Not in my experience

Moving from a stop without notching up happens when you release the brakes on a grade.

Yes, the prime mover is turning the generator/alternator at idle, but moving the throttle up is what changes the contactors in the electrical cabinet that direct that electricity to the motors, and in the correct direction.  Otherwise, how would control speed at idle?

Scott Chatfield, a civil engineer, not a locomotive engineer, but I have run real locomotives

Notch 1 is the same RPM as

Notch 1 is the same RPM as idle on some locomotives, so yes you can move the locomotive under its own propulsion without increasing RPM, allowing for grade, trailing tonnage, etc. The alternator affects the load on the prime mover so there is typically a difference in the sound of the engine idling/notch 1 without load and notch 1 under load. 

Idle vs Notch 1 and loco movement

Based on what I've heard from real Engineers, I think (but I'm not sure) some locos work like this:

In Idle there's no load on the prime mover. With the Independent Brake on and the Reverser Centered you can notch up the prime mover with no loco movement. Maybe to pump air with certain compressor types etc.

With the Independent Brake on, set the Reverser to forward or back, then select Notch 1. The Prime Mover revs don't rise, but now the traction motors are switched into circuit. This places a load on the alternator which in turn causes a "sound of load" from the Prime Mover and maybe a slight drop in revs.

Then if the loco is running light or with a short train, when you release the Independent Brake the locos will creep forward in Notch 1 before the throttle is moved up to Notch 2 etc.

I've tried to replicate that with ProtoThrottle and LS5 DCC decoders in my roster.  Here's a quick clip that shows the progression from Idle to Notch 1, "sound of load", then release the brake, locos creep forward as the train is very short, then Notch up further as required.

This process works on level track with light loads but on an up grade or with a longer train, I think you'd likely Notch up to 2 or 3 before releasing the brake.  

Pete (the endless tweaker) 

Oz railfan comes through

Thanks for those replies, gents.

I wanted to see what else I could find and eventually happened upon this nice video covering all three options. Some do start moving before the prime mover ramps up, some are the classic notching followed by moving, and some are basically simultaneous.

The ones that move away first don't get far before notching up a bit, but you can tell they are doing it.

American Locomotives

I was hoping some of our resident Professional Railroaders would speak up with real-world experience, but in their absence I did a very unscientific survey of youtube videos depicting American locomotives.  I was able to find a lot of videos of passing trains, but not as many of trains starting from rest.  Here are my observations -- not scientific or definitive, but what I saw while watching a couple of hours of videos:

Early EMDs (F7, GP9) appear to rev up before moving.

I found one EMD E8A, and it appeared to move before revving, but it had been upgraded to modern lighting standards, so who knows if the prime mover had been changed out or modified.

Later EMDs (SD-45 and GP-38-2 in particular) revved before moving -- and they seemed to have a rather high "idle" RPM.

Alco RS-3s and S-4s (and an RSD-18-or-something) moved before revving.

Modern GEs appear to rev before moving.  I wasn't able to find a good video of an older GE starting out, but from the lousy ones I found it *appears* they move before revving.

I couldn't find (and, I admit, I didn't look very hard) any Baldwins or other smaller locomotive manufacturers.

So, it seems that you'll need to program each decoder to mimic that prototype's behavior....rather like setting the correct prime mover and air horn. 

And hopefully one of the Pros will chime in with corrections and additions.

Situational difference?

I suspect North American Diesel Electric locos must work about the same overall for getting under way. After all the real RRs need "everything can be consisted with everything else" at least for road power.  It's easier for them also as their locos aren't direct drive like most of our models. 

So I suspect it's the specific situation that causes the differences. How you get under way with light engines or a small train on level track being very different from starting a long heavy train on an up or down grade or over undulating terrain. 

As well we're typically only able to model the equivalent of Independent brake action not the Train brake which must limit what we can replicate to some degree. 

Plus some passenger power runs in Notch 4 or 8 all the time for HEP so there must be a different trick to not spilling the coffee in that case. 

Here's a quick clip of the same power as my above light move, but trying to simulate starting a heavier train by notching up more before easing off the Independent Brake. I have no idea how prototypical this is so hopefully we'll hear from real world Engineers soon!

Pete   

Tsunami2 deadband, momentum, and brakes

It is true that it is not implemented out of the bag on the T2 but there are three features that can be used to allow a T2 to throttle up without moving, at least at first.

Deadband can imitate the Loksound decoder's method of waiting until the prime mover sound throttles up before moving. Implementing it can be found in the T2 technical reference - a document every Tsunami owner should download.

Momentum - this is actually in many decoders, and has been discussed frequently in association with the ProtoThrottle. The big question is generally "how much momentum?" But it does make for a potentially slow take off from stopped.

Brakes - the most aggravatingly wonderful feature of modern sound decoders. Wonderful because combined with momentum you can get something resembling prototypical control, aggravating because each decoder manufacturer implements it differently, effectively preventing a mixed decoder lash-up that would use the feature. But on the T2, if the brake is set when stopped, the locomotive isn't going to move until it is released.

And yes, all of these features would need to be set up, in part because they tend to be personal preference things in the way they work. 

Pete and Jeff

Pete,

Actually, " After all the real RRs need "everything can be consisted with everything else" at least for road power." doesn't apply...at least with older models.  There are many instances where certain classes of locomotive can't MU with others, for instance with different throttle mechanisms (Baldwin), and different air brake systems.  The Erie Lackawanna inherited locomotives with both 6-SL and 24-RL brake systems, which were not interoperable. 

Jeff,

The Tsu2 will rev up on speed step 1 unless you've turned on "True Idle" in CV 112 and CV 114.  I've standardized on SoundTraxx, and find that, in general, a moderate acceleration momentum setting of 6 (when not using brakes) will allow the prime mover to start revving before or just as the locomotive starts moving.  You could also use a speed table to set the voltage at the first couple of speed steps below that needed to move the loco.  On the other hand, when I have set the locomotive up for operation with brakes, I use a value of 20-25, depending on the loco service type (road vs yard). 

Starting delay in decoders - mixed blessing?

Jeff, all good points! And it's great  we have so many neat features to play with in our decoders these days.

I don't use the starting delay in my LS decoders because that prevents the "sound of load" and crawling in Notch one when lightly loaded effect of my first clip above.  For some reason I've become addicted to that effect.  Maybe I'm compensating for short-trains-only syndrome?   

Fortunately the PTs variable Independent Brake enables slow easing off against a higher Notch in the second clip when needed.

Pete

Why not read the manual?

Instead of guessing what a particular locomotive might do in notch 1, one can examine a scanned operating manual for the locomotive in question posted to the web. For example, in a GP9 manual available at the wplives site, EMD writes:

"Each running notch on the throttle increases the engine speed in 80 RPM increments from 275 RPM at idle and Run1, to 835 RPM at full throttle." (bold emphasis added)

The contactors close in notch 1 and the generator drives the traction motors. Therefore the default sound slot behavior programmed in ESU GP9 16-567 non turbo sound files is correct for a light GP9 on level track. In notch 1 with the brake off the engine should move. 

Regards,
Bob

No one decoder setup will be correct for all situations

A locomotive with a light load will move in the first notch with very little change in sound. On a down grade it could reach a very high speed with the throttle in idle. The dynamic brake or independent brake could be used to control the speed.

With a heavy train I would use the first notch to start stretching the slack. If notch one would not move the train I would go to notch two, three, or higher if needed. Usually once the train started to move I would reduce the throttle position to prevent the head end from picking up too much speed before the rear end moved, sometimes back to the first notch. Leaving the throttle in too high a position when starting results in a broken knuckle or drawhead or the conductor bouncing around the caboose.

After the entire train is moving the throttle is advanced gradually to reach the desired speed. The same basic procedure is used for lighter train but you can go through the steps more quickly.

Starting on a grade requires a different method. If the slack is stretched the throttle must be set to a position high enough to prevent the train from running backwards down the grade. After the train begins to move care must be used in advancing the throttle so as not to pull too hard which could cause a break in two.

If the train will not start when stretched on a grade with a reasonable amount of throttle the slack will have to be bunched up using the air brakes. The throttle will be handled somewhat like starting on a level track except that once the head end starts to move the throttle will not usually be reduced. The trick is to keep the train moving very slowly so that each car begins to move just as its brakes release until the rear end is moving. As the slack is taken out of the train the weight of another car must be pulled up grade and the throttle must be increased to avoid stalling. If the head end stalls the rear end may begin to move down grade as the brakes release causing a break in two. At the very least you will have to bunch up the slack and try again.

Some locomotives have a system called Power Reduction. When this is turned on the throttle can be set in any position and the amperage controlled with a rheostat just like on a model power pack or dcc throttle. This in effect gives an infinitely variable throttle which allows much finer control in critical situations than the eight notches allow.

On a four car commuter train I would start in the first notch to stretch what little slack was in the train and then go right to notch five. At 10 mph I would go to notch eight until up to speed and then vary the throttle to maintain the desired speed. Some engineers would go right to the eighth notch when starting but  that would cause the engine to slip and the slack to run in and out making for a rough ride in the coaches and on the engine.

Because of all the variations in train handling I don't think any of the automatic notching schemes are very realistic. The manual notching can be much better if you know what you are trying to simulate.

Mark Vinski

Moving without notching up

Decoders that won't allow a locomotive to move without starting the diesel engine are not 100 % accurate.

Some locomotives are equipped with Spotter Circuit meant to be used in a service area so locos can be moved short distances without starting the diesel engine.

When working a yard job the engine would be parked out of the way on a side track with a slight down grade with the diesel engine shut down while taking a lunch break. On occasion we would have to move it to allow some other move before we were ready to go back to work.

I would tell the yard foreman to line the switch and I would drift the loco out of the way and after the other movement cleared I would drift our loco back upgrade into the side track all without starting the diesel.

Nobody ever questioned how the loco could drift uphill.

Mark Vinski

Spotter circuit

Mark, I’m curious about the spotter circuit - what was the power source?

Thanks Mark!

Thank you for taking the time to write all that up for us Mark.  Exactly what I was hoping for, and hopefully useful for the OP.   

I echo Ken's question - do tell!   

Pete

Plus One, or two

Thanks Mark and Ryan for additional insights on how this all happens at one to one scale.

It really makes the modelling more interesting to know these things. It makes it come alive, so to speak, and it's fun to try and match it.

Spotter Circuit Power

The spotter circuit uses power from the batteries.

Mark