Duck-unders and Lift-outs

We have a lift up bridge for our club layout. No door hinges, but no super precision machined surfaces, either. The track on it is ballasted but it otherwise makes no attempt to look like a full scene - the hinges for one stick up above the track level. It carries two mains plus a yard lead. Like any of our other sections, it usually lives in the transport trailer, not insualted or climate controlled. It’s been around at least 10 years now, back and forth to many many shows, and we have NEVER had an issue with it.

You can;t build sloppy, but neither do you need super precision surfaces. Unlike a home layout, since this is modular, the lift bridge piece includes the threshold, so bridge up, it’s sort of a U, brodge closed, it’s a flattened O. The track across it is perfectly straight - that makes it easy to keep good enough alignment. Down, the free end rests on a shelf, with a spring laoded latch underneath to hold it down.

–Randy

Do you have any pics of this? Pretty heavy duty! I like the idea of a motorized lift - makes sense on a club sized layout. But guessing it could look ridiculous in a ranch house basement…?..

I have, both, a swing-up and a drop-down section. The drop-down was designed that way because the overhead room was limited. They were both wired directly to the movable sections, then the approaches were fed from them. So, in order to move the sections, power is cut to the approaches via connectors, thus preventing drops into the Concrete Chasm.

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The tabs extending from the drop-down section are attached to the underside of the section, then clamped in place. I drill a 1/4" hole through the drop-down section and the stationary section. I sand a taper on the ends of 2 1" long dowels, then glue them into the stationary section.

While the sections are still securely clamped, I attach a slide bolt assembly that will hold the drop-down in place.

The picture below shows the diagonal cut in the rails. This allows the drop-down section to be raised smoothly. The drop-down section is secured in place, the track is laid and ballasted bridging the gap, then the gap is cut.

Henry,

Yes, the hinges are on top of the benchwork. One of the two traveling club layouts I have seen even had the hinges raised on a block of 2x4. As mentioned, the hinges on one are disguised by the burlap, grass mat or whatever you choose. Your scenery is used to conceal the hinges. If you didn’t use it often, you could even have the hinges hidden by a removeable building.

Since I plan to have scenery on the moveable portion, I prefer to have it out of harms way.

Have fun,

Richard

Hi. I used small blocks to elevate the hinges. I second the suggestion to add a switch to shut the power off (see 2nd picture below - it’s the dark button embedded in the wood support). I have more than once tried to move a loco while the bridge was up… Simon.

Simon

Nothing is foolproof, but you can make an attempt. How far back do you cut the gaps to isolate a sectionw hen the bridge is up/down/out? Maximum train length? What about that day you run an extra long train to impress some visitors. Bridge is out, but you are backing slowly towards it. How many cars get shoved off the edge before the loco crosses the gaps and gets to the dead section?

–Randy

Has anyone tried to build the lift and pivot gate ( May 2014 MRR pg 58) …considering it for my layout… have an issue with overhead clearance and thought this might work as opposed to a straight lift up gate…

Don’t really like either one. No mater how you make the hinged end and the fixed end you will have movement and alignment problems.Even if you could attach the pivot end and the fixed end on a steel post mounted in concrete , you still need to be able to hold the movable section to a fixed length. Wood grows and shrinks over time , and the pivot (hinge) will wear over time and need to be adjusted. I think to some point it can be made to work but will require upkeep. I would use one rather than have a duck under-has we age, the DU gets to be a PITA! Or at least a pain in the back.

In my case, the power shuts off for the entire layout.

Has anyone tried the liftout bridge designed by Lance Mindheim, see: https://lancemindheim.com/about-us/removable-bridge/

Randy,

The question of how far should the shutdown track extend has changed with the advent of “keep alives”. For small layouts, I think snjroy has the right idea, shut the whole layout off. However, for large layouts great care needs to be taken, as with the keep alive a loco can cover a lot of distance before it comes to a hault. Since I frequently see 100 car trains running on modular club layouts with multiple tracks, at train shows. I would think the wiring would be a nightmare to do. Not sure just how one would do it, but I think some sort of block to come up and block the track, firm enough to hold the approaching train.

Sounds like a new project for some of our mechanical engineers.

Anybody got any ideas?

Goos luck,

Richard

As for the electrical interlocking of the lift out, for me it is simple. As a DC operator, the entire block on either side is dead if the section is out. Those blocks are longer than any normally operated train. So it would be hard to even back a train off the edge…

Sheldon

A fold-up will automatically block one side of the gap, and I suppose it wouldn’t be too hard to have some sort of block, perhaps not automatic, for the other side as well.

How many of your engines have keep-alive circuits? And are these big engines that handle large trains? Personally, I wouldn’t bother with a keep-alive on anything bigger than a tank engine or a trolley.

But you’re right. Keep-alives add another complication to a dead track to protect a sometimes-gap.

I have a simple rule with keep alives - I don’t use them. No need to. I’ve never had any issues with locos stalling , even at speed step 1 over turnouts or anywhere else.

Since I use Loksound for all my sound decoders, if I DO need a keep alive, it will be the 3 wire type. Why? Because the 3 wire type can be programmed to provide keep alive for a set amount of time instead of “as long as the capacitor has charge in it”/ I have one loco with a keep alive, it came that way from the factory. I can pick it up and it runs across my desk and almost goes off the edge - I pick it up and place it back on the desk and it will run off the edge a second time if I don;t catch it. That’s ridiculous. You would NEVER EVER need keep alive for that much time. The idea is to get across a short dead section, or an unpowered frog - a second or two is MORE than enough time.

The only other option is, instead of having the bridge being up cutting power, instead it cuts in a circuit that generates a DCC broadcast stop command - that way even a loco with a keep alive will get a stop signal, not loss of power, so it will stop. Momentum might still defeat you, if turned up. Plus this needs to be truly isolated - double gaps are not enough, as metal wheels or an all wheel pickup loco would bridge the gaps and link the main DCC system to the stop generator - perhaps frying something.

–Randy

The more I have thought about it I’m going to make some adjustments to build a lift-out so I can run continuous as I’d originally planned with a duck under. I’m going to narrow the benchwork to accomodate a lift out section. I can see hating a duck under in short order, and with a layout height of barely 40" I would have to slide under with a car mechanic or furniture dolly. No fun.

On my layout, also DC, it’s equally simple to add a safety zone when the liftout is not in place.
I first gap one rail of the approach tracks on either side of the liftout, then run wire from the still-live rails beyond the gaps to a four-pronged female receptacle on the layout’s fascia, near the liftout. When the male plug is inserted, it not only activates the rails on the liftout, but also feeds power from those now-live liftout rails to the other two prongs, which in-turn, power the approach rails on either side of the lift-out.

When the liftout is unplugged and removed, the approach tracks revert to non-powered ones.

I’d guess that something similar could be done in DCC, too.

Wayne

On the layout I’m presently building, I have a swing gate, that swings in towards the center of the layout. It has a 24" “door” opening. I haven’t figured out quite how to rig it electrically yet (I’m DC). That project is a ways down the road, as I have just gotten the plywood sub roadbed and the backdrop installed. After touching up the backdrop and painting clouds and a horizon, I will be ready to lay track. I chose to use a swing gate, rather than a liftout because I have limited space and where to put the section when not installed is a problem. And, I don’t particularly like duckunders, no matter how high the benchwork is.

That’s the key point. On a former layout I had a duckunder, but the layout height was 58 inches and the height underneath the duckunder was 56.5 inches. It was really easy to duck under even while carrying things.

I’ve tried lower heights but find them unsatisfactory, my current layout is 50" and fortunately I have the space to avoid duckunders (or liftouts).

Paul

Having built a double deck layout with upper deck benchwork in that 58" range, I agree that makes for an easy duck under.

I also learned that I would never want benchwork that high again, so a good lift out is necessary.

Sheldon