Train Length Button

Discussion in 'Traction & Rolling Stock' started by WannabeTrainDriver, 11 Sep 2019.

  1. WannabeTrainDriver

    WannabeTrainDriver Member

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    How does the loco know when the rear of the train has passed the point that the driver pressed the button? Is it something that drivers use frequently? Thanks.
     
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  3. Thedispatcher

    Thedispatcher Member

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    Pressed what button? Don’t understand the question here.
     
  4. Nym

    Nym Established Member

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    You program the length in and it measures distance travelled.
     
  5. Darandio

    Darandio Established Member

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    The Train Length Button, it's the thread title.
     
  6. Thedispatcher

    Thedispatcher Member

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    I don’t drive locos, I’m terribly sorry.
     
  7. Tom Maddox

    Tom Maddox Member

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    Always wondered this myself. Interesting to learn. Are trains measured in feet or metres?
     
  8. WannabeTrainDriver

    WannabeTrainDriver Member

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    Sorry question was very poor. On certain locos there is a train length button that can be pressed by the driver at for example the start of a speed limit... It will then play an audible warning when the rear of the train has passed that same point allowing them to increase their speed. Just curious as to how it works. GPS? Train length programmed in somewhere?
     
  9. hwl

    hwl Established Member

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    Several systems available, length is programmed in before starting (often in feet as they are US systems) and there is also a countdown read out on screen. Most locos have 2 speed measurement methods these days (wheel rotation and ground speed radar) but not sure which is used.
     
  10. 800002

    800002 Member

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    I recall a conversation with someone about this a while ago - concerning freight services.
    Without having any personal knowledge, there would possibly be two ways:
    1 - the driver knows the length, in feet / SLU's (whichever) and the unit reads off its calibrated measurement thus the driver knows when he's passed the point of activation.
    2 - the train length is input into the device and is squaks off an audible signal when the programmed length has elapsed.
     
  11. EE Andy b1

    EE Andy b1 Member

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    Yes a Train Length Button is correct. The driver enters the train length off the TOPS sheet, train consist, I think 5-10% is automatically added for the total length.
    When the driver reaches the termination of a specific speed to be able to accelerate, they press the button, it counts down in feet and bleeps once the rear of the freight train is clear.
     
  12. WannabeTrainDriver

    WannabeTrainDriver Member

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    Where is the information from the Tops sheet entered? On newer locos I would assume train management screens but on something older like a Class 57? Thanks.
     
  13. ComUtoR

    ComUtoR Established Member

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    I've always wanted one of those !! I never knew they existed and thought I had invented something in my head.
     
  14. 37057

    37057 Member

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    Trains have ways of measuring distance, one method being a toothed wheel on the end of an axle and a speed probe. A set quantity of pulses from the speed probe will determine a certain distance (20 meters for example). I've never worked on this system but I would imagine this would feed a logic controller that can be calibrated (train length) by the driver at the start of the journey and when set will sound an audible tone when the distance travelled matches that of the calibrated figure. Happy to be corrected if anyone knows for sure.
     
  15. EE Andy b1

    EE Andy b1 Member

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    If i remember rightly it was entered via the Q-tron black box system and the display and keypad in the cab. Not all locomotives have a Train length button.
    This was back in my EWS days.
     
  16. WannabeTrainDriver

    WannabeTrainDriver Member

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    Thanks for all the responses. Satisfied my curiosity.
     
  17. ExRes

    ExRes Established Member

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    Just how I remember it as well, when I did my 66 brake handling I did a couple of days on the Corby car train, being used to mail trains I remember distinctly coming out onto the MML and looking back to see the end of the train over the points only to see (some of) 2600 feet behind me, oh how my instructor chuckled :oops:
     

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