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Subject: 
Re: Reversing Loop without Insulated Tracks
Newsgroups: 
lugnet.trains
Date: 
Wed, 11 Aug 2004 07:05:36 GMT
Viewed: 
1707 times
  
In lugnet.trains, Larry Pieniazek wrote:
I suggest you read up on reversing loops for some background. There are
plenty of references out there if you use Google to look. But, failing that,
and also for the benefit of the rest of the readership...

Eh, I'm more interested in the electrical puzzle than the trains running on it.
Besides, I was considering the possibility that a motor might be set up with two
input leads and two output leads that would cause skipped poles if only one pair
of wheels were under power (seemed like a stupid thing to design into a train
motor, but I've wired up enough motors, including a few with variable phase
hookups, that I couldn't discount the possibility)

Consider an ordinary reversing loop without the extra switch, first.

<snipped for brevity>

Okay, so if you just put in a single point with a reversing loop, the two rails
on the straight line are cross-linked around the loop (I remember someone
telling me that a while back, but it's been a few years, and as I said before,
IANATH).  And adding the B point breaks that power link, except during the
(hopefully) brief period when the motor bogey is pushing its way through,
causing the switching rail (which is hooked up to the bottom rail on the
straight line) to bump the straight rail on the point (which is hooked up to the
top rail on the straight line).


Well, if I understand the way the points work correctly, I see two possible
solutions.  One is "foolproof", but the other requires a motor bogey in the last
car, so I'll explain the first one.  Okay, in Track Designer, lay out the
following track sections:

straight, straight, branch left (A point), curve right, join left (D point), 4x
curve right, 12x curve left, straight, curve left, join right (C point), curve
right, join left (B point), curve left

Set everything to straight except D.  The train will pass through A and D and
stall out on C, but it won't short out because B still acts as an insulator.
Turn off the regulator, switch everything but C (you can switch it if you like,
but it's not necessary, and it's safer if you don't), and then turn on the
regulator.  Any remaining cars will push through C, and then the train will pass
through B and A normally.  After it has cleared A, you can switch A, B, and D
back, while C acts as an insulator between the two main line rails.  This
arrangement uses the same track as the original, but adds two curved sections,
and two points of the same type that you used for B (you'll probably want to
mirror this loop on the other end so you use matching pairs of points between
the two loops), plus whatever additional track you need to add to give you
enough clearance between B and C for the last motor bogey to clear C without any
part of the train hitting B and forcing the switching rail over.

The other idea cuts out the C point, but it requires that the last bogey on any
train be a motor bogey, so the entire train can clear the D point before the
train stalls out, at which point you cut the power, switch all the points, turn
the power back on, and then switch them back (making sure you switch B before
D).



Message has 1 Reply:
  Re: Reversing Loop without Insulated Tracks
 
(...) Many of us are more interested in the trains running (remember that the name of the group, after all, is not lugnet.electrical). The electrical stuff is just a way to get trains to do their thing, in my view and hence, less interesting. Others (...) (20 years ago, 11-Aug-04, to lugnet.trains)

Message is in Reply To:
  Re: Reversing Loop without Insulated Tracks
 
(...) I suggest you read up on reversing loops for some background. There are plenty of references out there if you use Google to look. But, failing that, and also for the benefit of the rest of the readership... Consider an ordinary reversing loop (...) (20 years ago, 11-Aug-04, to lugnet.trains, FTX)

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