearbox temperatures and oil leaks on critical assets. A sample of what this can look like is below:
When an oil leak is selected on the list above, the app is programmed to activate a pop-up on the screen with an instruction for the inspector to take a picture. However, if no alarms are triggered, the inspection continues on as normal.
Any critical alarm triggered will result in the appropriate work request being created. In the case of an oil leak, a request for oil level measurement during the next outing will be created. The additional benefit is the planner will already know where the leak is coming from, i.e to plan a seal replacement.
On the outage PM (also completed with MAINTelligence on Android or iOS field devices) we recommend the following for critical gearboxes at the specified intervals:
Check overall gearbox cleanliness- Monthly
Check oil levels- Monthly
Check for oil leaks- Monthly
Check and replace the desiccant breather as required- Monthly
Check the physical level of the gearbox- Every 6 months