Thursday, June 10, 2010

A Cure for the Aching Back

Since the train show in St. Cloud earlier this spring, my interest in modeling has been rekindled. What had been the beginnings of a small HO switching layout in my basement has seen significant expansion, to the point that I now have a continuous mainline run of about 120'. I enjoy this, since when I am down in the basement working on models, I now can have a train running continuously, and it passes above my workbench every three minutes or so. However, in order to have this continuous run, the tracks have to cross the doorway entering the room. I contemplated whether I should build a duckunder, some type of swinging gate, or a bridge to cross the doorway. A temporary duckunder convinced me that whatever solution was selected would have to allow me to enter the room in an upright position. Here's the doorway that needed crossing:

One of my personality traits is that I enjoy solving problems like this in the most economical way possible. In other words, I'm pretty cheap. I didn't want to have to buy a bunch of fancy hardware. However, at the same time, my cheapness convinced me that whatever method I used had better not let an expensive Genesis locomotive go crashing to the cement floor. With these thoughts in mind, I sat down and began pondering. The first thought was a lift up bridge. However, I kept seeing it come crashing down on my head in my mind. So how about a lift out section? That seemed simpler, but probably not practical for someone who can set down a camera and 30 seconds later swear that some basement troll must have grabbed it and taken the camera back to its lair. I needed something that I couldn't lose. The drop leaf style bridge came to mind. And so the basic design was chosen. I figured, in order to have a reliable bridge, I needed something substantial to fasten it to. An armload of 2x4's and some drywall screws provided a foundation on one end. The existing benchwork on the other side of the bridge was surprisingly stable. The hinged end would be on the side with the 2x4 framework, as shown here:

So far, things were going pretty well. But now came one of the harder parts of the design-how can I make sure that the tracks on the bridge line up perfectly with the tracks on the benchwork, every time? I had to stop and play with trains for a while to let that question turn over in my mind. Eventually, I came up with the idea of some type of wedge arrangement, where alignment in both the horizontal and vertical planes should be repeatable. I could try and describe how I did this, or I could just show you this picture:

The cam is removable, so you take it out, raise the bridge, then plug the dowel into a hole and twist the cam to lock the bridge in place. Reverse the procedure to lower the bridge. Store the cam in place, and you might not lose it. I haven't yet. I built the entire thing before installing the track, then with the bridge locked in position by the cam, installed the track. Then I used a cutoff wheel in a rotary tool to cut the track. Here are the joints on either end of the track:

I powered the tracks by soldering feeders to each rail and leaving enough slack so the wire flexes as the bridge is raised and lowered. Here is how the bridge looks when it's in the operating position:

The bridge "plank" is a piece of birch that is about an inch thick. It's very stable and so far I have seen no problems with alignment. It's on of the rare projects that worked out pretty well the first try. It is a little rough looking, and I still will add some type of electrical interconnection to prevent running a train into the canyon if the bridge is open, but I haven't found just the switch I want to use for that yet. Remembe, I'm cheap and want to get the feeling of getting a good deal on that switch.

Here's a short video of how it actually works.

Hope you enjoyed this little story!



Bil said...

Quite inventive!

BB-Idaho said...

Did I count 27 coal cars crossing the bridge? I model n scale with 200 ft
double track main..and have only 25 per unit coal train. You gave me a good excuse to get a bunch more..

dorcheat said...


I sincerely hope you and your wife were not hurt in the tornado outbreak during June 17 in Wadena.

As an atmospheric scientist and of course, a railfan, from DL, these type of tornadoes are very rare in northern Minnesota and more common in Kansas and Oklahoma.

I hope your home avoided damage as well.

Take care!

Jim said...

My wife and I are fine, and our house came through the storm with no damage. The tornado passed 2-3 blocks west of us. I am shocked at the amount of damage and the distance the tornado stayed on the ground. A number of our friends and fellow church members were not as fortunate and suffered heavy damage to their homes.