Gearbox vents

I am not sure I understand your question. Would you please explain about checking remote vents?

What machine and application is this?

Hi Bill

We have been researching this area now for the past 5 years and have found that this is the cause of 95% of the damage we see in the field,
We commenced working with a filter manufacturer and in association with developed filters that under test will deliver 1µm @ 99%, 0.2µm @ 80% efficiency using cellulose media,
Huge amount of data accruded here and the only system we can get to work 100% is bladder bag breathers where as the drive is sealed,
anyone who wishes email and can send how to make your selves lab@rttech.com.au,
with good quality breather filters, < 1 µm, we get 3 months and the hard particles will work through the media,
when we mount directly on hard working drives with oil temps 70-80°C the oil mists rapidly damage the filter media causing breather change,
remember the expansion rate for air is 10% for every 10°C change in temp, it's a very soft air flow,
so we often recommend the breather be remotely mounted,
20-30 feet away no difficulty,
the hose diameter is not critical we often are using normal air line poly hoses with the push on couplings, the remote filter will prevent the oil mists from damaging filters and the breather filter then can be mounted in a "clean" area to assist with filter life and drive cleaness, the sub micron filter we developed are $15 each, we tested. cut open and imaged filters worth $100-200 and all were allowing the critical sizes or dirt through in 3-4 months so the idea with the inexpensive filters is to replace every 3 months or when the particle count in the drive commences to elevate,
Once you get the breather filtration correct the oil storage shed is next path for contamination in the drive
Regards Rob S

Hi Rob
We have been using 10 micron Beta 2 Fuel Filters as gearbox air breathers, have looked at these ?

Hi

the difficulty with 10µm breathers on a hard working gear drive is the oil film generated is less than 1 µm,
in a contaminated environs a 10 µm breather on a heavily loaded drive will give us repeating oil changes short term and long term bearing damage,
we must keep out any particles larger than the oil film or we'll be chasing the drive maintenace wise,
Best way appears to be simply plug small drives with < 3 litres or so of lubricant, medium drives 100 litres of lubricant is lung breathers and large drives or where lung breathers are impractical celluose < 1 µm media.
The Australian environs is mainly volcanic and up to 80% of the particles can be very hard inorganic crystals,

Regards


Rob S

rttech.com.au

Hi Rob
I agree with you that in a perfect world we should be using 1 micron air breathers, however in extremely dusty environments these would clog up in no time at all and when we are talking about a thousand or so it becomes an expensive exercise, I'm however interested in the bladder type provided it's protected from the environment, do you have any info on them?

We are fortunate with the type of lab we run as we have been completing filter media analysis on breather filters (& Oil Filters) for several years. We image the filter when received and systematically open the filter canister with roller cutters and work our way down into the filter media with digital cameras and the microscope. The reason for the work was tracking debris into drives and this resulted with us manufacturing a new breather filter with Donaldson USA, the filter performance is 80% @ 0.2 µm and 99% @ 1 µm.
What has been learned from the work is the filters don't actually clog up, what happens is the filter media has "snag points" that catch particles, once these "snag points" full up the dirt and debris just travels straight on through the media,
we often hear the comment that the filter works better with a bit dirt in the media, that is not what we see, @ 200X the voids in the new filter media appear the size of the doorway and the particle we are attempting to prevent entering appears the size of a tennis ball in the doorway sized void in the media indicating once the catch points in the media are full the dirt and debris travels straight through. This work has shown the best media for gear drive and transmission applications is cellulose because of the random shaped fibres, synthetic media presents very round even fibres that at the micro level we are working at make it difficult to catch particles.
You cannot compare gear drive and transmission breather vent applications with other types of breather applications hydraulic or otherwise because of the very soft air flows generated, the expansion rate for air is 10% for every 10°C change in temperature creating a very soft flow completely different to a luffing hydraulic ram where the air flow could have several tons of force pushing the air through the filter.
This work has lead onto new breather technology we are at present testing on a dozen or so applications where we have several years of data which we can compare with over the next 3-6 months.


Regards


Rob S

www.rttech.com.au