Recently(meaning last night) I watched Modern marvels on the history channel. They had the freight trains episode on and they were talking about the north platte NE yard, and how it has a 3 story hill that acts as a sorting station. The tracks are switched and there is a braking system that can slow a car down to 3 mph if needed all run by computer. I guess my question is… can that type of system be modeled? Not so much the automated part of it, but devising a way to separate and slow cars down using common modeling practices. Im sorry in advance if there is a thread like this already.
The New York Society of Model Engineers of Carlstadt, NJ has a layout with an operating hump yard. Jets of air blowing up from between the rail slow cars as they roll downhill to the yard tracks.
Hump Yard physics don’t scale down very well.
Actually it’s been done several times. Check MRs indexes. I think that they even had an article on making one a long time ago. I got to operate one on a guys layout in Detroit and It was really neat. It takes some practice but is doable.
Not using common modeling practices, but it can be done. One of the really hard parts is to keep the cars from stalling before it gets to its destination or slamming into the string of cars already on that track. That is why the scale where the cars are weighed in the real one is so important. Knowing the car weight it knows how hard to brake it to get it hitting the cars in the yard a 3 mph or less. Without real precision instruments and a computer for controlling it seems very difficult. I mean it isn’t going to matter if a real car is +/-100 lbs, but an HO scale box card a +/-0.25 oz is going to make a big difference.
You mean like these? Search - “hump” in “MR forums”.
http://www.trains.com/TRC/CS/forums/1111052/ShowPost.aspx
http://www.trains.com/TRC/CS/forums/699878/ShowPost.aspx
http://www.trains.com/TRC/CS/forums/502624/ShowPost.aspx
http://www.trains.com/TRC/CS/forums/502623/ShowPost.aspx
http://www.trains.com/TRC/CS/forums/747329/ShowPost.aspx
http://www.trains.com/TRC/CS/forums/322981/ShowPost.aspx
http://www.trains.com/TRC/CS/forums/133861/ShowPost.aspx
Interestingly, more than a few NMRA recommended practices (car weight and the [censored] coupler, for sure) were influenced by the work done by a now-deceased modeler who was trying to make a hump yard work reliably in HO scale. By the time I saw it in operation on his layout, he was one of the very few holdouts who didn’t use Kadee couplers.
The key was air retarders - jets of low-pressure air blowing uphill, turned on and off by a timer. A fast rolling car would get the full retarding blast. A medium-roller would get only the latter part, and the air would be off before a slow-rolling car would be far enough down the grade to be influenced. His final version had four classification tracks, all he had need for. There was no reason that the system wouldn’t have supported six tracks or more.
I thought about putting in a hump yard, but the rather low throughput at my subdivision point (and lack of space) canceled the plan. (I might experiment with directed air jets to assist flat ‘kick’ switching. If I get any useful results, I’ll pass them on.)
Chuck (modeling Central Japan in September, 1964)
At the FREMO meeting in Alsfeld you could see a yard with hump.
This guys had good rolling stock and it worked. A big list to many pictures you find here at the bottom of the site.
Wolfgang
Interesting… at last a reason why NMRA H0 weight standards are so massivly high. I’ve never put models on a scale (apart from 1-10) but I reckon that USA?NMRA cars are about the same weight as the equivalent UK 0 Gauge Finescale car would be. I’ve also never bothered to start messing about changing weights… the important things are consistancy and reliability.
[8D]
Dave,That is one reason why I have never followed RP20.1.Like you I prefer reliable operation over extra weight.Also I never seen where the added weight actually made the cars roll or track any better.Also with today’s mixture of car lengths its my opinion that RP20.1 needs to be reviewed and adjusted for modern cars since the length of the cars vary.The Operation sig I am a member of has been discussing this for months with a on going test that was extended till December.
I’ve contended for quite a few years that this standard needs to be revisited in consideration of the advances in truck and wheel technology. I had never heard the hump yard reason, but I know one of the other reasons the weight was so high was to allow reliable pushing of a train especially around sharp corners. It takes much less to push a string of current technology cars than it did a string of Varney’s in 1950.