I work in a gypsum plant and in our mill areas we are faced with a high concentration of dust. Many of our gearboxes are being covered by this gypsum dust and are not in the best of shape due in large part to seal damage. Also, we are in the process of oil consolidation and have elected to switch to synthetics in most if not all of our gearboxes including these used in the mills. Part of justification for switching to synthetics was that our mill ambient temperature exceeds 140F degrees especially in the summer months. The other part to justify using synthetics would be for extended service life of the oil.

However, I’m still faced with the matter of dust and possible ingression. The solution that I’ve come up with would be to locate Des-case breathers away from the dusty environment then to run vent lines to the gearboxes.

My question is, what are the limitations in regards to the distances for venting a gearbox? Will this type of venting prevent seals from leaking? My concern is pressure build up due to long lines. Has anyone run across similar situations and their findings?

Thanks,
Ron

I really can't anwer the question regarding the length but since there is little movement of air I would think you could do this. I have thought of doing that myself in the past on hydraulic tanks.
Also, Hydac has a new breather for gear boxes which incorporates check valves that vent the box to atmosphere for air movement out but incoming air flows through the element.

GA, What of your success stories with these Hydac breathers and under what conditions are these breathers being tested. Thanks for your initial response I value all suggestions.

Hi Ron
The expansion rate for air in a gear drives is 10% for every 10°C change in temp.

The air movement is a gentle ease of air from the drive as it heats and reverse as it cools.

Extending the connecting lines to the breather filters should not cause any difficulty

Filters should be sub µm or fit a bladder bag.
Bladder bagged breather vents are the best as allowing zero contamination entry as it is very difficult to remove all the airborne contaminates, we have recently completed 2 years of testing breather filters on Rail Drives and the results indicated all filters examined were allowing more contaminates in than what was required resulting in us working with filter makers to improve this.

Bladder bags are the best, how to make is available if you email us (lab@rttech.com.au) and we can send back pdf instruction on how to, down side is time consumming with high labour cost where as ready made filters are easy just fit to the breather hose,

Your idea of finding cleaner air filtered breather vents is very important as if you can you will reduce ongoing oil change work dramatically.

Regards Rob S

Consider the option of using an expansion chamber similar to the bladder that Rob mentions above. The only limitation being the gearbox size.
Check them out here - TRICO
If anybody in Australia wants any info drop me an email.

Also www.des-case.com

I am fighting the same situation now. We went to Expansion Chamber style breathers and the largest is 100cu" which is the size of a large coffee can. So far everything is working fine but concerned that when the hot summer months come the expansion will be too much and seals will begin to leak due to the pressure. Similar contaminates to yours but underground and petroleum coke. Never used the Descase but would more than likely need changing daily.

tHE CONCERN ABOUT FILTER LIFE-CYCLE IS OBVIOUS IN THIS HIGLY DUST LOADING SITUATION.
IF MOISTURE IS NOT A PROBLEM, DO NOT USE A DESICCANT BREATHER, BUT A HIGH-QUALITY BREATHER FILTER WITH SUB-MICRON FILTRATION.
BE CAREFUL, . . LOTS OF SMOKE & MIRRORS ABOUT EFFICENCIES.

Hi Ron


Expansing chambers or bladder bag breather are 100%,

we get 2 years from the bag, 50 µm polyethylene,

I have attached the how to manufacturer bags to this (I hope)Can't won't send, anyone who want email and ask for bladder bag instructions to make onsite to : lab@rttech.com.au

We can provide 100's of WDA microscope reports on the results.

We recently released sub micron breather filters and did not explain the limitation of media verses bags and the maintenace folk on site disconected the already fitted bags and screwed the new breather filters on in place of the bagged breather,

Took 3 months and then all the planetary pressdrives the breather filters were fitted commenced into a fine cutting wear mode that cost us the lubricant in use and the bags were all connected again and the wear stopped and particle counts reduced back to < ISO 17/13 again.

Regards Rob S