Category Archives: train cars

MAX coupling

Not dead. Just resting.

Coupling Info and FAQs

This is going more in-depth on an old anatomy post where couplers were mentioned. The coupler at the end of each MAX car (with the exception of the A-end of a Type 4) allow for both a mechanical couple and an electrical couple between cars. The mechanical couple is what physically keeps the cars connected, and the electrical couple is what allows the cars to communicate. By design, both a mechanical and electrical couple need to be established in order for the train to move.

Although the Type 1s, 2s, and 3s are capable of being coupled into consists longer than two cars, MAX trains do not run in longer consists longer than that. There are rare exceptions to this (e.g. getting a disabled train out of the way), and yes, some 20 years ago trains were brought back into the Ruby Yard in longer consists but the length of city blocks downtown and the subsequent design of all the train platforms limit the length of MAX trains to two cars.

Note: There are several categories of TriMet employees who are qualified to couple and uncouple cars (operators, supervisors, mechanics, etc) but for simplicity I’m just going to go with “operator” in this post.

The Electrical Couple

The coupling process won’t make much sense without describing this first. At the top of the coupler is the electrical coupler head. Under normal conditions, this is either coupled to another train or covered, but occasionally one with the cover up will sneak through ground inspection without being noticed (or alternatively the operator will forget to switch it back after uncoupling cars).

Electrical coupler head on a Type 2 with the cover raised

There are two positions for the electrical coupler head – electronically isolated and electronically normal. If one or both electrical heads between coupled cars are in the isolate position, there will be no electric communication between the cars. When coupling cars, the first goal is to establish a good mechanical couple, and to do that the car doing the couple will be electronically isolated at the beginning of the process.

This switch inside the cab controls the electric coupling of the train

Coupling cars

First, as with just about everything else done with the trains, the operator will get permission from Control before coupling. Next, they’ll do a ground inspection of the car they will be coupling to in order to ensure there aren’t any safety concerns, such as personnel working on or around the car. They will also make sure that the car they are going to couple to is set to electronically normal. The operator will make three safety stops in the coupling process (because hey, you’re essentially about to drive one train into another train) – the first one car length away from the car being coupled to; the second about 10 feet away, and the third at about 3 feet away to ensure that the couplers of both cars are aligned. Then very slowly, the operator will bring their car forward and couple mechanically to the other car (this happens automatically).

The operator will then perform what’s called a “tug test.” As mentioned in the last section, the car that the operator is in is electronically isolated. When there is no electrical communication between the trains, the brakes will apply. In a tug test, the operator remains in the coupled cab and attempts to put the train in reverse and move. The test is a success if the cars do not move – this shows that the mechanical couple was correctly done because it’s holding the operator’s car (which should otherwise be moving backward) to the car with the brakes applied. If the operator’s train car moves backward, it’s either because the mechanical couple failed and the cars came apart, or the cars were not electrically isolated. A visual inspection of the couplers will also be done.

Next is the “trainline test” which is also done from the coupled cab. The operator will now set the car they are in electrically normal (remember that the car they coupled to is also electrically normal). Now there should be communication between the cars, and the easiest way to test this is to open and close the doors. In the yard, this will be done on both sides of the train, and the operator will watch to see that the doors in both cars open. On the mainline, this will only be done on the doors that are on the platform side for safety reasons. If the trainline test is successful, the coupled cars are ready to go.

The finished product: Two successfully coupled train cars. Note how the electrical coupler heads are raised and the covers are on top of the coupler. When the cars are separate, those will slide down over the electrical head.

Uncoupling Cars

A simpler process – again, always done with permission from Control. The operator will do a safety inspection and then press the “uncouple” button in the coupled cab (pictured in the first section of this post, it has a cover over it to prevent it from accidentally being pressed). Next the operator will back their car from the other one to separate the mechanical couple.

Mainline uncoupling

Uncoupling on the mainline is not preferable, but is sometimes necessary in order to cut a bad car and leave a “sportscar” train in service. The exception to this is, of course, the Type 4s, because they can only be fully operated from one end so they can’t be uncoupled on the mainline.

And then the 4s

The coupling and uncoupling processes above apply to the Type 1s, 2s, and 3s. The 4s are more complicated – as you can see in the above picture, they don’t match the coupler heads of the rest of the fleet. Under each Type 4 cab (the A-end) is  a fold-out mechanical coupler head which can be used to mechanically couple a 4 to any other car to be towed or pushed. Type 4s can’t be electrically coupled to the other types of cars, and are the only cars that have the step of connecting the canon plugs of the cables on either side of the mechanical coupler head to electrically couple.

Mechanical coupler head under the A-cab of a Type 4


What’s that bag over the coupler head? (seasonal)

These covers basically work like shower caps and are put over the coupler heads in snow/ice conditions to prevent ice from building up on the couplers. Metal covers used to be used but I don’t remember how long it’s been since they were.

Why is a coupler off-center?

deformation tube bend

The coupler heads are designed to be able to bend around curves in the alignment, so if you see a coupler like this, it isn’t broken. They should be straightened out during a ground inspection, but sometimes one gets missed. The operator or a supervisor will move it back into place when they see it.

What happens if the train cars come apart?

If that were to happen, they stop – the default position for a train car is “stopped” and the loss of electrical communication will apply the brakes in the trailing car, much like how the tug test works. I’ve heard some people are not comfortable riding in the trailing car due to “runaway train” fears if the cars separate, but the purpose of the tests done after coupling is to ensure that that doesn’t happen, so this isn’t something passengers need to worry about.

Today I learned: The more you write the word “coupler,” the weirder it looks.

Storage tracks

Ruby Junction Yard

Somewhat cliche “Art School 101 perspective” type picture, but I like it anyway. MAX trains are stored either here at Ruby or at the Elmonica yard. The tracks are numbered and the spaces are lettered (e.g. storage track 5 E & F) so you know, for example, where to store your train when returning to the yard.

Also, you may have noticed a new link at the top for rail terminology. That had originally been one of the first posts I made and then promptly neglected, so I dug it out, updated it (still a work in progress though) and modified it to be a headline link. Theoretically it can serve as a sort of index of posts to make this site easier to search, because after almost 2 years, there’s a lot of stuff here…

Another 4-car MAX train, Type 1 version

This is too interesting not to share. Remember the 4-car Type 4?

Well in response to that, here’s an old video that shows a 4-car Type 1 train, courtesy of mrksvideos, who recently left this in a comment on that old post. Since I don’t expect people to go back and skim old posts for new comments (though there are some good ones!), I wanted to repost this here so that you all could see it. This is a train move that hasn’t been done for 20(ish) years. In addition to that, I really like this because it’s rare to see video of MAX during the wheelchair lift, pre-low-floor car era. Really glad mrksvideos recorded it and posted it.

mrksvideos’s description of what you’re seeing:

Back in the day Tri-Met ran Light Rail (MAX) to the far end of the line in Gresham, and had a few 2 car trains terminate there. The trains would pull down to the tail track at Cleveland Avenue and park there. Then, another train whose day ended there as well would pull down to the parked 2 car train and couple up. They would then take the 4 car train to Ruby Junction for the night and tie up. This practice ended a long time ago and I have seen no other record of this type of move anywhere. This video was shot at the west end of the westbound platform of Gresham City Hall station sometime in the 1990’s when the old Gresham lumber mill was still around across the tracks in the dark. Enjoy!

And for reference, the tail track at Cleveland, which is long enough to store a 2-car consist on each track, though it is not used very often these days:

Cleveland Tail Track


And now, back to your regularly scheduled (more or less) technical posts.

All about the announcements

“Pioneer Square. Doors to my left. TriMet ticket office and visitor information available weekdays. Bus and MAX service on 5th and 6th Avenues”

APACU, Type 2

AACP, Type 4

The audio and readerboard announcements and external signs on the trains (Types 2, 3, and 4) are controlled via the APACU in the train, or Automatic Passenger Announcement Control Unit. In the Type 1 trains, the external signs are all manually scrolled and there are no readerboards, but the audio announcements are still set through the APACU (which will also set the readerboards and signs in  your trailing Type 2 or Type 3). In the Type 4s it’s actually called the Automatic Announcement Control Panel, but since AACP isn’t an especially pronounceable acronym and I’m old and resistant to change, we’re sticking with APACU.

Excerpt from Blue Line Paddle

The APACU is typically programmed at the ends of the lines, though it can also be set mid-route when necessary. The above picture shows part of a paddle, or schedule, for a Blue Line train. The #99 refers to the route code used to get a train to Hatfield, and the 0019 refers to how you set the APACU to get Blue Line announcements for a westbound trip from Cleveland to Hatfield. For a route code, it doesn’t matter if I’m out at the airport, leaving the Elmonica Yard, or anywhere else- if I’m directed to go to Hatfield Gov Center, my route code will be 99. Doesn’t matter where I’m starting from. The APACU, on the other hand, is based both on where you are and where you are going. It is location-dependent where you’re starting from in order to announce all of the stops, so each of those destinations to Hatfield has a different APACU value.

Eastbound Blue Line, BTC Pocket track

An operator can reprogram the APACU along with the route code if their train gets rerouted so that their announcements match the new route. The above picture, which is a little hard to see in the dark, shows the pocket track at Beaverton Transit Center (which is typically used only by Red Line trains) with a Gresham-bound Blue Line in it. I forget exactly what the problem was the night I took this picture but westbound trains needed to do turnbacks at BTC, so Blue Line trains headed west to Hillsboro were directed into this track instead of the westbound mainline so they could turn back east. Even though this train was headed for Hillsboro when it came into Sunset TC, the route code was changed to send the train into the pocket track at BTC, and once the operator got here, the APACU was set to have the stop announcements match the eastbound movement back to Gresham.

This train is not in service

The route code and APACU codes are two different systems. Because they function separately, this is what allows an out-of-service train to go wherever it needs but keep a “NOT IN SERVICE” message on the external signs. And no internal announcements either for out-of-service trains – I remember that had been a bit of a shock for me when I was in training and we took out-of-service trains on the mainline for the first time to learn where the platforms were and when to begin braking for them. I had assumed that I could just listen for the announcement of an upcoming platform to start braking since I had made the association that the announcements usually come around the time that the train begins slowing down for a platform approach, but nope, no announcements when your APACU is set “Not In Service”. Had to learn where everything was without that kind of help!

So how does it work?

No GPS involved – the announcements work by counting how many times the wheels turn between platforms. In the older cars, the counter resets each time the doors are opened, and APACU won’t advance forward if the doors don’t open at the current platform. However, the Type 4 announcements will still advance forward even if the doors don’t open at a platform.

In the event of running reverse traffic (e.g. east in the westbound track) the APACU can tell that you’re approaching a platform but it doesn’t know enough to tell you that the doors are going to open on the other side of the train, so in those cases the operator will have to make a PA announcement to manually correct the error. This is a very infrequent occurrence.

On routes that change color or go out of service, the scrolling of the external signs happens automatically. For example, if you’re on a Yellow or Green train headed south toward PSU, the signs will automatically start scrolling to Out of Service after you leave City Hall/SW Jefferson with no action required on the part of the operator. When they get into the turnaround at Jackson, they’ll set both the route code and APACU for where their train is scheduled to go next.

On the Type 4s, that square with a circle in it…

… theoretically should indicate that the train changes color (e.g. from a Red Line to a Blue Line at Gateway because it will go to Willow Creek or Hatfield, not terminate at Beaverton TC), but yes, sometimes a 4 will display that only on one of the LED boards or in a context that makes no sense:

Red square, nothing in the circle to… Expo?

Could be the result of a random error, from taking power under a section isolator, the phase of the moon, etc. I was joking about the phase of the moon part.  Mostly. The 4s will also sometimes display a self-test error on one or more of the LED signs.

The 2s and 3s will get their share of announcement errors as well. Sometimes the audio announcements will be fine but the readerboards will be stuck on a stop, or one of the exterior signs gets stuck. You can try resetting the APACU, but that doesn’t always work for everything. The good news is that it doesn’t affect how the train runs until a mechanic is able to fix it.

Sign stuck between two red signs… on a Yellow Line train

This will be a new platform opening Spring 2012

Car 235, how are you?

Not that I’m the kind of person to anthropomorphize the MAX cars, but if I did I would totally pity car 235, who’s like the poor guy that always happens to be in the wrong place at the wrong time.

If you’ve seen it around, you may have noticed that 235 looks a little different from the rest of the Type 2s..  the others all have either the old paint scheme:


Or full-body ads:


235 is a little different – it could almost pass for a type 3 as it’s the only 2 that’s rocking the new TriMet blue and yellow color scheme that all of the type 3s are painted in (though one side of it has had an ad for a while), and the mirrors are still those of a type 2.

235 and some other Type 2

235 on the Yellow Line downtown

It wasn’t always like this.

Don’t remember where I found this, but this is an old shot of 235, looking like all the other Type 2s

But then, one day in 2005, 235 had a tangle with a fire truck in Hillsboro. It sustained severe damage in that crash.

Not my pics, I don’t have bigger versions of them

235 was repaired and re-entered service. As far as I know, it had a relatively uneventful life after that, until a few years later, when it was the trailing car of the train that derailed at 11th Ave.

Well at least it wasn’t the lead car?

Just along for the ride, so to speak

And then yesterday, a semi-truck loaded with cars crashed into 235 at 10th and Washington in Hillsboro. I’ve heard the operator is ok. It also was not his fault, which is also good news, and as far as I know the damage to 235 wasn’t too bad, aside from the windshield.

Pictures courtesy of Hillsboro Fire & Rescue

But we can rebuild it. We have the technology.