Gearboxes Loosing Oil

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