O-Ring "class" in IH parts book?

I'm getting ready to rebuild the hydraulic lift and power steering assist assemblies on my IH 354 and am confused about some o-ring descriptions in my parts book.

Here is a typical book entry:

352 221 R1 "O" RING, 9/16" x 3/4" x 3/32" (class 6)

I understand the sizing alright, but what is "class 6"? Is it o-ring material? I expect most of the seals in these assemblies are buna-n (nitrile). I don't want to pay many dollars for single o-rings that should cost a few cents unless it is necessary for the specific application.

How do I find dimensions for o-rings that are called out by part number without the description? It would be easier to have dimensions than to measure grooves and old o-rings to come up with a fit. It's not hard, but I could have the seals purchased and on hand before the disassembly begins.

Thanks for your insight!

Well if ya want the correct parts then ya get the correct parts . As for me when i am charging someone to do the job they expect the job to be done wright the first time . so i do not have the time to play the game of gee i wonder if i can cheat and save a buck here and fifty cents there and hope it does not come back . I was not the one that designed , engineered it or the one that built it .I am just the guy that has to fix it.

Where is your example O ring used?

Try going to the 354 parts catalog on-line and looking up the parts, then click on the individual part.

Typically (but not always), the dimensions will be shown, as well as the durometer rating.

BTW, the current part number for that O ring is 238-5113, @ about a buck.

354

If you can see the colored dot on the old O-ring, that would tell you the durometer... 50, 70, 90 or whatever. Chances are you can't though.

Bob,

That o-ring is in the lift control valve cylinder head assy. I used it as an example.

Thanks for the link to caseih parts. I've found most of the info I need to cross to industry standard o-rings.

The tractor vet brings up a good point about genuine parts when you're in the business of satisfying customers. But I'm just me, and I can't see paying $5 for a single o-ring at caseih when I can buy 100 for $3.50 from mcmaster-carr. There appear to be just a few specials I cannot cross to standard (because the dimensions aren't there).

I don't expect to become a tractor expert, but I do have 28 years experience with pressure systems up to 30,000 psi, both liquid and gas. That puts me 10 points behind at the starting line

Not tryen to be a smart Arres here George but time is money and since this morning's post i could have run down to the friendly local Case I H NEW HOLLAND or what ever they are calling them selfs today got the parts i needed stopped had lunch came back and got the job done and out the door stopped and had a beer them come home and have supper to just prove i could save five buck ?? Now if ya want to save on O/Rings ya can get the O/Ring kit thru parker that has the Fat o/rings for thirty bucks , then ya can get the kit that has the skinny O/Rings for thirty bucks and ya can get the kit that has the O/Rings for Cat for thirty five bucks. and for really big O/Rings they are just twelve miles from me . BUT the Case I H / N/H dealer is seven and with fuel at 3.99.9 a gallon It's the Case I H / N/H dealer

Agree 100%. I tried the fix cheap route once on an auxiliary valve and spent 2 days in the process trying to get the right o-rings. Finally went to IH and got the right set to fix it. An hour and I was done, and the cost not that much.

(quoted from post at 22:33:54 04/22/14) Not tryen to be a smart Arres here George but . . .

Click to expand...

That point is becoming less clear.

It is one thing if somebody is paying you to work on a machine, another if you are tinkering on an old tractor on your own time or as a hobby. In that case, time spent identifying and obtaining a standard part is just as good as time spent sniffing a paint can. The ultimate conclusion of the "time is money" argument is that we should scrap the old tractors, buy a new one then hire somebody to drive it. By the way, my nearest CaseIH dealer is at best about a 2 hour round trip, so running over there for an o-ring isn't likely to be the quickest way to get one.

Back to the original question, o-rings are commonly made of EPDM, Buna-N (nitrile), Viton and silicone and a few other things. Each has advantages/disadvantages. If you google a couple of those materials (at the same time) you will probably find several comparison charts. Buna-N is the usual choice for hydraulics. I thought class 6 had to do with food grade and medical use, so unclear why it pertains to a hydraulic part in a tractor. Maybe there is some aspect to grade 6 I am unaware of.

I certainly fall into the category of the "tinkerer" in this case. My nearest dealer is 90 miles away. I'm retired, so I have the time to tinker. Bottom line - I enjoy it.

With about 3 hours of effort I was able to identify 15 different standard (AS568A) o-rings by dimension and durometer. I am specifying Buna-N because it is compatible with the fluid, the operating temperature is low, and most of the seals are static. If something fails after a few tens/hundreds of hours I can get a different material like viton.

I have to buy minimum quantities of 25, 50, or 100 rings in each size. Cost breakdown: 1225 o-rings from McMaster-Carr for $53.65 gives an average cost of 4.3 CENTS per o-ring. Sure, I'm buying many, many times more rings than I need, but I'm still paying less than at the dealer for a few. Some of these will be useful when I get around to rebuilding the next system.

For those parts that I can't cross reference (3), I will call and pay the dealer. Either way, the post office or UPS will deliver what I need.

I may learn something here, but learning is what it's all about. There's some principle involved, too. The dealer or mfr. buys the same o-ring for 4.3 cents, puts it in a bag with a part number, and charges me from $1 to $10 for it. I have trouble with that...

AS568A is the Aerospace Standard (inch) published by the Society of Automotive Engineers (SAE).

Sorry to be stirring the pot -

I found a source online where I ordered in more reasonable quantities of 10 ea. The most expensive rings were $.40 ea.

Total order came to $19.60 plus $10.00 for shipping.

http://www.oringsusa.com/