Base oil seal compatibility with tractor hydraulic systems

[tboar]

Hey, first post for me, let’s see what comes of it… I want to know what seal materials are the most common in new farm equipment’s hydraulic systems and transmissions. NBR? Viton? Polyurethane? I can make an educated guess, but hopefully some of you have real knowledge.

Other surfaces that come in contact with tractor hydraulic fluid include hose inner liners, accumulator bladders, and valve components. What materials are common here?

Of all of these, which ones are most likely to take issue with blends of ester, Group III, and PAO based synthetic fluids?

 

[Fitter30]

https://www.fpeseals.com/faq/a-guide-to-seal-materials
Have dealt with gasket companies like General Gasket in St. Louis they are very knowledgeable about the materials and different fluids.

 

[crashz]

Welcome to BITOG!

I know that Viton and Poly are used in some hydraulic cylinders and valve bodies, but really have no idea what the materials are in a hydrostatic transmission. But if you are using a commercial tractor fluid my guess is that the amount of esters and PAO stock in them is pretty limited. I think that NBR is the seal or O-ring material that would be most likely to be affected by either. In general, commonly used esters tend to swell seals, PAO seems to dry seals, but that is a very broad stroke.

 

[tboar]

Thank you both. With that and the other information I found on my own, I'm seeing these as "common", some obviously more so than others:

NBR, dramatically varying grades/quality levels, some interact poorly with a variety of common fluids
HNBR
Polyurethane
Viton, in areas known to run hot
PTFE
EPDM
PEEK, in some low leakage valves
Teflon, in some shaft seals to reduce friction

 

[greaseguy15]

Are you looking for some particular information? Most tractor hydraulics would be group II base oil with additives but nothing particularly exotic. Seal materials would be pretty much everything you’ve turned up already.