Shop Press

Shop Press is the news and idea hub for everything related to working on cars and trucks, focusing on repair, technology, and wrenching lifestyle.

From the creative minds at:


Hot Off the Press

Texas nonprofit helps low-income vehicle owners afford auto repairs

At any given time, about 1 in 5 vehicle owners are delaying some sort of auto repair, with the most common reason being that they can’t afford it, according to the Auto Care Association Factbook. All this deferred work adds up to an estimated $31 billion that drivers...

A day in the life of a service writer (VIDEO)

The hardest job in an automotive shop might just be that of the service writer. Taking heat from the boss, the techs, and the customers isn't easy. That the role is for dynamic individuals becomes apparent quickly when considering the tasks that make up the job. Watch...

Serviceability Hall of Shame: Ford Taurus Spring Shields

The Serviceability Hall Of Shame was born from all the times we’ve looked at a vehicle and realized some usually simple task was going to be nightmarish. It is, ultimately, a response and explanation of the inevitable question, “Good Lord, why?!” Today’s entrant isn’t...

January Automotive Horoscopes

Aries: You may not think of some of your repairs as innovative, but a creative fix is a creative fix. Your outlook is out there, and that's OK. Expect to see someone else cribbing your notes but remember to take it as flattery. Not everyone has the same gift of seeing...

It’s totally fine to run your fuel tank down to empty

One of the pieces of automotive wisdom that’s been repeated by publications and mechanics alike for ages is that it’s not good to run a fuel tank below some arbitrary fill point, like a quarter of a tank. At some point, that probably wasn’t bad advice. But today? It’s...

LOF PSA: Don’t forget the lube job

Please forgive me, because I’m about to be a dinosaur and proselytize for a few moments. Many moons ago, I would have customers request an oil change and a lube job. It was so prevalent that the acronym for this, LOF, is still in pretty common use. (That’s “lube, oil,...

Best of Shop Press 2022

Shop Press officially launched in March 2022, at least if you go by the press release. Between then and now, we’ve published well over 100 articles and videos dedicated to auto repair professionals and wrenching enthusiasts. We greatly appreciate everyone who has...

Geography by way of fittings and couplers

by | Nov 29, 2022

As a little mechaniclet, I didn’t really give much thought to my air tool fittings or their air lines. Yes, the type of tool, the amount of air moving through the lines, and the distance from the compressor are all variables that determine how well a tool might work, but I was just too dumb to know those things. One thing I did know, though, was when I blew up a fitting I needed to ask for “L” style replacements.

As it turns out, that “L” is a grouping Milton industries gave to the style of fitting competitor Lincoln used. Those “L” fittings were common to every shop in which I ever turned a wrench, and that was smack-dab in the middle of flyover country in the Midwest. In time, I learned that style was common to that area, since all of my mechanical friends used that same style at their shops. And here is where I am going to ask for your help: I’d like to know where you are and what your shop uses. Here’s why.

Air line fittings

There iss quite a bit of variation in fittings used across the United States. Image by Josh Seasholtz.

The first time I tried to hook up tools here on the East Coast, I realized my fittings and couplers were all wrong. In the Keystone State, most places use what Milton calls an “M” fitting, which are also called “industrial.” I actually like these much better, because the “L” fittings have a long, narrow tail that breaks when mishandled. Once I switched to the “M” style, I stopped going through so many fittings on my tools.

Male air fitting on a hose.Industrial-style fittings are common in many shops. What do you use? Image by Josh Seasholtz.I learned later that “D” and “G” styles are popular on the West Coast. In researching this article, I also found “Nitto Kohki” fittings are ubiquitous in Japan, Australia, and New Zealand. Luke, a Dorman technician in our Proving Grounds with a bit of heavy truck experience, tells me Tru-Flate-style (“T”) fittings are common in truck shops. According to Tru-Flate, this style has a wide surface that leads to better sealing and longer seal life, and also has lower pressure drops and greater air flow, which would make sense in a truck setting where torque specs are higher.

To put another fly in the ointment, it seems as though many garage nuts feel the Milton “V” style checks a lot of automotive boxes in terms of flow, so those appear to be cropping up in many places without a unifying regional background.

Air compressor with line

Some shops run different fittings on different lines to prevent accidental hookups, like running a paint gun on a line with a tool oiler. Image by Josh Seasholtz.

And now, back to my original request: I’d like to know where you are and what you use, because our Creative Design Manager has agreed to make a map based on that input. I think it might be handy to know what fittings are in use in what parts of the country, and my hope is with enough feedback, we can make a fairly accurate map that’s helpful for any of us traveling to do some work.

Air coupler chart

You can use the handy chart to determine what style you use if you’re not sure/. (It’s also a big help for figuring out what you need to adapt to.) It really only works on the fitting side; the couplers all look similar. Milton Industries image.

So thank you in advance! Just let us know where you are and what you use (and any other places you might know about from your travels) and we’ll record the data points and drop the map in here when we have enough collected.

Related Articles

Notify of
Oldest Most Voted
Inline feedback
View all comments
Click to leave a comment!x

Get Articles In Your Inbox

Subscribe to receive a monthly email summary of our latest Shop Press stories.

Shop Press

Thanks! You're now subscribed.