Skip to content

Call Toll Free: (844) GO BAART
or (844) 462-2278 | Questions?

Gearbox Leakage: Shaft Mount Reducer Solutions

Share this:

Shaft Mount Gearbox

Without oil, your gearbox is in serious trouble! Heat and friction caused by a lack of adequate lubrication will rapidly cause problems – damaging (or even breaking) the bearings and gears inside your gearbox. Thankfully, fixing gearbox leakage isn’t too hard. Rather than repeatedly topping off the gearbox, or worse – letting it run critically low on lubrication – let’s take a couple of minutes to go over solutions. 

First, examine your system for the oil leak source. If there isn’t an immediate, clear source of oil, you’ll need to start with a blank slate. 

  • Take apart the helical shaft mount reducer and thoroughly clean and dry it. 
  • Ensure the amount of oil is correct, relative to your mounting position and tilt. 
  • Inspect oil seals for damage and replace them if necessary. 
  • Reassemble the gearbox properly. 
  • Get it running and see if the source of the gearbox leakage becomes clear. 

Often all you need is a gasket or seal replacement. Of course, if that doesn’t do the job, you’ll want to explore these other possible causes.

Plugged air passage

Your helical shaft mount reducer needs to breathe. Air and oil inside your drive expand as they heat up, building up internal pressure. This pressure needs somewhere to go – that’s where your breather plug comes in. If your gearbox is missing a breather plug, the air and oil will find a seal or gasket to exit through. 

Don’t skip over this step just because you have a breather plug!  Like anything else in your application, breather plugs get dirty and clogged. Check to make sure nothing is impeding airflow through your breather plug. Clean or replace it if necessary. While you’re at it, double-check that your plugs are completely screwed in and not below the oil level. 

Oil level

Each drive system requires a different level of oil, based on its mounting and tilt position. Regular maintenance should include making sure your oil is at the right level for the machine. 

An incorrect oil level can cause multiple issues. Too little oil limits the ability to properly lubricate and cool the helical shaft mount speed reducer. Similarly, too much oil will keep the machinery from functioning correctly. The gears may end up working harder than intended, which causes temperatures to rise.


Hotter oil and air, in turn, causes an increase in pressure inside your drive. This becomes a vicious cycle. The hot oil doesn’t function normally – causing friction and more heat. The heat makes the oil even hotter – causing more pressure and friction. So on and so forth. As we mentioned, that pressure has to go somewhere. If the system and its air passages are overwhelmed, oil may leak right out your seals and gaskets. 

Breather plug position

One of the more obvious reasons for gearbox leakage – breather plug position – is also one of the easiest to overlook. Most manufacturers sell shaft mount reducers without plugs installed. There’s no way for them to know the final mounting position. The breather plug, magnetic drain plug, and solid plug all have specific locations depending on the position of the reducer. Occasionally these are installed early only to avoid losing them.

Of course, it’s easy to forget to relocate these plugs while aligning the drive and everything else required during setup. If the plugs aren’t repositioned, they may end up below your oil fill level. If that’s the case, the oil will leak right out the breather plug. Thankfully, fixing this is as simple as moving the plug to the topmost hole. 

Seal wear and/or fatigue

Your drive system is full of moving parts – most moving very quickly. It’s only natural for each of these parts to wear out because of friction, heat, and the strain of transmitting the load required every day for hours. The seal is no exception. Over time, as the seal lips pressed against a rotating surface,  they will begin to wear down. 

Normal wear and tear is to be expected. With the quality of our gearing and how long our gearboxes are designed to last, eventually, your seal will require replacement. Sometimes circumstances, such as a more strenuous environment, can even cause premature wear to a seal. If your oil seal looks worn – or you notice leaking around the seal – it may be time for a replacement.

Questions about dealing with drive wear or solving unexpected problems in your drive? Explore more of our Knowledge Base for information and advice.