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Subject: 
Re: Tilting trains (Used to be: how did James Mathis make his tilting trains?)
Newsgroups: 
lugnet.trains
Date: 
Sun, 10 Feb 2002 03:20:25 GMT
Viewed: 
1093 times
  
In lugnet.trains, James Mathis writes:
No. Even in real-life trains, I'm not sure that making a train tilt through
a curve necessarily enables it to go any faster than it could if it didn't
tilt.  It is my understanding that tilting the train cars is more to keep
passengers more comfortable (and saucers on the table)-- orients the
perceived direction of gravity to remain closer to perpendicular to the floor.

I think that the maximum speed through curves is more based on the location
of the center of mass above the track and radius of the curve.  The speed,
center of mass, and radius of curve all determine the force (centripetal)
and consequent torque that acts to tip the train car over (derail) through
the curve.

Banking the track tilts a train, too, but it tips both the cars and the
wheels.  The result is higher speeds than if the track weren't banked.
Banking the track through curves permits both greater max speed and
passenger comfort, irrespective of whether the train cars tilt.  In banking
the track, the angle between the direction of the centripetal force and the
surface of the track is reduced.    This allows for greater speed through
the curve before the train would tip over.  Think NASCAR banked oval tracks.
I don't think that only tilting the train cars is the same thing.

I know this is a pretty inadequate explanation--maybe pretty wrong?

So, I don't think that tilting the brick-built train should necessarily
yield higher speeds through the curves.  Wish it did.  In fact, with the
brick-built train, I am wondering if the swinging motion actually tends to
throw the train off the track as it enters the curve. ??

later,
James Mathis

LECTURE LECTURE LECTURE LECTURE LECTURE LECTURE LECTURE LECTURE LECTURE

     I have a 'Ultimate Visual Dictionary' and it has a pair of pages about
tilting trains, though it only mentions the Pendolino and a 'French tilting
train' that it dosn't name.  Anyway, it describes the mechanics of the
tilting train.

     Whenever a train turns on a curve, a centrifugal force is created that
pushes the interior of the car to the outside of the curve (the obtuse part
of the curve)thus resuting in objects moving.  You feel that same feeling as
when a car turns.  This results in some passenger discomfort.

        \ \
         \ \
          \ \
          / /    __\
         / /         /
        / /        Centrifugal force
       / /

     Train tracks on curves are always banked to about 6 degrees. However,
on tilting trains, a hydraulic system on the truck frame(it would be the
bogie plate on Lego trains, I belive)pushes the car above it towards  the
acute angle of the curve(the opposite of the direction of the Centrifugal
force)at angle of about 8 degrees, thus compensating for about 70% of the
centrifugal force, increasing passengar comfort.




                  \ \
                   \ \
                    \ \
            /_      / /    __\
            \      / /          /
  Sideways / /        Centrifugal force
  force      / /
  produced by
  tilting.


      The total tilt of 14 degrees results with greeater comfort and safety.
ALSO the tilt allows speeds up to 30% higher then normal.

                     The end.

        John Henry Kruer



Message has 2 Replies:
  Re: Tilting trains (Used to be: how did James Mathis make his tilting trains?)
 
John: Thanks for quantifying that the "tilt allows speeds up to 30% higher then normal". Sounds like a good couple of pages of reading in that 'Ultimate Visual Dictionary'. later, James Mathis (...) (23 years ago, 10-Feb-02, to lugnet.trains)
  Re: Tilting trains (Used to be: how did James Mathis make his tilting trains?)
 
Some tilting train reading if you're interested: (URL) Mathis (23 years ago, 10-Feb-02, to lugnet.trains)

Message is in Reply To:
  Re: How did James Mathis make his tilting trains?
 
(...) No. Even in real-life trains, I'm not sure that making a train tilt through a curve necessarily enables it to go any faster than it could if it didn't tilt. It is my understanding that tilting the train cars is more to keep passengers more (...) (23 years ago, 9-Feb-02, to lugnet.trains)

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