SOME THOUGHTS ON SPEED

Discussion in 'Running Your Trains' started by class48nswfan, Oct 1, 2018.

  1. class48nswfan

    class48nswfan Full Member

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    There is nothing more I like than setting the controller, sitting back, picking up a mug or glass of something appropriate and spending time watching a train make its way steadily around my Wallace Creek layout. On the real railway however trains don’t run with a constant speed and yet at exhibitions one occasionally sees trains running at inappropriate speeds which would result in the driver having to answer some uncomfortable questions if he or she were out on the main line. Not that Wallace Creek is immune to this as a number of my older locomotives (Lima especially) do not respond as well to the controllers as well as newer Powerline, Auscision and Austrains models.

    There are a number of factors to consider with speed and how you operate the railway. I should add this is written from my experience with a DC layout and DCC may offer different opportunities. Firstly there is the track speed which can vary between two points. In the UK these can be found in the Network Rail Sectional Appendices (available online). If you find a table A in one of these you will see the line speeds detailed for all the main lines in the UK. Every pair of points has a line speed and that is directly related to the length of the points and the accompanying line speed.

    At Mowarra Junction I have a main through platform line and a loop and the points at the end of the loop are actually quite short. So whilst a through freight to the fiddle yard might run at a reasonable speed though the platform road, I slow any trains routed via the loop for these points. On plain line track there is no reason why you cannot have a Permanent or Temporary Speed Restriction (PSR/TSR) on the route perhaps to reflect altered track conditions in the locality. A rickety bridge may be another excuse to slow down and a recent trip between Peterborough and Ely saw us slow where that line crosses the New Bedford River (Hundred Foot Drain).

    Locomotive acceleration and speed is another factor that needs to be considered. A freight train will accelerate more slowly that a passenger train and when passing two fixed points, and this assumes there is a line speed for passenger services that is above the typical 75mph top speed for a UK freight. Of course unless you have a four-track main line with Fast and Slow lines with trains running alongside each other this is probably imperceptible to the casual observer. Freight trains in the UK generally run as Class 4 (75mph), Class 6 (60mph) or Class 7 (50mph) these days but Class 8 and Class 9 did exist in the not so distant past. In fact whilst researching this article I have found different definitions as time has passed.

    However here in model railway world, I would suggest something a little simpler remembering that track speed trumps train speed.

    High Speed Passenger

    Passenger

    Fast freight (generally containers)

    Medium freight (generally more modern bogied rolling stock)

    Slow freight (older 4-wheel rolling stock)

    Then we come to braking and once again I have to confess I don’t always live by my own rule book and the anchors are sometimes applied too late and the trains stops on the proverbial sixpence. The correct way to do it is gentle deceleration to a gentle stop as best you can.

    Whilst running on the main line can over encourage high speeds, shunting around the sidings at Wallace Creek means the opposite in that I operate trains at crawling pace. If you watch a diesel shunter in action (not that easy these days) they generally have an application of power then coast for a while with perhaps a bit more power before starting the braking to the stop point (be it buffer stops, signal or another vehicle). I have tried this and in my humble DC set up it’s not easy to replicate satisfactorily and I tend to shunt at constant low speeds (although I have seen a UK model with a certain type of gearing which meant you had to drive it like that – and if anyone can add anything about what this was called I will be grateful ).

    Perhaps one of our DCC brethren can enlighten us as to whether that system offers better options for managing line speed?
     
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  2. Toto

    Toto Staff Member Founder Administrator

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    Must admit, I'm not the most knowledgeable on prototype characteristics but I like to see the model world moving at slower speeds as I like the chance to view them properly and admire the models.

    I did have a class 33 with wings once though. :avatar: That's another story.

    Toto
     
  3. class48nswfan

    class48nswfan Full Member

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    Well having enticed us with that titbit I think you should at least share it!
     
  4. Toto

    Toto Staff Member Founder Administrator

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    On my original layout build The R&GLR I had the sub level which was a fiddle yard level built. I also had a ramp that rose up to take loco's to the upper level which was still under construction. Can you guess yet. .......... I was testing out the track on the ramp to ensure the bends were ok and all was good and got a bit carried away with the speed. I went to slow down to stop the loco before the end of the ramp which exited into fresh air but unfortunately the momentum setting was not set correctly. I ended up having to toss the controller and launch myself across the shed in an attempt to catch the flying loco, my class 33 ( Glenfallon ). I now ( as far as my memory let's me ) make a point of knowing how the momentum is set on my handsets. :avatar:
     
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  5. class48nswfan

    class48nswfan Full Member

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    I assume you managed to catch the errant 33? Perhaps renaming it to Icarus may have been (be?) appropriate?:avatar:

    Dave
     
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  6. Andy_Sollis

    Andy_Sollis Full Member

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    Some DCC controllers will use feedback (or should that be the decoders) which in my thoughts would be the opposite of the real world as coming to a hill, would slow you down unless you increase the throttle.

    My biggest bug bear with working on the real thing that I see with modellers is how quick a loco stops and reverses? Or shunting... I know some folk work to compressed time scales, but if you were to really think about the fact that you have a brake pipe to split (if fitted, either air or vac) unscrew or even loosen the coupling (by squeezing up couplings, not something we can easily replicate due to a lack of wheel chocks or handbrakes in 7 or 4mm.) shunted then crawling out to send the loco or train the opposite way. Even a loco on its own can’t just stop and reverse. You often have to wait the brakes to come off, which is sometimes replicated with the DCC sound chips as diesels sometimes delay starting when you open the throttle before the “psss” of the brakes come off. Sound the horn, glide away...

    Just my thought.
     
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  7. class48nswfan

    class48nswfan Full Member

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    If I reverse an engine whilst shunting I generally count to 10 before the reverse move starts (even when operating solo). Model railway time does not have to be the same as actual railway time especially if you are at a show where the (not necessarily informed) audience like to see something happening but its certainly worth taking that time. It may also be the time it takes for the new signalled route to be set.
     
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