# Removable bridge



## norgale (Apr 4, 2011)

I am sick and tired of having to duck under my two bridges so I looked on YT for some info on removable bridges. Found one that is just what I want but the guy doesn't explain what he did to make it work, the photography isn't very good so you can't really see how the bridge works and looking over the comments on the video he doesn't seem answer any questions.
So I'd like to bring this project to this forum and see what we can come up with for a removable bridge design. Here is the video to give you an idea of what I'd like to make.
http://youtu.be/AvAurH09hGg

The two push button switches under the bridge obviously turn the power off for about two feet on either side of the bridge so the trains can't run off the edge when the bridge is out. However how does the power get the bridge rails when he reinstalls the bridge? Also how are the two push buttons wired? Pete


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## Davidfd85 (Jul 4, 2011)

Pete have you thought about a drop down instead of a lift out?






I can tell you how to build it and wire it with a safety too. 

David


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## norgale (Apr 4, 2011)

Looks interesting David. Show me more. Pete


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## DonR (Oct 18, 2012)

Pete

I don't know how the bridge in your post is wired but it would
be very simple to use a small metal contact point for
each rail on the bottom of the bridge.
A matching set of contact points are on one bridge
support and are powered by your
track buss. Thus when your bridge is in place the
connection to the rails is made by the contact points.

You could use small bits of brass or copper to which the
wires are soldered for the contactors.

You could use the same type of contact points to cut
power to the tracks either side of the bridge also if
you didn't want to buy microswitches.

Don


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## gunrunnerjohn (Nov 10, 2010)

Much easier to use a microswitch and/or relay and just wire around the bridge. For our modular layout, we have a 4 foot section with a lift bridge. When you raise the bridge, it powers down the two adjacent sections and the bridge to avoid accidents. I used a microswitch and a couple of relays to control the two tracks across the bridge.


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## tjcruiser (Jan 10, 2010)

Pete,

Whether drop-in or pivot-down, I would suggest incorporating some tapered keyways at the ends to ensure track-to-track alignment. I think you'll find that a tapered keyway will "seat itself" with a lot tighter / repeatible tolerance than those brass latches.

Cheers,

TJ


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## gunrunnerjohn (Nov 10, 2010)

Our lift bridge has 1/2" steel pins that drop into mating sockets on the base, when the bridge is down, the tracks match perfectly.  I wired a micro-switch and relays to kill the power to the bridge and the adjacent modules when the bridge is up. We're going to add some flashing LED's in the side of the bridge, just haven't gotten it done yet. 

We're over at the TCA convention this week in Cherry Hill, I'll be running tomorrow and Saturday.

The lift bridge is at the close end. This is only about 1/3 of our modules, as we didn't have nearly the space to put the whole show on. We have a 28 foot passenger station, a number of other four foot modules, and a 20 foot six track yard that goes down the middle when we have the full configuration.

We welcome all visitors.


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## norgale (Apr 4, 2011)

Some great ideas here.The drop down is good but my bridges are high,at least one of them is and would stick out too much when down. The layout is in a shed where I have to move things in and out sometimes so a lift out would be safest. The bridges can be laid up on the adjacent tracks without damaging anything. The pin idea sounds good as there should be a way to align the bridge without going to a lot of trouble. A key way of some sort would work too as per TJ. I'd have to take a closer look to see what would be best. I like the idea of warning lights at the bridge too. The more lights the better. 
John any chance you could get a picture of how your micro switches are mounted and wired? That might help a lot. I'm not even sure what a micro switch looks like. I don't recall having ever dealt with one. Pete


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## Biggie (May 14, 2014)

Off topic but really worth commenting: Great layout gunrunnerjohn ! :thumbsup: I checked your links (http://www.npog.org/) but did not found any updated gallery of this layout. Is there a thread on this forum, thank you ?

@norgale: wishing you to find the best possible solution for your removable bridge  I also like the idea of warning lights included - better be safe than sorry that is for sure.


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## norgale (Apr 4, 2011)

Davidfd85 said:


> Pete have you thought about a drop down instead of a lift out?
> 
> 
> 
> ...


You did a nice job on that David. One of my bridges sticks up about 6 inches so in the down position it would be in the way of walking through. I think I need to go with the totally removable bridge and there are two of them side by side. Pete


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## gunrunnerjohn (Nov 10, 2010)

Here's a couple of shots of the bridge open and closed. This is hot off the press, this is at the TCA Convention today.


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## norgale (Apr 4, 2011)

WOW! So your right there. How about a shot of the hinge side from the track?


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## gunrunnerjohn (Nov 10, 2010)

I'll be running there tomorrow, if I think of it, I can take some shots. Of course, when we get back, we'll still have the bridge...  The hinge is just a couple of large hinges and we have the bridge mounted on 1/2" Lucite. With the Lucite and the bridge base, it's very rigid, and that has never been an issue.


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## norgale (Apr 4, 2011)

Those two shots are great John as is the layout. When the bridge raises up, the tracks,which are level and snug so the trains can run over the joint safely,must rise up a tad to over ride the adjacent tracks or the hing will bind the tracks against each other. Wondering how that is avoided. Both my bridges are at an angle to the layout table so that further complicates things. Anyway I getting more of my junk out of the shed so the room to work is expanding some. I should be able to figure this out with some pics from you and the rest of the guys. Just went out to the shed and turned on the AC and it made all kinds of" thunking" noises. Must be a rat or a snake stuck in there somewhere so no train work tonight. Pete
Turns out a tendril from a plant grew up into the back of the AC and got tangled in the fan. All ok now.


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## Davidfd85 (Jul 4, 2011)

Hey Pete, Sorry it took a bit to post these, been working on some weathering a few cars.

Here is the construction pictures of my drop down bridge. The deck is 3/4" plywood wide enough for two tracks and a roadway.

Measured and cut the length and cut off the short end at a slight angle.
 



Then mounted the short side with angle brackets.




Made a frame of 2X2's and attached the hinges 



Clamped in place and mounted hinges.



I got 2 flat bar door slide locks from home depot. Mounded and adjusted them making sure everything was level.



When I put down the roadbed and track I just cut the angle to match and checked for level and no hanging when the bride is dropped.


For the wiring I don't have any pictures of that but what I did is use just simple flat pieces of metal for contacts. Hot wires run to the dropping end of the bridge attaching to just screws under the table end. Then the hot wires run to a block like this one.

From the block I wired to the track on the bridge, to the far side for a safety zone about 12 inches back. Then back to the drop end and a second set of contacts to feed the safety zone on that end.

I have had no derailments at the bridge to date. I have had the contacts loose touch but a quick simple touch of bending them up slightly for better contact on the screws and done. The safety zone works very good. I have run my trains to it with plenty of stopping room.

Hope it helps.

David


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## norgale (Apr 4, 2011)

Good picture of the track Dave. I would assume that by angling the cut the other way the track could be raised with no problem. Why didn't I think of that? And I see what you did with the wires so that will be easy enough. Looks good. Thanks very much for posting the pictures. Helps a lot. Pete


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## Big Ed (Jun 16, 2009)

gunrunnerjohn said:


> Here's a couple of shots of the bridge open and closed. This is hot off the press, this is at the TCA Convention today.


Nice bridge John, it almost looks like another line can be added.


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## gunrunnerjohn (Nov 10, 2010)

I kinda' wish we had gone with three mainlines on the modules, but it's a bit late to change.


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## The New Guy (Mar 11, 2012)

norgale said:


> ...When the bridge raises up, the tracks,which are level and snug so the trains can run over the joint safely,must rise up a tad to over ride the adjacent tracks or the hing will bind the tracks against each other. Wondering how that is avoided...


Not to speak for John, but it's all in the offset - notice the tracks leading to the bridge extend beyond the pivot.


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## norgale (Apr 4, 2011)

Ooohhhh yyyaaaaaa! I didn't see that before. Ok that makes sense. Thanks for pointing that out. pete


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