In a recent thread, I mentioned once working on inventing an automatic air coupler for freight cars. I was inspired by David P. Morgan who on a number of occasions, lamented that the so-called automatic coupler is really not automatic because it still requires manually coupling the air hoses. The air hoses do have ingenious “glad hand” connector fittings on their ends that enable them to uncouple automatically when cars separate, but they still need to be coupled together by crouching down between the cars and connecting the two hoses together. So, at that point, I perceived that the only reason such a device was not in use was that nobody had ever perfected it. Certainly the need was obvious.
So I put some thought and drafting work into it, and began welding up a prototype out of 3/8” steel. The concept loosely followed the existing glad hand operation, but rather than aligning the ports and twisting the connectors to compress them into sealed connection; I was intending the mating connectors to slide together in a liner fashion as the two cars came together. This approach posed considerable challenge in providing sufficient gathering and guidance to align the two connectors for mating. So I decided to abandon it and build a new prototype.
The second prototype used a funnel-like feature on one side of the coupler unit and a protruding pin on the opposite side. So when the two coupling units faced each other on two opposing car ends, each pin faced a the wide end of a funnel feature. I had the funnel features about 8” in diameter at the wide end, and narrowed down to 2” in diameter at the narrow end. The protruding pins were sized to fit freely into the 2” end of the funnels.
By contrast, I think a proper fully-automatic coupler for freight is just now seeing practical application. And part of my reasoning is precisely the oil-train threads that you started some months back.
Where you have a situation that involves variable-length consists of a single type of equipment, perhaps operating in dedicated trains (which is the operating model I increasingly see proposed for oil trains) you have the ideal application for SOME form of appropriate automatic. That might be a market for one of the modern European designs – but those are inherently designed for compatibility with non-North-American aspects like SA3 and buffer/screw link, and not with legacy ‘Janney’ couplers. Not lost on me, at least, is that proper ECP brakes, and their required piping and control, would be inherently supported by the automatic connection feature regardless of arrangements that might be made to make the vehicles or consists nominally or ‘emergency’ compatible with single-pipe Westinghouse brake.
Making something like the dedicated oil-train brake system compatible with ‘interchange-standard Westinghouse’ is an interesting design issue, which I gather you did not consider in your design efforts. (On the other hand, I think maintaining brake seal integrity in an automatic connection over the permissible knuckle slack may be less of an issue than you make it out to be.) How will a Westinghouse single-pipe air hose be connected to a nominally automatic head? And how will the control signals in the air be carried through the ECP system?
Euclid, take a look at the Russian coupler, it has very little slack (which is a GREAT thing) . The Russian coupler is US designed and is a very nice design. Also take a look at the Tomlinson automatic.
You raise several interesting points that I am still thinking about.
But I have some thoughts regarding one point: If a certain type of rail car were dedicated to unit trains without the ability to operate in mixed consists, they could have enhanced features without need to make those features compatible with all rolling stock. This would permit far greater enhancement of such non-interchange rolling stock than would be possible if the enhancement had to be fully interchangeable with all rolling stock.
The one type of train today that is begging for performance enhancement is the crude oil train. The traffic level is great enough to justify unit trains, and the oil presents a major hazard for fire and explosion. This hazard could be mitigated by improving train performance in many ways. Better couplers, brakes, trucks, tank configuration, parking securement, and train monitoring all could improve safety.
The one improvement that stands out as obviously advantageous in reducing the hazard is ECP brakes. ECP brakes reduce the potential for derailments, and that is surely advantageous. I don’t believe that ECP brakes will ever be adopted for full interchange service with all rolling stock. But if oil trains could be relieved of the burden of needing to have interchangeable rolling stock, ECP brakes could be added to them with great benefit. I realize there are strategies for a dual system of ECP and pneumatically controlled pneumatic brakes for use during a universal changeover, but that is a big burden, and one of the reasons why I believe a universal changeover will never happen.
Euclid - I read through your thoughts 3 times and I understood all of it. Randy, too. Overmod was way above my pay grade.
However, I am following this because it is interesting and simple enough that I might learn something. Hasn’t been all that many years ago that I learned about male/female electrical conductors, which, I think, is pretty much what you are describing with the funnels and pins.
W/o going beyond that, would the funnel and pin set up take the everyday abuse of coupling and uncoupling? I don’t know what glad hands are made of but they obviously are pretty sturdy.
Yes; that’s partly inherent in what I was saying (or at least thought I was) about running the dedicated oil consists. The ‘catch’ is that there will be times that the special cars may have to operate with other equipment – for example, if a few cars have to be moved from one lane to another, or if some point traffic isn’t sufficient to demand a dedicated consist and power 100% of the time. There is also the question of how defective or cut-out equipment will be moved.
As you know, I have no hesitation in advocating special ECP brake control for dedicated oil consists – how did you succeed in getting the points across at the hearings? I am surprised there is not more use of ECP on dedicated coal trains (and I expect this to be one of the first ‘growth areas’ for acceptance of the OTS ECP gear for oil trains), and of course there are benefits for many forms of intermodal service.
I personally don’t really believe in designing ECP that is ‘fully compatible’ when run in any consist including single-pipe Westinghouse; what I’m talking about is emergency or compromise compatibility just for those times a complete or integral consist can’t be arranged. A possible intermediate stage is the use of ECP ‘modules’ every so many cars in a Westinghouse-equipped consist to give some of the quick release and isolated or rolling recharge benefits of ECP once the control modality on the locomotives and FREDs is widespread. I don’t expect
Yes the funnels and pins would need to be very robust, probably made as steel castings just like the knuckle couplers. The air coupler will not see the level of loading anything like the knuckle coupler, but it will get banged around as the pins and funnels align themselves.
This air coupler would be mounted from the bottom of the knuckle coupler, and hang low enough to clear the pin lifter of the knuckle coupler. The air coupling itself cannot have any independent movement of the two pieces that connect the ports for the air stream. Those two pieces have to be connected as though they were one. Yet, the mated knuckle couplers can move up and down several inches in relation to each other. They can bend side to side in relation to each other. And they move toward and away from each other a couple inches as the train slack runs in and out.
Therefore, the mounting frame connecting the air coupler to the knuckle coupler needs to be pivotal for an up/down movement, side to side movement, and a fore and aft slack movement in line with the train.
That slack movement needs springs to push the air coupling blocks out from the car end as far as they go. When two cars come together, the air coupling blocks meet first; then they are pushed toward the car ends for a couple inches until the knuckle couplers meet and close their knuckles. At that point, the air couplers will have compressed their springs to the point where the compressed air will be incapable of forcing the ported blocks apart and leaking air.
When the slack runs out in the knuckle couplers, the springs will relax somewhat, but still have to be strong enoug
I am somewhat familiar with the Tomlinson coupler, but never really analyzed it. That little motion graphic is quite informative. It does appear to have no slack. I think it is also called the Wilson coupler.
I was thinking that the Tomlinson = Russian SA-3 = Wilson. But I might be wrong.
No , The Tomlinson and the Russian SA3 couplers are two different designs however combining the two and making them stronger shouldn’t be that hard considering the designs are there and proven in their current applications.
You’ll get a lot further if you look for references to “Willison” and not “Wilson”. Willison was an Englishman, from Derby, and the first patent on his coupler came before WWI. Apparently NACO (National Castings) in the United States sold a large number of Willison couplers to the USSR in the '20s – they then copied and ‘improved upon’ the design to produce the SA2 and then SA3.
Tomlinson has nothing to do with either of these; it’s a double-hook transit coupler that, in my understanding, operates on a different principle and has different strength.
Before yuse guys get too involved with your designing, keep in mind that many railcars out do use slip-joints in their trainlines. These slip-joints, like anything else, are subject to failure. They can leak and when they do, they can cause quite a bit of trouble in train handling. So much so as to cause a runaway.
So, will all of you design engineers do the operating engineers a big favor and please keep those slip-joints to yourselves.
Slip joints are not going to work very long in a real-world railroad application, although they are fine if people are prepared to keep them scrupulously clean and free of dings and nicks. And ice buildup. If the gasketing material holds up in ambient temperature. Etc.
It ought to be easier than it is to find good illustrations of these different kinds of couplers. But here are 2 links to similar webpages for a good starting point:
Doubt that a regular Tomlinson would stay together for the load that Mookie asks about:
115 cars at 286,000 lbs. gross weight (143 tons) = 16,445 tons (18,113 tons if they’re 315,000 lb. = 157.5 ton cars instead).
16,445 tons x 1% = 164.45 tons drawbar pull in a ‘static’ mode - no acceleration, change of grade, slack run-in or run-out, etc., which is 328,900 lbs. That’s within the strength of most modern US couplers*, but at a
Here is the current embodiment of an automatic air coupler by the FRA called the Tri-Coupler. It combines the pulling coupler with an air connection and an electrical connection.
The cad model illustrates it on the first page and photographs are presented later. I am surprised at how small the funnel and pin is. You can see how they deal with the three directions of coupler movement when coupled. The up and down movement is eliminated by the use of Type F couplers which have interlocking features to eliminate vertical movement of one coupler relative to the other. Then both the side to side coupler swing and the coupler slack action are accommodated simultaneously by the set of four compression springs.
Paul: Thank you for the information. I had looked at those photos earlier, but never having been very close or able to put my hands on a coupler, I am a little limited - obviously. But drawing on my not-so-good memory, years back my Dad told me that the grade leaving Lincoln south down to St Joe - around Roca was, (I am trying to remember) - a 3% grade? It didn’t sound like a lot to me at the time, but he assured me that it really was. This was before DPU and longer unit trains.
I do know BN or BNSF did a lot of work on that grade to lower it down, but do not know how far down they finally got it. So I was hazarding a guess that it might now be down to about 1% or maybe a little less? Is there some way to find out this information? BNSF runs a lot of coal that way and always with a DPU.
FRA has 3 sets of requirements concerning End of Train devices. One for grades of less than 1%. One for grades from 1 to 2% and another for grades greater than 2%.