Hump Yard Operation


Alcomotive

Alcomotive

Grandson of an ALCO Builder
Does any one here have an operating hump yard on their layout or at their clubs layout or friends house? I would like to see some pics if so... I was wondering about this...I think a while back I saw Macjet on a layout that had one? Not sure. Interesting modeling I would think...:rolleyes:
 
Yes, there used to be a group that exhibited one at the Springfield MA show each winter. My memory of it is "Looked great, ran awful". They had no way to operate the turnouts rapidly, no reliable uncoupling, and the "retarder" was in the form of an air jet controlled manually. The major trouble with this kind of thing is that gravity doesn't scale, so you end up with the cars hurtling down the slope at a million mph. It just doesn't look right unless you invent something really sophisticated. The group still comes to the show, but they rebuilt the layout as a flat yard.

Here are some pix (and is that Mom at the retarder control? She doesn't look too confident):

dryhill1.jpg


dryhill2.jpg
 
Somewhere, I saw the same layout and I had exactly the same impression. A lot of work was put into it and it didn't look right and most of the cars spent their time either derailing or flying into another cut of cars. As John said, the weight of HO cars and length of the grade you'd need to properly model an HO hump yard just doesn't pencil out.
 
Thats the Dry Hill MRR club. I use to be a part of that group and the reason that the hump is gone is because the Amherst Belt Lines said they had to shrink the layout. Now the DHMRR is on their own and I am no longer a member due to the owner of the club (The guy in the second pic) having some major issues. I am not sure if the club will still be there this year but its doubtful.
 
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I see having ground throws on there....with todays technology with JMRI, DCC switches that problem could be solved. As for the grade on that hump I would question the scale there.

The retarder system in real life are a bunch of shoe like clamps that are operated by air and they have motion detectors for speed check. At least the yard in North Little Rock, AR does this. For retarder system...once the grade was corrected I would think creating a something similar to the real thing using DCC, electric eyes diodes and a mechanism that "clamps" the flanges a bit like the prototype. Hmmm it definitely would takes some thought and doing. I am sure some where some one has done this....so many talented people out there....
 
I'm planning to model BNSF's Barstow hump, not sure how I'll do so yet.

I was thinking of shaving the overhead clearance of the cross under on the hump to the bare minimum to fit locomotives, and notching the cross under down into the terrain. Not to mention, I'm not planning air, but rather brush bristle retarders.
 
From my observations, there are two major issues. You need a long grade down from the hump. I would guess the top of the hump was at least 10" above the yard. You really need to have no more than a .25% grade not have the cars get out of control. Using the standard formula, it would be Rise divided by the Gradient(%) = Run. Let's say you could keep the top of the hump at 8". To maintain a .25% grade, you'd need about 36 feet of run. That's a lot of layout before you even start your yard. That would be just to get the the ladder tracks. I'd guess you'd be looking at somewhere around 50 feet total with the yard.

The second issue is retarders, Air just doesn't work because any amount of air that will actually slow a car will probably derail it. I think some kind of very gentle brush retarder has a chance of working but you need them not only on the hump but down in the yard to slow cars to their final momentum. You'd have to come up with some kind of system that could calculate the forward momentum and raise as many brushes as needed to keep the car with an acceptable speed limit. Since all cars don't roll as freely, you'd almost have to rig up some kind of optoelectronic system that could measure the car between two points and then use DCC to automatically raise the brushes until the car slowed but not so much that it would stop. You need this system all the way from the top of the hump to each yard track so we're talking about a lot of detectors and brushes. I'm sure it could be done by someone with a lot more talent than me but it would be a major projects.
 
8" is huge Jim. I was thinking somewhere in the range of 3.5"-5" at the top of the hump on mine. You only need approximately 3" to clear an ho scale locomotive on the cross under. If I can factor in a 1" under cut, then the top of the hum can be at the lowest, 2.5" from the level grade of the yard.

As far as the grade calculator goes that I used, .25% at 2.5" of elevation change takes up 83.33'. Remember grade remains the same. 1" for 100" = 1%, so, .25% would be 400" for 1" of rise.
http://www.scalerailsonline.com/ModelCalc.aspx
 
I've got an idea how you could slow them down.
How about short burst's of air under the rails just in front of a car rolling downhill.
You would have to have all of the cars at the correct weight. They would have to be able to roll free/no dragging wheels. Be able to control the air bursts w/a very small venturi thru holes under the rail.
I know there's a way to do it. How about magnets? You could have a small plate mounted under the cars & a strong electromagnet under the rails.
Just a few thoughts.
Larry
 
Larry said:
I know there's a way to do it. How about magnets? You could have a small plate mounted under the cars & a strong electromagnet under the rails.
Just a few thoughts.
Larry
Click to expand...

I was thinking the same thing. You wouldnt need strong ones, maybe only 15 lbs of pull to slow them them down, and why electro, if they were standard you could just run them the full length it would just add drag to it and slow it down....I have been doing a lot of research in magnets, especially in making them replace internal combustion, it can be done if you know how to harness it. But I think magnets would work great. Mike
 
Josh, you're right, my calculator was missing some digits. So even if you could keep the total rise to 2.5 inches, you'd still need 250 inches, or or about 21 feet before you hit the yard. You'd also need to add space to the other side of the hump where the train would climb to the top. Say that's another 5 feet. Add in a 10 foot yard and it's still about 46 feet total space needed for a just a small size hump yard. You also need an entire new ladder track at the far end of the yard and at least two departure tracks for making up departing trains, then a connection back to the main line. Now you're looking at about 55 feet. Just the space requirements are daunting. The whole control system would still need to be worked out. I can see this being a near lifetime job to get a realistic hump yard working.
 
I spent a large portion of my 20s and early 30s railfaning on the hump at the CSX Tilford yard in Atlanta. I often wondered how this could be modeled - efficently. reading the above posts confirmed it would be an undertaking that requires a significant amount of modeling skill, engineering savy, time and space.
i found a couple of videos that have the basic concept down. they seem to have overcome the uncoupling obstacle, but are still not prototypical because the lack the retard factor. the HO scale one claims to have one, but the trains are still avalanching down the grade, which also looks a little too steep.

Z - http://www.youtube.com/watch?v=lYAX9-glOuM&feature=related

N - http://www.youtube.com/watch?v=B8YfSXjH7FA

HO - http://www.youtube.com/watch?v=KfWCHpoo-z8
 
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NS, unless every car rolled down the hump track at exactly the same speed from the start, how would a magnet system work? It would slow every car by the same amount. Some cars that are headed for the furthest ladder track would have to roll faster and those headed for the central ladder track would have to roll slower. Cars would have to roll slower or faster depending on how full the yard was so they aren't crashing into cars if the yard is full or running out of steam and stopping in the middle of the yard track if it's empty. Without some detection system and a variable way to slow down cars, I can't see how this would work. An electromagnet that could vary the strength of the magnet depending on all the other issue I have described might work but, once again, the detection system would still have to be worked out.
 
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Good videos, Airslide, and they all illustrate the basic problem. The grades are too steep and there are no retarders so the cars shoot off like rockets and crash into the standing cuts of cars. No real railroad would ever have cars traveling at 30 or 40 mph from the hump. Since you've spent time at Tilford, I'm sure you know the goal is to have cars travel at no faster then 5 mph and to couple at no faster than three mph. The difference between these two speeds for the prototype is difficult to maintain. On an HO model, even allowing a 20% fudge factor, I think it's virtually impossible without a reliable dectector and retarder system. I'm sure it can, and will, be built some day but I'm not convinced we have the technology to do it any affordable manner.
 
UP2CSX said:
Good videos, Airslide, and they all illustrate the basic problem. The grades are too steep and there are no retarders so the cars shoot off like rockets and crash into the standing cuts of cars. No real railroad would ever have cars traveling at 30 or 40 mph from the hump. Since you've spent time at Tilford, I'm sure you know the goal is to have cars travel at no faster then 5 mph and to couple at no faster than three mph. The difference between these two speeds for the prototype is difficult to maintain. On an HO model, even allowing a 20% fudge factor, I think it's virtually impossible without a reliable dectector and retarder system. I'm sure it can, and will, be built some day but I'm not convinced we have the technology to do it any affordable manner.
Click to expand...

I think your right Jim on the cost factor. I think though we have the capability to build it with todays tech just all about money I think and LOTS of trial and error...;)
 
Give it time guy's, some where out there is a NERD hard at work with his slide rule and computer at hand to come up with a scale working hump yard retarding system! Then will Pat. it and sell at some crazy price that a normal man can't afford! As with all things, the working hump is still out of reach of most! but some day soon!
 
Consider the physics of a hump yard. There is an initial steep section which gets the cars accelerated--something like 5%. This ensures that the cars, which go over the crest at up to 4mph (that's a car every 8 seconds or so) are separated as they go through the turnouts, allowing time for the turnouts to throw between cars. But since the hump can't be reconfigured for each car, they have to be given a generous run down the hill, and then have their speed adjusted by retarders so as not to reach the turnouts too fast, and so as not to hit standing cars too fast either. In a model, we'd probably want to keep some slope until the cars are well down the bowl tracks, just to make sure they keep moving. But if the cars are typically going much too fast when they reach the coupling point, then the hump was too high!

It also seems as though the prototype does something that we often leave out--the various class tracks are arranged to have equal numbers of twists and turns, by use of wye switches. It's even more important on a model, as a rolling car passing through a turnout loses a lot of momentum; but the right way to deal with it shouldn't be to have the car enter at high speed!

It's a fascinating project. I would try to get the appearance in operation as close to the prototype as possible, or it's going to look like little toys, as those videos prove all too clearly. I think the key would be to get the cars rolling at almost the right speed just by using the hump, and maybe retarders wouldn't be needed at all. If the turnouts are on a slight slope, just enough to keep cars moving, then my guess is the hump wouldn't need to be very high--my instinct is less than 2 inches. Its function would be just to get the cars separated to give the turnouts time to operate. But maybe this isn't going to be very interesting to watch?
 
There are also smaller hump yards that don't have underpasses that could be easily modeled. There's one near here with maybe a couple foot rise, just enough to do some running switching.
On my layout I have a yard lead that drops from mainline cork to ground level, and it's enough to send a good rolling car a few feet with a nudge.
As to the air retarders, I recall seeing a layout somewhere that used that system and it seemed to work quite well.
 
.25%

Jim.
I stand to be corrected here but I don't believe that an HO railroad car will do much running on a .25% grade. I don't think your car will know there is a grade??
That's about 1/16" in 25". Water will run and a marble will roll if the surface is smooth????
Boy! your track and your wheel bearings have to be in perfect shape to do any good.
I will do some experimenting today on my work bench.
Mac
 
Mac, believe it or not, I have an industrial spur that has a grade that's less than .25% and I have have to keep a push pin handy because some of my really free rolling cars will take off down the spur. Therein lies the problem. I have other cars that would need a push to get them rolling on a 1% grade and they stop rolling as soon as the grade even starts to level off. I think John may have come out with a good solution. Have a hump with maybe a 2% grade that's short and have the switches in the bowl on maybe a .5% grade, quickly leveling out after the switch. I'm still not convinced you could slow all cars down enough without some kind of retarder but it's a better solution than launching them down like rockets. John's idea about using all wye switches makes sense also, since the amount of slowing by the friction of the car passing through the wye switches would be about the same for all cars.
 
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