I've often read and seen the term used but still not sure what it means
I'm a digitrax user and my throttles are UT-4s and a Zephyr comand station
but none of those Display Speed Steps
Is this just a Decoder Pro term ?
TIA
TerryinTexas
See my Web Site Here
http://conewriversubdivision.yolasite.com/
Speed steps are discrete increases in voltage to the motors, courtesy of the decoder's drive output. I believe in some instances they can be as few as 14, but most of us use a combination of 28/128 speed steps.
On my DT400 throttles, with the encoder knobs set to chirp with each detent engagement, I can dial in one single speed step increase, say from 11 - 12, and I can actually hear the change in pitch in the various engine models almost immediately. I use 128 speed steps, but still to this (cough...) day, I have not entered the tables to modify any of my engines. They work fine for me because I don't consist any of them. I don't really have enough engines to pair up, say, Y6b's or PRR J1's.
Maybe some day.
-Crandell
C&O FanIs this just a Decoder Pro term ?
Terry,
Speed steps are the incremental settings that the throttle/decoder is set to as the locomotive increases or decreases in speed. It can be set to either 14, 28, 128. (14 was the standard on older decoders. 28/128 is general the default now with the new decoders.)
14 is the most course setting; 128 is the most subtle. 14 speed steps takes you from 0 to maximum velocity in 14 clicks of the speed knob or button; 128 speed steps, 128 clicks of the speed knob or button. As you might surmise, the changes in speed at 14 will be much more abrupt between each speed step than at 28 or 128.
I have a Power Cab and it does display speed steps, which I like. I'm sorta surprised that the speed step is not displayed on your Digitrax throttle. Is it a setting change maybe?
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
tstage C&O FanIs this just a Decoder Pro term ? Terry, Snip I have a Power Cab and it does display speed steps, which I like. I'm sorta surprised that the speed step is not displayed on your Digitrax throttle. Is it a setting change maybe? Tom
Snip
Tom
No the UT-4 Throttles are just a plain box with no display screen
http://www.digitrax.com/prd_ut4.php
The only thing that the Zephyr displays is the loco # you are operating
I guess speed steps only are displayed on the more expensive throttles like Crandells
But I wasn't aware they chirped ! That's pretty Cool !
C&O FanNo the UT-4 Throttles are just a plain box with no display screen
Of course. Terry, is it the DT400 throttles that only have the display?
tstage C&O FanNo the UT-4 Throttles are just a plain box with no display screen Of course. Terry, is it the DT400 throttles that only have the display? Tom
I don't know ask Crandell he's the one with all the money
C&O Fantstage C&O FanNo the UT-4 Throttles are just a plain box with no display screen Of course. Terry, is it the DT400 throttles that only have the display? Tom I don't know ask Crandell he's the one with all the money
DT100, DT200, DT300, and DT400 all have displays. The UT-4 is a simple cab, comparable to the CAB-04P in the NCE line.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Thanks, Randy.
MILW-RODRLets look at this in a prototypical fashion. All prototype motive power uses an 8 notch throttle, or seen as 8 speed steps. Now of course in prototypes the notches are set to a certain engine rpm rather than train speed but it makes less sense explaining it that way.
I've run full scale trolleys at RR Museums, which do run slightly different than Diesel-electric, but... While each each power notch does establish a maximum speed, the series motors act LOTS different than the PM motors in models. Each notch establishes an acceleration curve, with the tractive effort roughly inverse to the speed. Maximum speed is called "Balancing Speed" because the T.E. is exactly the same as the drag at that speed. If the load or grade changes, the balancing speed changes. When you are trying to maintain a speed that is not a balancing speed for a notch, you are constantly changing the throttle.
For electric prototype, you have the additional complication that most notches are not "running notches" -- they are acceleration notches with resistors that will burn up if you stay in that notch. Most electrics have series/parallel controllers with two running notches -- Full Series (roughly half speed) and Full Parallel (max speed). To run slower, you coast when you are too fast, then notch up to Full Series or Parallel. The notching up process is another complication of electric prototype.
Permanent Magnet motors have a speed that is almost exactly proportional to the voltage and don't behave like the prototype with series motors. This is good because we can control the speed directly. AC prototypes have computer programming so they behave similar to DC prototypes with series motors.
Take the maximum speed of your locomotive in scale MPH, and divide it by 14. That's how many MPH your engine speeds up each speed step. If your engine's top speed is 100 MPH, each speed step will be about 7 MPH, so if you're going 21 MPH the next increase would jump you up to 28 MPH. If you have 28 steps, it will only go up about 3-4 MPH per step. If you have 128 steps, each step will be less than 1 MPH, giving you much smoother control of your engine.
wjstix Take the maximum speed of your locomotive in scale MPH, and divide it by 14. That's how many MPH your engine speeds up each speed step. If your engine's top speed is 100 MPH, each speed step will be about 7 MPH, so if you're going 21 MPH the next increase would jump you up to 28 MPH. If you have 28 steps, it will only go up about 3-4 MPH per step. If you have 128 steps, each step will be less than 1 MPH, giving you much smoother control of your engine.
I suspect, though I have never tried to proved it, that things are much less linear than that. Nonetheless, the general idea is the same.
I don't think trying to relate controlling our models to controlling the prototype (throttle wise) is a very good plan. Things just don't really scale that way.
Jeff But it's a dry heat!
The voltage output from the decoder is linear - however the motor may not respond in a perfectly linear fashion. This is why we have start/mid/max settings and speed curves - you can tune whatever response you want. Passenger locos, you might want to ge tup adn go quickly, so the 'curve' would rise fast then level off. Freight engines, just the opposite - shallow gradual rise until the mid point then a steeper rise to top speed. Switchers - shallow rising curve across the board with a low top end. By limiting the top speed you increase the amount of control you have over the loco sicne the same number of speed steps is divided over a smaller overall change of the decoder output.
Then there's momentum, which cna doa lot to hide the coarseness of the 14 speed step mode. Sure each step might be a 7 smph change in loco speed, but with momentum enabled that can take 30 seconds or a minute to actually change that amount.
I'll stick with 128 SS, I prefer the fine control, especially when switching. This is also why I prefer the fancy throttles with encoders - a potentiometer only has a limited rotational range, maybe 270-320 degrees. The encoders can take 2-3 full turns to cover the entire speed range - but they are also ballistic so a quick spin can jump the speed up or down rapidly - like when the Limited is about to hit an open drawbridge (liftout section) - you don't have to turn the knob 2-3 times to bring it to a stop, one quick partial turn will drop the speed to 0 even if it took you 2 turns to ge tup to speed as you realistically pulled out of the station.
Course the UT-4 has a "center off" direction switch, so you can just 'hit the brakes' that way rather than turning the knob down. However how quickly the engine slows down from that point is determined by the momentum settings, the UT-4 doesn't have a "panic button" that shuts track power off.
I know that QSI decoders have a real brake application when F7 is pressed, bringing the engine to a quick screeching halt over about 3-6 seconds, regardless of the momentum setting in CV4. Are there other decoders that offer this sometimes handy feature?
I don't like pressing the emergency button on my DT400's because if the engine is moving a scale 60 mph, that application makes the active engine stop immediately, and I worry about the stresses on the shafts with a rotating mass such as a flywheel. So, if I see an increasingly urgent need to bring a passenger train to a fairly quick stop, but there is time, I use F7 with my BLI steamers, Atlas FM Trainmaster, one P2K SW8, and the Lionel Challenger. I can always resort to the emergency button if it looks like a collision will take place anyway, but by then the engine is slowed greatly, with the commensurate reduction in rotation speed of the flywheel.
I don't think you have to worry about the e-stop damaging the loco - that's what the flywheel is for. E-stop just cuts power, it doesn't apply a 'brake' to the motor, so the drivetrain will coast on the flywheel's energy. A greater danger is that the cars the loco is pulling will pile up behind it when the loco suddenly stops - maybe not a huge deal on a tabletop type of benchwork but if it happens on some narrow section or over some spline roadbed with scenery not yet installed, it's a long way down to the floor.