Liftout bridge design/article?
- Thread starter Rigby
- Start date
Two ideas. One is a classic lift-out descibed at http://www.all-model-railroading.co.uk/amr/index.htm. The other, assuming that this is really a duck under rather than a lift out, is to use a bridge that can tilted down out of the way. A simple deck girder bridge could be used with a hidden hinge behind the abutment at one end.
OK, two feet is about 300 N scale feet long. Unless you want to build a suspension bridge, there's no prototype bridge that can span that length without a center support. Since you can't make a prototypical bridge, the easiest thing to do would be use some plywood for the support and then some styrene to simulates the abutments and sides like the bridge at http://www.walthers.com/exec/productinfo/533-164000. Extend this out to the two feet you need and we'll just ignore the fact there's no center supports.
If you make the abutments thick like those in the picture, that will give you a perfect place to set the bridge in place but make it easy to lift out without wrecking the surrounding scenery.
I'll just add a cavet from my own experience. If there's any way you can avoid bridging this doorway, do so. No matter how well you build the bridge, it will get damaged over time. This doesn't count the number of times you'll open the door and crash into the bridge because you forgot it was there. If there's nothing else you can do and have to use a bridge, just be prepared for the B&B gang to have to spend a fair amount of maintenance time to keep it in good shape.
If you make the abutments thick like those in the picture, that will give you a perfect place to set the bridge in place but make it easy to lift out without wrecking the surrounding scenery.I'll just add a cavet from my own experience. If there's any way you can avoid bridging this doorway, do so. No matter how well you build the bridge, it will get damaged over time. This doesn't count the number of times you'll open the door and crash into the bridge because you forgot it was there. If there's nothing else you can do and have to use a bridge, just be prepared for the B&B gang to have to spend a fair amount of maintenance time to keep it in good shape.
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I understand the issue with the bridge, but it has to be because I want to be able to run trains into staging and there is no room for a helix to turn them under themselves and no where else to go.
My operating concept is a big island off the coast of Maine. (Birch Island - which is a real island where we have a small lot, but is much smaller than in my railroad world). The layout will share a small room with my home office. My desk will be a built in and the railroad will run alongside the desk, behind me and around the far wall.
Under the desk/working area will be staging. The desktop will lift for access to it. Tracks will run out from staging to my left while sitting at the desk and loop counter clockwise behind me. The bridge we are discussing will connect the end of the island into the side of the desk to return trains to staging. There will be a run-through track to allow continuous operation but the operation plan calls for distinct ladders in the desk to compel point-to-point operation.
So - what I really need is an article or tips on engineering the structure, hinges, track alignment, etc. If it hinged up a suspension bridge is not out of the question... (but I'd need some serious input into the build)
My operating concept is a big island off the coast of Maine. (Birch Island - which is a real island where we have a small lot, but is much smaller than in my railroad world). The layout will share a small room with my home office. My desk will be a built in and the railroad will run alongside the desk, behind me and around the far wall.
Under the desk/working area will be staging. The desktop will lift for access to it. Tracks will run out from staging to my left while sitting at the desk and loop counter clockwise behind me. The bridge we are discussing will connect the end of the island into the side of the desk to return trains to staging. There will be a run-through track to allow continuous operation but the operation plan calls for distinct ladders in the desk to compel point-to-point operation.
So - what I really need is an article or tips on engineering the structure, hinges, track alignment, etc. If it hinged up a suspension bridge is not out of the question...
(but I'd need some serious input into the build)Well, here's an idea:
Might be a little work but it looks pretty strong.
I haven't found a good plan for a duck under, probably because each is so different. I think my plywood and fake bridge suggestion would work and you could make it drop down by using a simple piano hinge at one end.
Might be a little work but it looks pretty strong.
I haven't found a good plan for a duck under, probably because each is so different. I think my plywood and fake bridge suggestion would work and you could make it drop down by using a simple piano hinge at one end.
Ok - that's pretty cool.
Yep - I like your plywood and fake bridge routine, though I would probably rig it be raised rather than dropped. What I don't know is how to make the rails meet, though as I think about it, I am starting to envision it.
Building a suspension bridge sounds pretty cool, though - next question coming in a new thread. Nuttier still...
Yep - I like your plywood and fake bridge routine, though I would probably rig it be raised rather than dropped. What I don't know is how to make the rails meet, though as I think about it, I am starting to envision it.
Building a suspension bridge sounds pretty cool, though - next question coming in a new thread. Nuttier still...
HaggisKennedy
Coal Shoveler
N-scale, 300' scale length? Don't do a bridge, do a domino. Use maybe an 8" wide piece of wood, properly braced. Then, lay track and scenick all around it.
You may want to put hydrocal/sculptamold 'hills/slopes' on each side of the ROW. Make it look like a cut in the landscape.
With an 8" wide section (or whatever), you can conceivably put in a shallow curve, or have the trackwork move diagonally. The only requirement is that it fits either end when in place. If you do the Modular way, you can reverse the section and it'll still fit.
In N-scale, you can get away with a lot with minimal width.
Kennedy
You may want to put hydrocal/sculptamold 'hills/slopes' on each side of the ROW. Make it look like a cut in the landscape.
With an 8" wide section (or whatever), you can conceivably put in a shallow curve, or have the trackwork move diagonally. The only requirement is that it fits either end when in place. If you do the Modular way, you can reverse the section and it'll still fit.
In N-scale, you can get away with a lot with minimal width.
Kennedy
Swissengineer
New Member
Kennedy,
do you have enough space for a swing door? I think its much easier for getting access to the layout.
Stefan
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do you have enough space for a swing door? I think its much easier for getting access to the layout.
Stefan
Railfan`s Homepage
My Gallery
HaggisKennedy
Coal Shoveler
Not me. Rigby is the one who was looking for ideas.
The domino also has the advantage of being 'unusual', since folks generally will try to do a bridge. N-scale, being smaller and hopefully more lightweight, should provide the opportunity to be creative. If you make the ends the same, you can flip the lift-out end to end and still have it work. Which gives you a bit of extra flexibiity. Tired of seeing one thing on one side? Flip it!
Kennedy
The domino also has the advantage of being 'unusual', since folks generally will try to do a bridge. N-scale, being smaller and hopefully more lightweight, should provide the opportunity to be creative. If you make the ends the same, you can flip the lift-out end to end and still have it work. Which gives you a bit of extra flexibiity. Tired of seeing one thing on one side? Flip it!
Kennedy
