I have been sorting through fittings I have and trying to put them in some sort of organized grouping. They are mostly AN type fittings, but many of them are also "adapter" fittings that combine two types of thread systems. I have a pretty good understanding (IMHO) but admit that sometimes I still have to check some of them out. It occurred to me that many people have little understanding of our American thread systems, so I decided I would try to explain the basics of the different American thread systems in a manner that would hopefully help others to get a basic understanding of them. Hopefully I didn't screw it up trying to get it explained (to the best of my knowledge) in a fashion that might help some others. So here it is.......... EDIT CORRECTION.......I referred to AN as meaning Army Navy and it should have been Air Force Navy as @DDDenny reminded me below. Just a brain fart from a frazzled old brain......but the correct AN is Air Force/Navy. Some of the charts or kinda small, so click on them and see if they enlarge. View attachment 6317343 EDIT There is a line on page 3 that says "Look at this TAPERED Pipe Chart and notice the Straight Pipe Threads. While editing I put that in the wrong place. It should have been on page 2 above and sjust below the picture of two fittings. It should have said "Compare the tapered and the straight fittings"
Appreciate the time it must have took to write this thread Feel I have a better understanding about the AN fittings and tubing size for sure.
Thanks Mike; I'm saving these charts to my computer so I can find them the next time I need to refer to them.
@ekimneirbo , Thats a easier understanding for those that do not know fittings A&N ,Jic & pipe. Then comes Real complicated when trying to Navigate The catalogs from Eaton , Parker & 5 or so of Aroquip's catalogs. All the different hose's & Application and usage, Then you have the British / European Section
It's one of the curses of living Down Under. We started out using "imperial" units of measure (inches, pounds etc) and most of the stuff I work with uses those types of thread. We inherited some delightful threadforms with our British heritage - Whitworth, British Standard Brass, British Standard Cycle.... as Mater says "they ain’t metric, they ain’t inches, you never can find a wrench to work on them”. Then we went metric (metres, kilograms etc). When I pick through my parts stash, a bolt could be any type. I bought one of these tools, which really helps identifying: The AN fitting stuff has similar challenges. My fittings can be AN (37 degrees), SAE (45 degrees) or the weird 30 degree stuff used on some Lucas piping. Never a dull moment. Cheers, Harv
""We inherited some delightful threadforms with our British heritage - Whitworth, British Standard Brass, British Standard Cycle.... as Mater says "they ain’t metric, they ain’t inches, you never can find a wrench to work on them” I had a old 250 BSA engine that was perfect example! Bought a few of them thread checkers, come in handy..!
A youth spent playing with beezers (BSA's) is a youth well spent. As punishment for my sins, I am adapting three Amals to a Holden grey motor (similar to a Chevy Stovebolt 6). Cheers, Harv
You'd be correct.......thanks for pointing that out...............its just one of those things that my old brain forgot. I'll make the correction.
Thanks for the info! Working with huge ( think 75 foot rams) hydraulic systems and Firetrucks for 33+ years and dealing with farm tractor hydraulic systems for sixty years, I have a good understanding of threads , fittings and adaptors. But I did learn one thing! That is about the JIC vs AN! Back in the day, we had fitting that were called “ areo- quip” , I might have misspelled it. I believe it is the same as JIC. JIC fittings also had a taper on the inside of some of the male fittings that would seal on the swivel fittings! The first time I ran into this, I didn’t believe it! My dealer assured me it would seal…..and it did! Working with hydraulics most of my life I also had to deal with “ flange o’ring “ fittings a lot! In my youth I dealt a lot with feral fittings, don’t see much of those any more. They are coming out now with a lot of new fittings that will probably make the old fitting obsolete! Progress , I guess. Bones
I was a machinist for thirty years for a company that built machinery for the wood products industry, we had our own hydraulics department with bins upon bins of JIC fittings and related adapters, every one was made of steel. Having used AN hardware in drag cars and shifterkarts, the only difference I saw was that AN components were made from aluminum. Over the years some mfg's in the AN industry started offering their fittings and adapters with larger bores and radii, especially in 45 and 90 degree adapters for less restriction, not a real issue for general hydraulic applications where achieving higher pressures were more critical than volume.
Thanks for that information, it's the kind of stuff that can save you a lot of fiddling around for hours. When I was an apprentice one of the first projects we made were thread/clear/tap gauges for "American" (8/32 ect) and "British" (Whitworth) as we worked on both U.S. and British / European aircraft. I still use these gauges nearly 50 years later. I should make some for that "Tool of the Devil" (Metric) stuff, as it is creeping in everywhere here.
JIC and AN are very similar, though AN is made to tighter tolerances. From memory, one of the two has a radiused thread root whilst the other is sharp-rooted. Can never remember which one though. Cheers, Harv
Eh. Army/ Navy is correct. An fittings were invented during WW2. While air force didn't become a branch till 47
I know some people will debate the accuracy of Wikipedia. Have at it! https://en.wikipedia.org/wiki/AN_thread
The Op is what most will deal with. I cant find much that isn't metric now. I have a metric and a SAE pitch gauge. The metric is used quite often. With a history in race cars and braided hoses, you quickly get used to dash - numbers and what threads accompany them. I have chosen to be adept at all that I mentioned. I still have Whitworth wrenches from my British bike days. Looking at the sizing on them will make you wonder what we missed out on. LOL.
That's actually a really good source of info. I'd suggest that Hambers print a copy, especially the chart about AN thread size and put it in the drawer where they keep their threading and fitting stuff................ Would like to clarify one thing. "Note that AN threads are different for bolts and fittings. In bolts the number refers to the diameter of the bolt whereas in fittings it refers to the OD of the tube and thereby have different threads. For example, AN6 bolt has a 3/8 -24 thread. whereas an -6AN fitting has a 9/16-18 thread." That is a correct statement but people should realize that whether a 3/8-24 Thread is being used or a 9/16-18 thread is used.........the thread itself is "essentially" the same whether they are on a bolt or on a fitting. 3/8-24 is 3/8-24 and 9/16-18 is 9/16-18 . It's the AN designation that has a different meaning between nuts/bolts ...........and fittings. Even a a common Straight Pipe thread which is a different thing altogether uses the same thread sizes ...............but its a similar situation to the AN explanation. In a common pipe the designation 3/8 pipe refers to the approximate size of the hole in the pipe, not the external thread. So a 3/8 pipe could have a 9/16-18 thread on it. Where the common pipe varies is that most of the time when using that common pipe, they also have a "tapered thread" in addition to the straight thread version. The tapered thread is the more common type. So while it may also have a 9/16-18 thread on it outside, the taper makes it incompatible with straight threads of any other fitting. Here is a picture to show what I mean. Look at the silver fitting at the top. It"s left side is 1/4 STRAIGHT PIPE. Has nothing to do with the AN (JIC) system, but the thread on it is a 9/16-18 and it screws into a 9/16-18 nut. The Blue fitting screwed into the nut has 9/16-18 threads but its left end has 7/16-20 threads and they screw into a 7/16-20 nut and a thread gage. View attachment 6319784 The two pipe taps in the lower part of the picture should say 1/4 inch pipe tap.......9/16-18 thread.
Mike…how much would you charge me to come to your shop and look around and take notes? You are the most organized guy I ever saw ….with some cool stuff! Bones
No Charge, you are always welcome. Why not attend the Street Rod Nationals this fall and you can come by my place.......but you will be welcome any time.
Thanks , Mike! We have some family matters, I am caring for my 101 year old mother, so my travel options are limited at this time! Don’t feel sorry for me, though! Yesterday, we took here to a doctor and hearing aid appointments and ended up with a couple of hours to kill in town! So what did we do? We took here to a to our bar for a drink! Introduced her to some of the regulars, had a great time! Just don’t tell my sister! Bones
I've been doing automotive and aircraft plumbing since Orville and Wilbur were young. I recently went into an aircraft hardware store and was corrected by the counterpart. I was told that AN was no longer valid. It was now MS! When I asked what the difference was, he replied that AN stop for Army/Navy and MS stood for Military Standard! When I asked what the difference was, he told me that they were still the same but now are politically correct! I guess I am getting too old!
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