Help finding o-ring please

[ramdough]

I am looking for an O-ring.

The bought #4 o-ring ms28778-6 thinking that is the right one.



I went to install it and it is way off in size. Either I received the wrong o-ring, or I have the wrong part number. This is for the PTO hydraulic supply right angle fitting into transmission seal

thanks in advance for guidance.

ps..... I would bring it to the store, but the tranny leaks bad when I pull it out. Kind of need to do a quick swap.

 

[ramdough]

Did some digging.


I think it is actually a 3-904 NBR 90 durometer o-ring.


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[frank8003]

3-904 NBR 90
As the name implies, these O-Rings are used to seal Straight Threaded Tube Fittings. ... Straight Thread Tube fittings are often used in relatively high pressure applications, so most often a 90 durometer NBR or FKM O-Ring is specified.
Nitrile rubber (NBR, HNBR, HSN, Buna-N): a common material for o-rings because of its good mechanical properties, its resistance to lubricants and greases, and its relatively low cost.
Parker 3-904 NBR O-Ring 1/4 SAE (0.35 Inch ID X .07 Inch) 90 Dur NBR 30 to 74 cents

 

[frank8003]

O-rings are not rocket science
It is all at your fingertips.

 

[NDT]

O-rings are not rocket science
It is all at your fingertips.

HUH? there are thousands of sizes dozens of material and dozens of profiles and some rocket scientist at Morton Thiokol once picked the wrong one resulting in a national tragedy

 

[frank8003]

O-Ring History original 02132013
Niels Christensen perfected and patented the o-ring.

An o-ring is a solid rubber seal shaped like a doughnut or torus. When pressed between mating surfaces, an o-ring blocks the passage of liquids or gases.

An o-ring is a solid rubber seal shaped like a doughnut or torus. When pressed between mating surfaces, an o-ring blocks the passage of liquids or gases.

Niels Christensen
Independent inventor, Niels Christensen perfected the o-ring while developing automobile brakes. Christensen received a patent for his improved o-ring in 1937, however, manufacturers were not interested until the aircraft boom of World War II. Then Christensen was able to sell his o-rings to the military after tests on a Northrop plane. The simple o-ring enabled a complex technology to advance.

Background O-Rings
Early uses of round, resilient rings for dynamic applications were in long grooves or as seals in between sliding telescope tubes or on pistons where the rings were not confined, allowing them to slide back and forth. These were not effective. Large cross-section india rubber rings were used as gaskets in counter-bores for water-works piping in the mid 19th Century. Thomas Edison's 1882 light bulb patent shows a round rubber ring at the neck of the glass bulb to keep the mercury in and the air out. There is a Swedish patent for an o-ring that is dated May 12,1896.

Dynamic O-Rings
Today's dynamic o-ring in a short rectangular groove was the result of experimental work in the early 1930's Niels Christensen. By the early 1940's, o-rings became the standard seal for the Air force hydraulic systems. This established the basic sizes and design information. In the 1950's, came acceptance for industrial hydraulics, farm equipment, passenger cars accessories, plumbing, appliances, pumps, valves, and many other devices. Today, billions of o-rings are sealing every conceivable apparatus all over the world, in the air, on land, and sea, and in outer space.

O-Rings the Seal of the Century
The o-ring is the most widely adapted seal in history because of its simplicity, low cost, ease of installation, and small space requirements without supporting structures. It is suitable for dynamic or static seals within the temperature limits of elastomeric materials, Successful use depends upon proper groove dimensions and selection of the right compound, or from one's prior experience with similar applications.

 

[frank8003]

HUH? there are thousands of sizes dozens of material and dozens of profiles and some rocket scientist at Morton Thiokol once picked the wrong one resulting in a national tragedy

Engineers didn't pick wrong application, the other 10,800 o-rings worked good.
The temperature at launch was too cold for the design.

The Space Shuttle Challenger Disaster: What Happened? (Infographic)

Chart details the causes of the destruction of Challenger on Jan. 28, 1986.

www.space.com

 

[simp5782]

I am looking for an O-ring.

The bought #4 o-ring ms28778-6 thinking that is the right one.

View attachment 803487

I went to install it and it is way off in size. Either I received the wrong o-ring, or I have the wrong part number. This is for the PTO hydraulic supply right angle fitting into transmission seal

thanks in advance for guidance.

ps..... I would bring it to the store, but the tranny leaks bad when I pull it out. Kind of need to do a quick swap.

What is the part # for the #3 fitting. Its going to be boss. So with that part number I can tell you if it's 1/4 3/8 boss

 

[Guyfang]

mistake post.

 

[ramdough]

Did some digging.


I think it is actually a 3-904 NBR 90 durometer o-ring.


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FYI all,


This size fit. I leaks since.


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[frank8003]

Yeah thats way up there at 41 cents but the shipping kills

3-904 NBR - SAE O-Ring SAE Straight Thread Port O-Ring

www.hydradynellc.com

 

[ramdough]

Yeah thats way up there at 41 cents but the shipping kills

3-904 NBR - SAE O-Ring SAE Straight Thread Port O-Ring

www.hydradynellc.com

I forgot how many I bought, maybe 40 for $20. The local Parker store had a minimum order.


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