Yellow Hydraulic Seals

[RoninB4]

I have a question for the collective and particularly for the experienced hydraulic members. I'm rebuilding the directional control on my Ford 1900 that was equipped with a spool/shuttle type directional valve for the FEL. Fairly straightforward to dis-assemble and clean but there are two yellow O-rings in the body at the exposed end of the spools. To my inexperienced eye the color might indicate a different compound than the usual Buna-N per the application. The location is in the attached photo (pardon my poor editing skills).

Offhand I would think that these O-rings not only need to seal but also have better wear/abrasion resistance due to being exposed to the elements (dirt/grit) and the constant friction from the spool/shuttle ends. I'm supposing that the color (yellow) indicates that a different compound than Buna-N was used. I've had many instances of specific seals in kits being a different color, I've never had to source one by material. The OEM valve maker (name escapes me) was not in business any longer when I looked it up. There are other compounds available (Viton, PTFE, etc.) and I'm at the limit of my knowledge, advice is welcome. Thanking all taking the time to read this.

 

[oldnslo]

Are those round seals like standard O-ring or more of a rectangular seal like a rod wiper?

I have seen a yellowish material used for seals but do not recall what material they were.

 

[Eagle1]

I think yellow is just choice, I know you can order almost any type in a variety of colors.
Captain O-Ring LLC - O-Rings, Custom O-Rings, Color O-Rings
or
The O-Ring Store LLC, We make getting O-Rings easy!

 

[WranglerX]

Check out McMaster for "O" rings, if they don't have it, it probably does not exist....

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

 

[RoninB4]

I've already checked most of the sources for these, different material was offered at most of them. That's why I posted this question. They are round in cross section and a common enough size. I'd like to avoid ordering 100 of them when I only need 2, did that when I rebuilt the FEL arm cylinders and have pleeeeenty left over.

As for it being merely a choice of color, that may/may not be the case. I've rebuilt a lot of contraptions in 40 years of working in machine shops and sometimes the seals are a different color so you know the material is specific for that application/location. I don't know, was hoping for greater knowledge from the collective than my paltry level of experience.

Maybe color means nothing, this is one of my first encounters repairing an out-of-production tractor where an OEM kit wasn't available and the seal had to be sourced per what material the O-ring is made from. The seals on the hydraulic cylinders were different colors and you could tell some of them sure had different physical properties when seating them into/onto location.

If a more definitive answer doesn't come along I'll likely try a Buna-N and see how it holds up. I would still like to thank the 111 members that took time to read my posting and those that answered trying to help me.

 

[oldnslo]

Ronin
Do they feel like different material that plain ole nitrile (buna N) rubber. Disogrin (spelling?) polyurethane is a material we used years ago but I do not remember the color but do remember it did not feel like standard rubber. I believe had better wear properties in high temp situations but again not 100% positive on that either.

 

[RoninB4]

Ronin
Do they feel like different material that plain ole nitrile (buna N) rubber. Disogrin (spelling?) polyurethane is a material we used years ago but I do not remember the color but do remember it did not feel like standard rubber. I believe had better wear properties in high temp situations but again not 100% positive on that either.

-They may not be original, early 80's vintage seems like it should have deteriorated by now. They do seem a bit more dense than Buna, not as easily dented with a thumbnail and less "squishy" if that makes any sense. There's an O-ring at each hose fitting on the control body that appears to be regular Buna-N (black in color) so why would a different color be used at the spool/shuttle end? This is what first caught my attention.

-Not at all familiar with this material, Disogrin seems to have excellent properties. Do appreciate the info, thanks.

 

[oldnslo]

Disogrin was also used for rod wipers and that position on the spool is kind of a combination rod wiper and low (tank) pressure seal. Agree who knows if original on a machine of that age.

 

[RoninB4]

Disogrin was also used for rod wipers and that position on the spool is kind of a combination rod wiper and low (tank) pressure seal. Agree who knows if original on a machine of that age.

-Since these O-rings will have to fit into the body in a "captured" undercut in the bore the OD of the seals (O-ring) will be much larger than the bore itself. My description is poor (should work up a cross section image in CAD to explain) but does this make any sense? The captured undercut is to prevent the O-rings from just popping out when the spool comes out of the body.

If this makes any sense then my question is just how pliable Disogrin is. If it's stiff then attempting to squish/collapse them down to fit inside the bore may very well deform or split them. Materials that are relatively soft (like Buna) can stand to be collapsed and the "memory" of the material allows it to pop back into shape.

I'm asking this because Disogrin is somewhat expensive and I'd hate to ruin them if they aren't suitable for the application. I had a seal on the hydraulic cylinder piston that was incredibly stiff (wear resistant material) and I had to fabricate special tapered guides to allow slow/even expansion just to fit them over the piston. Material like that makes me nervous when I have to stretch/collapse it more than it wants to. Excess force = split/damage/deformation.

What I'm asking for is the opinion of someone that's worked with this material before. The voice of experience is always worth listening to. I greatly appreciate your participation in this conversation and/or anybody else that wants to chime in.

 

[etpm]

-Since these O-rings will have to fit into the body in a "captured" undercut in the bore the OD of the seals (O-ring) will be much larger than the bore itself. My description is poor (should work up a cross section image in CAD to explain) but does this make any sense? The captured undercut is to prevent the O-rings from just popping out when the spool comes out of the body.

If this makes any sense then my question is just how pliable Disogrin is. If it's stiff then attempting to squish/collapse them down to fit inside the bore may very well deform or split them. Materials that are relatively soft (like Buna) can stand to be collapsed and the "memory" of the material allows it to pop back into shape.

I'm asking this because Disogrin is somewhat expensive and I'd hate to ruin them if they aren't suitable for the application. I had a seal on the hydraulic cylinder piston that was incredibly stiff (wear resistant material) and I had to fabricate special tapered guides to allow slow/even expansion just to fit them over the piston. Material like that makes me nervous when I have to stretch/collapse it more than it wants to. Excess force = split/damage/deformation.

What I'm asking for is the opinion of someone that's worked with this material before. The voice of experience is always worth listening to. I greatly appreciate your participation in this conversation and/or anybody else that wants to chime in.

If I was you I would take the time to go to a place that sells hydraulic seals. Trying to figure out a seal just by its color is no the best way to go. For example, Buna-n and EPDM are both black. Plus, even seals made from the same type of elastomer may have a different hardness. Take your seal to someone who knows. They can measure the durometer and get you the proper seal.
Eric