Engineer Ralph Harty had the distinction of two major derailments with the same train on the Brooten Line in the 70's. (Superior, WI to Glenwood, MN, 200 miles total..) I believe this was what encouraged the rail defect use on that line. They ran the rail detector over the Brooten Line (Moose Lake, MN to Brooten, MN portion of the line. 80 pound rail.) the rail from Moose Lake to Brooten averaged twenty-two defect to the mile. This was back in the 1970's. They ran out of replacement rail and bought rail from the BN that had been ripped up on a branch line.  Rail profile was almost the same, with the exception it was a quarter of an inch higher. That, along with the line not having seen a tamper in years was not entirely a pleasure to ride over.  With all the low rail joints, rocking back and forth latterly, and the mismatched rail you needed to wedge yourself between the seat and the wall. Going over the rail joint your teeth would chatter if you didn't sit slack-jawed.  The Roadmaster didn't want three axle locomotives on it either.
Although I did have six three-axle 3,000 HP locomotives once with one hundred empty grain cars to Glenwood. There was a ten MPH speed restriction over the Kettle River. When the green flag was called out by the conductor I was at a whistle post for a crossing. Every time I advanced the throttle a notch, you could feel the train lurch ahead. All six units were on line. I was only able to get throttle six of eight notches when I went over the crossing at forty mph, track speed. Not bad for 10 to 40 in 1,320 feet with 100 cars.
With all this bad rail the speed on the Brooten Line was dropped from 35 to 10mph from Moose Lake to Brooten, about one hundred thirty five miles, with a whole slew of slow orders of 5mph. Twenty-eight of them at five mph. I would line the slow orders up on a clipboard I brought with and tear them off as I exited each one. Trains were usually 120 cars both ways at that time.  It took two days to get to Glenwood and two days to get back. The halfway layover was Onamia, MN. Setting the train brakes in some of these slow orders going East with loaded grain hopper to maintain five mph was down right tempting fate to keep the train in one piece with sixteen thousand plus ton trains. This is where I became creative with applications. On the engines with 26L with maintaining features I would ride the hump from the six pound den-tent. (This first hump from the running position is called the six pound notch). I didn't look at it, I would use my index finger to tell where it was at. This would be about a eight to nine pound reduction with a 90 pound train line. After exhaust ended I would release it counting seconds in my mind (One - one thousandth, two - one thousandth, etc.) and then resetting to the same amount again. Doing this multiple times with wait times between applications and additional seconds of release depending on speed, train length and track conditions. Soo Line ore cars had the old air brake equipment, the newer grain cars had an accelerated release if a ten pound or more application was made. What the accelerated release did was dump air from the emergency portion of the car air reservoir into the train line to propagate a faster release.  Doing this set, release, and the set with ten or more pound applications was real tricky with the accelerated release, but it could be done. This kept the train stretched, even through shallow sags. I did this for twenty-four years and never tore a train apart. I even stretch braked ore trains this way when there was a 100 car limit. On longer ore trains I used forty retainers in the SD position (SD – Slow Direct) on the head end. Soo Line at that time did not have any engines with dynamic braking.

I image when cabooses were still used the hind end crew appreciated it. One trip with a Superior Engineer deadheading in the caboose from Dresser to Superior remarked to the Conductor why the slack wasn't running in or out anymore, his reply “The Fireman is running the Engine now”.  I rode many a caboose and knew what it was like with different Engineers.  
The worst stop while a Brakeman on the GN back in the sixties, was at Cohasset, MN. We had two hundred fifty empty forty foot box cars going West, and the speed was about twelve to fifteen miles per hour when a piece of scrap metal laying between the rails parted the air hoses between the engines. I was in the cupola at the time. Stop was about instant with the brakes in emergency at the head end first with the slack running in before the train line dynamited on the caboose. The four total caboose end windows shattered (two on each end), the back door, which opened inward, tore the lock hasp off, and was open, the coal stove was ripped off the floor with stove pipe flying all over, the  large batteries in the cabinet went through the interior wall and the caboose being of wood construction, all the dust in the cracks was airborne with viability down to about five feet. Luckily I was partly braced, but did end up in the seat in front of me, uninjured.

On engines with 24rl or 6blc brake equipment using the feed valve or riding the release hump to maintain brake pipe pressure is what I used. Riding the release was not fully in release position choking off the air supply enough so as to maintain the brake pipe pressure at the pressure set during the application, this was the trickiest of procedures!!!  The Soo 24rl valves didn't have the optional maintaining feature.  (I believe these were repurposed off steam engines). On 26L Brake Valves when making applications it was actually referencing to a 100 cubic inch chamber in the brake valve itself. Sometimes you would get one that leaked down. That meant that the train line reduced also. I would watch for this during air tests.  On long downgrades this was a problem. That's when you would use the feed valve. You would make the application, and when it equalized, you cut the brake valve out, moved the handle to running position, backed the feed valve off to match the current brake pipe pressure, then cut the valve back in. I don't think the railroad mechanical department thought too much of that procedure, although I did try dumping the air with the valve cut out and it did work on that one engine I tried it on. A 26L brake valve set for 90 psi train line equalizes at a 26 pound reduction, hence the name 26. Set for 75 psi it equalizes at about 21-22 psi reduction. 6Blc valves had a main reservoir pressure to the brake pipe position to the left of the running position.  You had to be careful not to overcharge the brake pipe. If you did, brakes would stick on. This was a good way to have a accelerated release on the old air brake systems that didn't have the accelerated release built in. And NO, I never tore a train apart doing this during my twenty-four year career.  Jack Peterson hogheaddotnet

Fun Fact:  The reason why all Class A trucks have airbrake systems in place are because of how successful it was to slow down heavy trains of any size.

I think your style of drawing it out, back of the napkin so to speak, lends itself well to getting people with no prior knowledge to understand what you’re talking about! It’s a great introduction to a very important concept, thank you so much for making these videos! 😁

These videos should probably be required training material for everyone coming into operations at railroad museums, they're very well done at building a basic understanding of how the systems actually work in a way I haven't been able to find yet outside of being on the trains themselves.

I think level 0 is actually "trains can stop fast so it's fine to sit on the tracks!"

I've been a train fanatic for 44 years, I've been a truck driver for 20 years (which is kind of relevant moving heavy weight and working a lot with air braking technology) but I have never fully understood how the mechanics of railroad automatic braking works, until I watched this video. No matter what I was told, I always defaulted back to thinking of how my truck and trailer brakes worked. Thanks for this in depth but laymen explanation. And, the art does the job that it's meant to do.

George Westinghouse was a genius

excellent explanation! i watched 44 minutes about a topic that will never be of any use to me in my life and i loved it. your simple drawings surprisingly work very well to get your points across

I am a train driver in Switzerland.
We know brakes and the techniques like the automatic brake too.
I think you explained the brakes perfectly. Good job!

The periodic recaps are key to what makes these videos so good. Makes it really easy to get back into the video after a distraction.

As a retired railroader I think your tutorial on air brakes was great. Strangely enough I was just going through an old Western House catalog on pre 1900s air brakes.And my favorite expression for putting a train into emergency is Wipe the Clock. 😁

one nice thing about vacuum though is that, if you have no vacuum, all your brakes are on, if you have no air, and no charge in the Aux res'... then you have no brakes and you've got a runaway

Absolutely loving this new series. Keep it up Hyce, you're the man.

watching these videos makes me want to revisit the strasburg railroad museum just to see all these on the different trains.

For 37 years I worked as a truck mechanic and I made a career change in '08. From then on I worked as a millwright in a steel mill. There I worked on overhead cranes. On weekends we had the responsibility for derailed trains so we were witnessing much of what you've described. Those poor guys driving locomotives were fired for derails. They would normally get the job back but wow. Through the years there I noticed that the brakes on trains were essentially bigger versions of truck systems. That is probably an oversimplified description of what I saw. I never was able to talk to someone knowledgeable about the train brakes on a mechanics level. The RTO (remote train operator) operators were always new and couldn't give much info. Your video has shined a light on some of the things I had been trying to put together about the systems.
Like I said about working on trucks I didn't really look into it much but the FMVSS manual for trucks also covered rail cars and locomotives.
Thanks for your video it's answered a few questions that I've had on the subject.

I miss level 11: How an automatic brake of simple concept (or from the early days, the ones with simple comparision between reservoir and train pipe) can be exhausted by multiple applications of brakes without appropriate re-charging in between applications. And how the brakes can fail if left in lap due to slowly discharging the train pipe and brake reservoirs over time without brake application.

Love these 10 levels videos! keep up the great work!

Feel like I’m getting trained for an actual job by listening to Hyce.

Much appreciate your lucid explanation.  As a brakeman working as holiday relief one summer (CPR) I must have had to do some learning but have to thank you for correcting a misunderstanding of the brake system I've carried all these years.  (How many years? Well, just a few years earlier I shoveled coal at least once on a tired yard engine in shunting service and thanks to Youtube now also have a much clearer understanding of how injectors work).

Anyone who thinks that this is long video should consider that airbrakes in trucks(at least) is a level of licensing all on it's own