I am in the process of putting together a basic test plan for my N scale engines. This is similar to a process that I have used with HO for years. I am noticing that my first couple of engines are showing a very steep velocity voltage curve. A new Kato engine measures 220 SMPH at 12 volts. It runs 100 SMPH at 6 volts. I have examined a few others at this point. The are all showing very high speeds at 12 volts. Should I be surprised by this? Are the She models normally run at half power & below? Thanks, Larry
Scale speed vs layout speed I just run my trains at what *seems* to be right for the size of the layout and type of train. My shinkasen travel faster than my fright / passenger which travel faster than my switching. I imagine that with DCC you will get different results. Edit: typo
I run freight at a top speed of 30 NSMPH, passenger is pemitted 40 NSMPH. Switchers in the port are held to 10 mph.
Unwritten law in N scale modeling; Do not exceed warp 8 or else the space time continuum will be disrupted. But actually Kato engines run fast. Atlas did also until they went with a "scale speed motor" LifeLike locos run slower than Kato or Atlas. I can't speak for other loco makers. So if you want to speed match a Kato and an Atlas in a consist then you will need DCC.
This issue is typical and was worth a note in every N Scale locomotive review at Model Railroader for decades, on and on and on. It always puzzled me, as the solution was to simply not use the entire radius of the throttle knob. It made it difficult to mu locomotives of different makes, but I never did that anyway. Larry, you may want to sample an Atlas locomotive with their most recent Scale Speed motors. They're most impressive in their ability to run slowly, perhaps almost too good.
So what speed step or voltage are you running? Part of my testing is to define how much train the engine will pull. That is tricky. I define a nominal weight car. The I weight cars so the have up to seven cars worth of weight. This allows me to examine up to 50 cars on my 6.5 foot test section. The speed degradation as the train length is increased is a result. The details will be in another post. I am surprised at the high speeds I am seeing. A nominal train load, for a 4 axle diesel that is 8 cars, only impacts the speed be about 5 percent on a level surface. I did some detail work on a used Trix F7A. As received it ran 140 SMPH at 12 volts. Still on the high side. My experience with HO indicated that a reasonable reference voltage for my tests was 12 volts. The BR level is 14.1 with roughly 2 volts loss in the electronics. HO max voltage is stated to be 16 volts. Actually tends to be higher from most supplies. In N scale the “max” is 12 volts. What I’m looking for is a good reference voltage for these tests in N scale. Of course the details of the engine performance have an impact on that selection, thus the reason for the original question. Thanks, Larry
I use DCC exclusively. I have a calibrated speedometer so I created several classes of locomotives and gave them all the same speed table settings and then sent them all along an oval and used the trim features to dial in the top speeds. So all my SD-80's or SD-40's Geeps and all the rest can run together with the other locomotives that would normally be in that class. Just no S2's running with modern Amtrak Passenger locomotives.
One thing the Bachmann got right was the speeds on their 44 and 70 tonners, Full speed on them is about one third on what you will find on other brands. And no matter far for you push the throttle they do not go any faster.
Hardcoaler, I am interested in the “scale speed motor” comment. Your the second responder to reference that. I still do a lot of testing in HO arena. This year the focus has been on motors. Examining the impact of torque & motor speed rpm on train parameters. Low speed performance is dominated by the motor torque capacity that is delivered to the drive shaft. The pulling capacity is dominated by the rpm delivered to the shaft. In general the higher the better within reason. The highest torque motors tend to have lower rpm’s. By adding an inline gear box, one could trade some torque for rpm. That could give you a better match of engine speed at the high power side and maintain exceptionally low speed capability. One could refer to that combination as a scale speed motor. I have various manufacture engines at hand, I am not sure if I have an Atlas. What models have this motor technology? Thanks, Larry
DCESharkman, What speed are you setting for max on your mainline engines? DCC allows you to do this. For various reasons I am looking at the details, every piece helps. Thanks, Larry
I'm not sure. Perhaps other members might know. I've never analyzed locomotive performance with any sort of data collection. My primary interest in locomotives is smoothness of locomotive operation without sputtering, stalling or distracting noises. If a heavy train needs more power, I just add an additional unit.
I measured the speed of my five DCC-equipped N-scale steamers on a measured (5 feet = 800 scale feet) stretch of straight and NEARLY level (~0.25% downgrade) track at multiple DCC speed steps (in increments of 10 steps, from 10 to 90; the results were surprisingly linear). I used these measurements and excel to set up three-point speed tables for each loco such the the loco speed in scale miles per hour equals (within reasonable variability across the range from 0 - 50 smph) one-half the speed step setting on the throttle. For example, a throttle setting of 20 gives 10 smph, 40 = 20 smph, 60 = 30 smph, etc, on the straight and "level." The top speeds I run then vary with loco and situation: everything at 10 smph or less in yards, smaller locos (4-6-0s and 2-8-0) max at 25-30 smph out on the road, and my FEF-3 and Challenger up to 45-50 smph out on the road. I also set my decoders to phase out B-EMF speed control at the locos "road speed." This causes a loco pulling a heavy train to slow down as it starts up my layouts 2% grades, and speed up slightly as it heads back down grade.
Larry, I certainly agree with everything stated above this post but IMHO the "scale speed" motor is nothing more than marketing hype. Yes, I have heard all the "KATO's run too fast" comments and in my 70+ years of playing with all scales I learned that the throttle does not have to go wide open all the time. Off my soap box.... I am dcc only and the club I belong to is totally dcc with Digitrax. I will admit that using dcc is very easy to "speed match" all manufacturers regardless of the motor used. You asked David about about mainline loco speeds. I know you did not ask me but here is what I do. First an image of a form that I use in a matching session : You can see the different CV settings between the FVM & KATO units and you can see one KATO is quite different than the other KATOs. I set all my diesels at these same settings. I have found, at times, that I had difficulty pulling a train up the 2%, reverse s curve but I just added another loco and ended the problem. I know you did not mention speed matching but it is worthwhile. Here is a short (4 minute) Y-T video of the locos on the above chart at work. All of these units were running ! BTW, I use JMRI for this purpose. Sorry 'bout rambling ,be well, Carl
Thanks Carl. I’ll looking for all the prior knowledge I can get. In those charts, are those speeds measured or calculated in any way? I assume they are & you have varied the CV value’s to achieve the desired value. The end values of speed are basically the same. The CV values to achieve them are different. Interesting input. Thanks, Larry
I believe the scale speed motors came after the initial introduction of the SD35's in the year 2000. The model was re-run in 2005 with the scale speed motor. In 2001 Atlas released the GP38 with thee scale speed motor. I believe this was the first model to come equipped as such.
High speed motors get in the way when you are trying to run at crawl speed in DC; even the tiniest touch on the throttle can make a huge difference. I do wish they'd set the gearing differently but my guess is that gearing works well on Shinkansen and AGV locos. The plan I follow (not sure it's the best) for setting speeds on my US freights is to look up the loco prototype's max speed in Wiki or somewhere, then set the max-speed CV so that when I hook it up to 10 cars and time it on a measured track it hits that speed at full throttle. I set the mid-speed CV to a quarter of that to get fine control at low speeds. May not be the best plan if you want to speed match different models, but max speed on prototypes seem to be pretty similar.
Larry, By no means am I suggesting that my way is the best, far from it I'm sure. Yes, I use an Accutrack speedometer set on N scale. I also tow an Aztec rail polisher behind each loco while speed setting. That is to give a small drag on the unit being set as well as keeping the rails polished. I set alll my mainline diesels to the same speeds. I probably should kick up the max to 75 - 80mph ? ? Be well, Carl
