The term "pivot table" is something I came up with for lack of a better description. The original design for my N-scale "P & C RR #3" layout's Altoona Yard (the storage yard under the layout) called for more than a dozen turnouts. Considering, on average, scratch-building one turnout takes me about a week (building track, gluing ties, installing the turnout, installing the Tortoise, and hooking it up and debugging it), I was looking at several months of work. Never mind the tremendous amount of space they would require.
The idea of a pivot table came after evaluating turntables and transfer tables. Neither really fit the area. When I was browsing through the 1995 Model Railroad Planning issue I stumbled across "Keeping Appointments with Convoys" by Doug Gurin. In his layout's design he shows a "pivoting sector plate" at the end of a lower-level yard. I liked the idea and took it a step further. Instead of being able to move just one locomotive at a time, I made mine 15 inches (200 scale feet) long so that it could hold a switching engine and several freight or passenger cars. Is there an example of something like this in the real world? Probably not, but this part of the layout had to be more functional than prototypical. As you can see in the diagram below, the concept is rather simple. A single piece of 15-inch long flextrack pivots at one end, while the other end travels over some range. My implementation is one where there will be no electro-mechanical means of moving the "bridge". I will simply move it by hand.
I wanted to do as little damage as possible to the plywood base for the Altoona Yard, so I decided to use a piece of Masonite hardboard for the base of the movable bridge of the pivot table. All I had to do was clear the cork sub-roadbed in some area. This photo shows the flextrack being glued to the piece of Masonite board. The board is 5/8" wide to match the width of the ties. In retrospect, I would recommend making this wider because it is too easy to grab the locomotive rather than the pivot table. The two parts are being glued together using Liquid Nails for Foamboard. Before gluing the track to the board, I rounded the short edge near the pivot point so that it is easier to turn.
Once the glue was dry (about three hours later), I drilled a 3/16" hole in the Masonite board and the plywood base. This hole matched the piece of metal tubing I am using for the pivot point. I chose a hollow tube so that I can guide track feeder wires through it. The metal tube was glued in place using superglue.
In the next photo you can see the final preparations to the bridge. I cut the rails to length and I removed the plastic ties that may interfere with the free movement of the bridge. I also filed down the end of the rails to hopefully cut down on derailments. Finally, I routed and soldered the wires through the tube and under the ties. This was not easy. It doesn't look pretty, but with a bit of paint it will be hidden. The pivot table isn't necessarily that easy to see under the layout anyway.
I removed a section of the 1/8" thick cork that serves as the common sub-roadbed for the entire yard. Since the pivot table bridge was made out of 1/8" Masonite board, the tracks will all line up nicely. After the cork was removed, I sanded down the area.
Here is a shot of the pivot table bridge in place just to test fit it.
I have wired all the tracks and the pivot table bridge up to the 14-gauge track feeder bus I ran under the table. The back storage track has been installed. I have been able to successfully run a train down the helix, over the pivot bridge, and onto the storage yard. This is very exciting!
The track has been installed. There is a total of 71 feet of flextrack from the front to the pivot table in the back.
Here is an updated photo of the pivot table in action. After spending a little time doing some switching work using the pivot table, all seemed to go well. I wouldn't recommend this solution for a busy switch yard, but for this layout it is just perfect. It was cheap, quick, and it is effective.
Here's a picture of the yard serviced by the pivot table. The exciting part about this yard was that I was able to put out all of my rolling stock in one area. The first time I had been able to do that. About three weeks after this photo was taken, I tore down this layout to start work on "P & C # 4". Oh well. Hey, at least I have photos to remember this by!