Removable roll away bridge between layout sections... Maybe a Double Helix..

[Mark W]

How about using a few linear actuators and extend a telescoping bridge straight out from a compartment just below the subroadbed.   Program this all to work with Arduino off the push of a button. 

[Ed Kapuscinski]

How about you keep it simple and build something you'll actually get to run?

[learmoia]

Hmmmmmmmmmm....   I wonder.....

 

[learmoia]

Initial tests produced mixed results..

Skip to 1 Minute in..

~Ian

[nkalanaga]

Complicated?  Mine would have two moveable joints, and both would be simple hinges.


On the right side, there's no need for both stops.  Either the bar on the bridge, or the shelf under the benchwork, will do the job.

[learmoia]

Complicated?  Mine would have two moveable joints, and both would be simple hinges.


On the right side, there's no need for both stops.  Either the bar on the bridge, or the shelf under the benchwork, will do the job.

Ceiling height 96" - layout height 50" = 44"  vertical clerance for a draw bridge.. 88" for a double drawbridge..  I need to span 120"..  (although the 2nd section could go to the floor)... so in theory, it could work..

[nkalanaga]

Two different lengths was my idea.  Stop the fixed end short of the ceiling, to allow room for the extended stops on the outer end, and allow the outer end to drop almost to the floor.  Putting a shelf on the far benchwork, instead of a stop on the far end of the outer section, will allow a few extra inches, because the bridge and track won't have to be cut short to allow for the stops.  Doing that, you should be able to get 40 inches for the fixed section, and 84 for the outer section, with a 4 inch stop bar between them, and the outer end just touching the floor.  Cut it an inch short and you'll still have more than the 120 inches you need.

Doing this may require some type of retainer at the top, because allowing the upper portion to lean back over the layout will cause the extended outer section to be out of vertical.  It will tend to try to return everything to vertical!  A possible alternative to a retainer at the top would be Velcro on the underside of the outer section, and and a matching piece on a "leg" below the benchwork.  There are a lot of possible solutions, and the best will depend on your chosen design, and the exact arrangement of your room. 

[Lemosteam]

IMHO, Clearances in the stops will prevent this design from allowing the track to both align and be flat across the span.

I.e. Exaggerated,  \/\

Adjuster screws could be added to prevent this however.

This is why I suggested the hinge pins be vertical originally.

[jagged ben]

I haven't been following this thread the whole way, so apologies if i missed something, but...

Why aren't we suggesting a simple liftout section supported at both ends?

A 'T-Girder' construction of sufficient strength should have no problem spanning 10ft.  (or if it does, put a hinged leg in the middle).   No hinges necessary, easy alignment.

[Cajonpassfan]

I haven't been following this thread the whole way, so apologies if i missed something, but...

Why aren't we suggesting a simple liftout section supported at both ends?

A 'T-Girder' construction of sufficient strength should have no problem spanning 10ft.  (or if it does, put a hinged leg in the middle).   No hinges necessary, easy alignment.

Yep. See my reply#25 a ways back. Didn't get much traction; not complicated enough I guess
Otto K.

[nkalanaga]

I doubt that clearances in the stops would be much of a problem.  I'm suggesting that the stops be flat bars extending 4 to 6 inches onto the adjacent part, and with no need to slide into or past each other, there's no need for clearance between the stop and the bridge.  Any sag will be far less than the bumps often found on modular layouts, and long trains go over those with no problems.  The clearances in my drawing were simply to keep the parts separate for easier viewing.

[OldEastRR]

This really IS an Engineering Report! OK, who's got the plans drawn up for the swing bridge solution? 

[nkalanaga]

If you think some of the ideas here are getting odd, how about a prototype moveable bridge?  This is the Steffenbach Bridge, on Furka Pass, Switzerland.


This picture is from Canadian Railway News, which says "Photographer and date unknown".  It shows WHY the bridge folds up.  This is a spring view.

[nkalanaga]

After looking at the Steffenbach bridge a while longer, it might work for a bifold model bridge.  Instead of alignment bars to keep the center hinge horizontal, put a hinged leg under the fixed span, with a "leg rest" on the layout leg.  When the bridge is raised, the leg will fold back against the underside of the fixed span, and the outer span will fold against that.  You might need spacers between the center hinge and the two spans, to provide space for the leg when it's open, but the leg will guarantee the fixed span is horizontal when closed.  Since the outer end of the fixed span would now be supported, the outer span will be solidly supported at both ends, and there should be no sagging or other alignment problems.  Making sure the leg goes onto the rest, while the outer span ends up on the far abutment, will take both hands, making closing the bridge a little more complicated, but that might be worth the simpler track alignment.  Eliminating the alignment bars would also allow a few extra inches for the length.

Basically, you'd be building the right side of the diagram, except that the far right span would hinge up, instead of sliding back.

If you're handier than I am at designing and building machinery, it would probably be possible to design a leg with a sliding lower end, allowing it to remain attached to the layout leg even when open.  I won't even try to figure that one out...