From: scott a smiley <sc.smiley@juno.com>
To: ttat-members@aoot.com
Sent: Sunday, June 7, 2009 10:32:55 PM
Subject: Re: Lift out bridge
Input from all will help vet issues. Ira make good points that need to
be addressed. One word of caution to all: Email does not convey
emotion, do not read any into it. The dialog is to be constructive, make
comments that way, and take them as such.
One help I think will be that when the bridge is closed, the pulling and
pushing we do in set up can be transferred through the closed bridge.
But then is the bridge serving its intended purpose? WE will also need
to think of the sequence of set up to see if it makes a difference with a
bridge.
One scenario would be start at the bridge unit with it closed, therefore
it would react similar to any other module if it has shear pins in the
joint.
Next would be a corner module close by so the power could be connected
for testing ( but then again we do not require a corner for testing any
more) so there should not be a
problem.
Once we get around the corners from the bridge, the layout would have
created some of its own stability and the bridge could be opened until we
get tot he last modules where we move a whole row around. Then close
the bridge for the last connections.
Once all locked down, the bridge would be able to be reopened as needed
for access to the layout interior. The unit would need some strength to
support the residual stresses in the modules, the opening forces, the
over turning forces and others we do not envision as of yet.
Actually, it does not seem that it will need to be exceeding string as
long as it is closed during the times when things are moving around which
is also the time when there are other ways into the interior. Since we
are working with a 4' section, there could be some gussets on the corners
on the floor to increase the strength of the joint
there. If we could
have a gusset system, then the joints could be pins so the parts could be
easily disassemble and likely fit into empty slots in the trailer.
I think the bridge unit will need to have some fail safe power control
system that would prevent a train from going across an open bridge. It
would be good if this was not the entire layout so if we get used to it
and can quickly open and close it, we might be able to allow some use
during run times and maybe only stop close by trains while others on the
far side would be able to continue.. This would likely need some wiring
outside of the module itself. Let's hear some ideas on this.
I have some/several AC relays that come in useful for this electric work.
They can handle track power.
Scott
On Fri, 05 Jun 2009 22:21:43 -0500 "Ira Schneider"
<
ira_schneider@Iname.com> writes:
> As Bill said, we have been discussing the possibility of building
> some sort
> of entry way to the layout for years. I would hate to see us rush
> into implementing
> something just because several people are "gung-ho" on doing
> something now.
>
> If we are going to build something, we need to completely understand
> the
> implications, both structural and practical.
>
> For example, the way we assemble our layout there are high shear
> forces
> on the modules. With a rectangular layout, there is no problem.
> However,
> with an L-shaped layout, there is a gap of 2-1/4" (in both
> directions) in the
> layout. We are able to force this gap closed by man-handling the
> modules.
> At the last show, the gap appeared to be
larger, probably due to the
> way
> we assembled the layout. With our current straight modules, there
> is
> no weak point in a module. With a bridge, we need to find some way
> to
> keep the module intact, even though there can be no structural
> member
> crossing the gap at track level. The only structural member would
> be
> at floor level, which may not be able to hold the tracks together
> properly.
>
> We also need to decide how and when this bridge could be operated.
> I have seen suggestions that the bridge would only be opened during
> setup and teardown. If this is so, is it really worth the effort?
> We
> normally leave a gap in the layout until we finish assembling the
> modules,
> leaving a space for people to move in and out of the layout. If we
> will
> open the bridge
while running the layout, how will this affect
> operations?
> We have four operators running trains simultaneously. They all
> have
> to stop their trains when the bridge is open. Is this something we
> really want to do during a show? If so, how often will this be
> allowed?
>
> Another thing to consider is how this module will be stored in the
> trailer.
> As Bill pointed out, the trailer is currently pretty well packed
> with
> equipment.
>
> I don't object to the concept of designing a bridge module, as long
> as
> all factors are considered. I just don't want to see us rush into
> implementing
> something without completely understanding all implications. And,
> yes,
> I am comparing this to the 45 degree corners. We discussed them
> for
> several years, then suddenly
rushed into implementing them without
> fully understanding the implications, including the fact that we
> need a
> much larger space for the layout when using the new corner modules
> and
> that they take up more space in our already packed trailer. Also,
> we
> currently have only two pairs of the 45 degree modules. Even
> though
> they look nice, they don't provide any improvement in operating
> large
> trains since we still have to use at least two of the older corners,
> which
> have smaller radii tracks. Also, using a pair of the new corners
> for the
> inside corner of an L-shaped layout didn't completely solve the
> problem
> of track 1 being the inside (i.e. smallest radius) track since we
> still
> have collisions between trains on tracks 1 and 2. In my opinion,
> the
> design for these
modules was rushed into the implementation phase
> without fully considering how they would perform in our layout.
> I don't want to see the same thing happen with a bridge module.
>
>
> Ira
>
>
>
>
> ------
> TTAT members reflector.
>
>
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