With two sound decoders in my fleet now that support manual notching, I need some help. I know that automatic notching is handy when you don't want to bother, but I want to bother, and I know automatic notching isnt that realistic. So, I have a few questions. First of all, when a locomotive starts moving with no cars behind or a very short consist, does it always go automatically into notch 1? Secondly, when locomotives are in notch 8 to get a long train moving, does it stay in notch 8 when it begins moving, or does it automatically go down to notch 1? Lastly, are notches in any way linked to locomotive speed? Or are they completely independent. For example, does notch 3 put the locomotive into at least 35 mph or something like that (I just threw numbers out there, I don't expect them to be accurate)?
I'm beginning to realize that Windows 10 and sound decoders have a lot in common. There are so many things you have to change in order to get them to work the way you want.
Wikipedia gives a reasonable description of notching, for our purposes. You can get away with jack rabbit starts in your car, but not a mile long train. Starting in notch 8 might tear the couplers off.
Think of it as your accelerator in your car. Once you've outgrown your teenage years and pay for your own gas at $4 a gallon, you start out gradually. The amount of gas you have to give it to drive a certain speed, increases if you are towing your 40 foot RV. A 100 car unit tank train has to run at a higher notch, for a given speed, than a single loco.
I have no real world loco experience, but I expect that when they get up to speed, they back off a little, but not all the way back to notch 1. We have some real railroaders here that will tell us, shortly.
Henry
COB Potomac & Northern
Shenandoah Valley
I am not familar with DCC locomotives so I assume when you are talking about automatic notching you are talking about a feature of DCC. Real locomotives have eight power positions (or notches) in there throttles. There is nothing automatic as the locomotive engineer moves the throttle to the notch he wants to use.
Throttle notches are related to the speed of the diesel engine, not the speed of the locomotive. The faster the engine turns the more power is generated. If you are pulling a heavy train up a grade you may be in the eighth notch for a long time. Typically you start out gradually notching out on the throttle to get the train up to the speed you desire. If you are on a grade and the slack is stretched out you may have to go to the second or third notch, possibly more to get the train moving. As the other responder said you do not try and do jack rabbit starts but increase the speed gradually. Once you are operating at the desired speed, you make throttle adjustments as necessary to maintain that speed.
Starting a 19000+ ton coal train. Two engines (one isolated-not producing power) in the head consist, a single engine at the rear in distributed power mode. All GE 4400 HP AC engines. Grade is mostly level. Notch one produces about 14000 (14K) pounds of tractive effort (TE). Slight movement, not much more than pulling any slack out. Notch two produces about 51K TE. Train starts moving. Before going to the next notch, watch for the loadmeter* to stabilize or slightly drop. (Each notch will give you so much tractive effort. It will build up and then stabilize or begin to fall. At that point you're usually OK to give her another notch.) Begin gradually notching up to reach desired speed. Once the speed is reached, modulate the throttle settings as needed. (As speed increases in a given notch, tractive effort will decline. Unless you're working the engine to it's maximum on a heavy grade.) Some places you may stay in a higher notch. Others you may back off to lower notches. It depends on the territory. The first 10 miles of this trip was on level with slight up/down variations. I dropped down to notch 1 for part of that segment, then into dynamics for a permanent speed restriction, then back into power, working back up to notch 8 to climb a hill.
Later on in the trip, we went about 50 miles in notch 8. For about the first 35 miles, after going through a permanent speed restriction, speed built up to and then stayed about 40mph, with about 46K TE while on a slight uphill grade. The next 10 miles the grade started to increase, the last 5 miles being the most severe. Speed gradually dropped off as the tractive effort produced started to increase. We topped the grade, still in notch 8 at about 13 mph with 100K+ TE being produced.
The rest of the trip was on undulating terrain, with a few good, short uphill/downhill segments. This required being in power here, dynamics there, at times running the DP separate from the lead, etc. But that's for another time.
Jeff
*The modern AC, and a few late model DC with computer screens show load as pounds of tractive effort. DC models with analog gauges (and a few with computer screens) show load as amount of electricity being produced on an ammeter. Either one operates about the same. A notch will give so much load and then stabilize or begin to drop, depending on conditions.
Two things to add. On some trains,especially with older pre AC power engines under certain conditions, it may be necessary to use two or even three or four notches to get the train to start moving. Once movement starts it would be good to notch down some, maybe even to notch one, to keep the front end moving very slowly until you are sure that the rear end has started to move. Otherwise the rear end might be jerked enough to break a knuckle or drawbar.
Older units have the air compressor driven directly from the diesel engine rather than by an electric motor as on more modern units. These older units could be notched up to the fourth or fifth notch in neutral to increase the output of the compressor when pumping up the air on a train.
Mark Vinski
Many are the times that the train will be drifting along at 30, 40, 50 mph with the throttle in idle. I don't know if you can replicate that in model railroading. Then, what about dynamic braking???
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BigDaddyOnce you've outgrown your teenage years and pay for your own gas at $4 a gallon, you start out gradually.
Unless you live northern Virginia on the west suburbs of DC where half the drivers seem to be in a big hurry.
Rio Grande. The Action Road - Focus 1977-1983
I'm no train expert or DCC expert but this is what I think I know by reading varous comments over the years.
The sound of the prime mover in our models is related to engine effort, not speed. So the more a locomotive is exerting itself, the louder motor noises it should make. Obviously with a heavy train, the engine is going to labor a lot before it gets up to speed. Also, it will make more noise if its heading downgrade with a heavy load behind it, but that will also involve dynamic brake noises.
Model producers do a reasonably good job simulating engine noise with notching the DCC throttle, but it also results in the speed increasing along with the noise despite how many cars are being pulled (within reason).
Also, a real locomotive can increase its speed slightly without incurring substantially more noise if its riunning light or with a few cars. Again, noise is primarily related to effort, not necessarily speed.
I assume that's where you want to bother programming the loco. You need some way to increase the noise output without necessarily increasing the speed of the loco, and then execute that command as you are starting a heavy train or beginning a descent (which would include dynamic braking noises too). My simple way of looking at it would be to EASILY increase the prime mover sound independently of the dcc speed step, and either louden up or quiet down the loco depending upon how much load it has given a situation (you know, like a simple volume knob found on analog stuff). I assume that's what the notching programming is trying to do.
I don't think my rambling answered your question.
- Douglas
BigJim I don't know if you can replicate that in model railroading. Then, what about dynamic braking???
That's one of the big selling points for the recent "Full Throttle" feature on ESU Loksound decoders. Pressing F9 (in DCC of course) allows you to hold the motor speed while ramping up, or down, the prime mover RPM.
I do like the effect as I can get my reain barely moving, press the F9, then turn up the throttle as if the engines are really working hard. Several more taps of F9 allow the train speed to catch up to the percieved prime mover speed.
The same effect can be had when your train is up to speed you can lower the throttle setting, reducing the prime mover RPM but keep the train moving along.
I like to simulate transition using this feature, too. Yes, dynamics can be simulated as well with cooling fan sounds and speed reduction while the diesel continues to run faster.
Some engines with head-end power (passenger) can be run at full diesel RPM while using the throttle for speed control only.
Cheers, Ed
That sounds like a lot of work! (pun intended)
BigJimThat sounds like a lot of work! (pun intended)
Yeah, there is that crossover between what you do for a living and what you do as recreation.
Nice thing about the FT feature is that it is strictly optional so you don't have to mess with it at all and other decoders have their versions of Dynamic Digital Exhaust and such which is supposed to detect when the motor is "loaded" and increase the exhaust sounds. All depends on what your goals and desires are.
Thank You, Ed
gmpullman, can you explian more about prototypical practices like the ones you described? My Scaletrains gevo does have a full throttle decoder, and I was always confused about f9. Also, my Econami decoder can do the same thing, although I don't know how many people know that. Honestly, the only major difference I have found between Tsunamis and Econamis is the amount of sounds available. Econamis have a lot to offer, and I want to use that too.
BNSF UP and others modelergmpullman, can you explian more about prototypical practices like the ones you described?
I'll defer that to Matt Herman:
My only Econami decoder is for an electric and I haven't done anything with "manual notching" since it mainly has blower sounds.
Some sound decoders override the prime mover using the manual notching functions, whichever button they're assigned to, so if you want the engine to sound like it's working, just notch up and vice-versa.
Good Luck, Ed