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14 Speed Steps - The Quest to Be Different

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14 Speed Steps - The Quest to Be Different
Posted by Mark R. on Wednesday, August 09, 2017 9:53 PM

What with the talk of 28/128 speeds steps, 14 speed steps is actually a very viable option if you want to control your trains realistically. Think about this ....

A very prominent model railroader in the commercial press (name witheld) uses 14 steps for truly realistic operation. The trick ? He has his momentum set really high - almost to the top of the scale. The first 8 steps are the same as the 8 notches in a real engine. With each of the first 8 steps, the prime mover (if you have sound) increases by one notch. All that momentum smooths out the jumps between steps.

A real engine does not have 128 notches to select a real fine adjustment of speed - it has only eight. What if speed step 4 is too slow and speed step 5 is too fast ? Well, you do the same thing a real engineer does - you continually alternate between notch 4 and 5, the huge amount of momentum will keep you in the middle.

I had the golden opportunity to run some six axle power on a night shift once and really saw the reality of this. Speed limit on the line was 30 mph. You just kept your eye on the speedometer. If you started to go above 30, you stepped it back a notch. Once you dropped below 30, you bumped it back up a notch. The speed change was not instant by no means. This was done almost continually on the entire run.

If you have some time to play, try this out on one of your engines. It will take a bit of getting used to, but the level of realism is astounding - especially if you understand how a real engine functions. 

Mark.

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Posted by tstage on Thursday, August 10, 2017 12:28 AM

Mark,

While the above would work for diesels, how would 14 speed steps be applicable to steam locomotives?  I see them as two completely different animals...

Tom

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Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Posted by gdelmoro on Thursday, August 10, 2017 6:14 AM

Interesting perspective.

For me, I probably don't NEED 128 and 28 is probably plenty. I just like to make sure everything is working and the capability is there - IF - I wanted it. I do have one Bachman that is smother when assigned 128.

BTW how many notches does a steam engine have?

Gary

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Posted by rrinker on Thursday, August 10, 2017 7:15 AM

 The only problem with the 14 steps and lots of momentum is the general lack of the corresponding brake. That's changing, but thus far only in sound decoders. And despite there even sometimes being two brakes to correspond to the train brake and the independent, it's really always an independent brake since any braking action can only be applied to the powered loco with a decoder. Does it matter? Maybe not, since the physics doesn't really scale.

 The 14 steps argument is one I remember from the early days of establishing an NMRA command control standard (discussions taking place in, among other places, the CompuServer model railroad forum - anyone else remember that?). 14 steps is plenty, real locos only have 8. But the physics doesn't scale, real trains have lots of momentum. 28 steps was added, then a couple of US companies got 128 added as well. At least out of the box, it can be seen in many of the MR reviews that using 128 steps results in smoother starts and slower minimum speed. Now, can a real loco run at .5mph continuously? Even the slow speed control used in things like flood loaders don't run that slow. But there's that whole illusion thing, and pesky physics. Model locos don't coast, either, other than by simulated momentum, and that really needs to change as the cut of cars gets longer and longer. Unless the crew is really bad at their job, they generally don't slam into cars at 10mph to couple up. And things like a pull to check the hitch - if you only have 14 steps and momentum to do this, how can you do that? Open to step 1, and as soon as the loco beings to move, back to step 0 - ah but that deceleration momentum is going to get you and the train is going to move anyway.

 Maybe picking nits, but using 14 steps seems to oopen as many other holes as it closes. And there is the steam loco issue - most aren't truly continuously variable, there are only so many notches in the quadrant that latches the throttle lever, but it's way more than 8, or 14. And of course Baldwins with their air throttles (back to diesel). Perhaps the answer is that new realistic throttle that Iowa Scaled Engineering is working on with Loksound. Their demo video shows some pretty realistic motion - at least for a light loco.

                             --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by gdelmoro on Thursday, August 10, 2017 11:04 AM

Glad to have Randy on this forum, he's full of information, experience and knowledge. Thanks for the posts

Gary

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Posted by selector on Thursday, August 10, 2017 11:59 AM

Steam throttles don't work anything like notching, and neither do the locomotives themselves.  For slower yard work, shifting, getting from one track to another in a complex or yard, the hogger just cracks the throttle and leaves the real speed control, the reverser, in the full forward (full cut-off) position.

If the hogger wants more power and speed, he cracks open the throttle a bit more, maybe one quarter of the way out.  At some point, if he wants to control the use of steam to be more efficient, he begins to back out the reverser to shorten the cut-off.  When running at constant speed out on the main with substantial trailing tonnage, he will probably have the throttle wide open, but he controls the speed using only the reverser. At most, the typical steam throttle has perhaps four/five positions: cracked, cracked a bit more, half-way open, and fully open for full power mainline running...but controlling the speed using the reverser/cut-off for efficient use of both fuel and steam.

So, while the throttle is technically infinitely variable within its range of motion, it practically is not for a couple of reasons: firstly, it is not a notching lever but a long lever intended to work against a strong spring and strong steam pressure behind it.  They don't pull out easily; anyone who has watched what happens in the cab of a steamer sees the often-two-armed strong tug and repeated jerk to get the throttle to crack, and then to crack some more.  Secondly, once a steam throttle is open about 20%, the loco gets all the steam the cylinders can handle at the full cut-off position and at slow cycles inside the cylinders.  Controlling the valve admission duration via the reverser keeps the pressure high, but allows the steam to expand and do more work against the face of the piston.  At faster track speeds, having the throttle wide open or only mostly open is immaterial because the flow of steam to the cylinders, if the hogger is doing his job, is severely limited via short cut-off of as little as 15%.  This means the valve admits steam only for 15% of the full length of stroke of the cylinder, letting the steam expand and provide more energy against the piston as the piston travels ahead of it.  It's much more efficient.

I won't expand on coasting, but it involves using a vacuum breaking device called a snifter. 

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Posted by 7j43k on Thursday, August 10, 2017 2:40 PM

I had a chance to operate a steam model with TCS sound.  The owner had it set up so it would coast.  He had a separate brake.  It was totally fun.

When you shut off the throttle, the exhause sound went WAY down and soft.  And the loco just coasted, slowly stopping WAY over there.  Unless you used the brake.

Very nice.

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Posted by 7j43k on Thursday, August 10, 2017 2:43 PM

While real trains might not run continuously at .5 MPH.  They DO go .01MPH.  For a short time.  As they accelerate and decelerate.

So, we really DO need models that can run super slowly.  For a few moments.  I have very few that can do that.  They have a tendency to.  Just.  Start.

 

Ed

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Posted by Mark R. on Thursday, August 10, 2017 6:02 PM

Randy - Did you actually take the time to try the concept and really give it a chance ? I'm assuming not, and just making assumptions why it won't work very well. I also assumed correctly that the idea wouldn't gain any acceptance here as well, but I thought I'd put it out there just the same.

I've tried it and will admit it takes some getting used to working it. But it does work very realistcally. Do I use it myself ? No .... because I don't want a variety of new operators to have to pick up on it in short order. If I only ran my layout solo, I probably would in a heart-beat - it's fun once you get the hang of it. That being said, this "famous" modeller I mentioned in my opening post forced HIS operators to learn it.

Mark.

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Posted by tstage on Thursday, August 10, 2017 8:53 PM

Mark R.
What with the talk of 28/128 speeds steps, 14 speed steps is actually a very viable option if you want to control your trains realistically....

Mark R.
....I also assumed correctly that the idea wouldn't gain any acceptance here as well, but I thought I'd put it out there just the same.

Mark,

Let me ask you the question a different way: Do you think 14 speed steps would work with a steam locomotive?

It's important to me because I model both steam and early diesel.  While I could see the concept work with my Alco HH660, Balwin VO-1000, or Alco RS-3 switchers, I don't see it as being very practical with a 4-6-4 Hudson.  Maybe 28 speeds steps and heavy on the momentum???

Tom

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Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Posted by CSX Robert on Thursday, August 10, 2017 10:24 PM

tstage
Mark, Let me ask you the question a different way: Do you think 14 speed steps would work with a steam locomotive? It's important to me because I model both steam and early diesel.  While I could see the concept work with my Alco HH660, Balwin VO-1000, or Alco RS-3 switchers, I don't see it as being very practical with a 4-6-4 Hudson.  Maybe 28 speeds steps and heavy on the momentum??? Tom

You could run your diesels with 14 speed steps and your steam with 128.  You don't have to run everything with the same speed steps.

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Posted by tstage on Friday, August 11, 2017 12:00 AM

Robert,

That was my point.  Currently I operate all my locomotives at 128 speed steps with minimal to no momentum.  If I did operate them at 28 I would definitely add momentum because the jump between speed steps would be very noticable.  At 128 I can replicate my own momentum.

Tom

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Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Posted by wjstix on Thursday, August 17, 2017 4:59 PM

Of course, not all diesels used 8 notch controllers. IIRC, early Baldwins had a continous throttle that could be fine-tuned similar to what we can do with our DCC controllers.

 

Stix
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Posted by Mark R. on Thursday, August 17, 2017 6:18 PM

Thanks for the replies. As I fully expected, no one would actually program one up and give it an honest shot, but rather find reasons to NOT use it or that it wouldn't work. That's fine. I just thought maybe someone might venture outside the box and check it out - there has to be a lot of DCC users that aren't running steam or Baldwins.

That being said, I run all my engines on 128 steps with a lot of momentum thrown in and my top speed set to about 80 on CV5. Just having read that someone so prominent in the model railroad press was using it, I had to give it a try. At least I tried it and could voice an opinion based on my experience rather than an assumption. I'll admit it did work rather well once I figured it out, I just wasn't comfortable with having my operators needing to adjust ....

Mark. 

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Posted by rrinker on Thursday, August 17, 2017 8:33 PM

 I'll give it a try when I have a place to try it - a piece of flex track clipleaded to the DCC system isn't enough track to actually get a feel for it. When the layout is more than a slow speed branch line I intend to set top speed on everything to something approriate for the type of loco it is. I haven't even been able to try out any of the new Full Throttle sound projects, with no where to run right now. Everything currently has a good bit of momentum with 128 steps, which is how I've been simulating what Full Throttle does, sort of, since witht he previous versions of the sound projects the prime mover was not subject to the momentum setting. I can crank the throttle to get the prime mover in notch 5 or 6 while the loco just barely starts to creep with its train, and as the loco reaches the desired speed I throottle back to keep it from going too fast and also dropping the prime mover back to a lower notch. 

 Baldwins were quite advanced, just too different and not compatible with others which is why the railroads weren;t that into it. The Baldwin air throttle was effectively automatic - in fact worked a lot like the way I run my sound locos, and considering the one I run the most with frequent throttle changes IS a Baldwin. With a Baldwin, there was no need to regulate the throttle to prevent slipping. The engineer could yank the throttle wide open and the system automatically applied as much power as it could without slipping. Modern locos have that nooow, with the fancy electronic controls and ground speed sensing radar and whatnot, Baldwin did it (ok, so a modern loco might be able to put 99.99999% of maximum power down...) without electronics more complicated than a relay and a resistor. Good info here: 

http://baldwindiesels.railfan.net/throttle/index.html

                                    --Randy

                         


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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