Modeling the Turntable Bridge

In previous posts I detailed the construction of the turntable pit and mechanism.  Now we turn to the construction of the turntable bridge, which will fit over the bridge turning plate in the center of the pit.  The bridge is assembled from laser ply sides that are laminated together to resemble the steel girders of the prototype.

The sides were laminated with contact cement, and pressed together with wooden clothespins.  The two sides are connected with cross pieces.  I used ACC to connect the two girder plates.

The cross beam assembly and deck is made of 1/8 inch laser board and rests on the tabs on the top side of the bridge cross pieces.  Here is a view from the bottom.

Here you can see how the bridge looks with the sides fully assembled.  The outside laminate for the girders is very delicate.  Be careful not to break anything, especially if you use contact cement (as I did) and have to make adjustments when putting the parts together!  Fortunately, if you happen to break something, the repairs are virtually invisible once the bridge is painted.

As I pointed out in the previous post, the turntable tracks rest on cross beams or sleepers that rest on the bridge girders.  The top of the bridge for the model has slots for the flex track to rest in.  Along with the laser ply board the kit also contained a pre-cut length of HOn3 code 70 flex track.  When I first tried to line up the flex track ties with the slots in the bridge, I couldn't understand how to fit them together.  Then I reread the instructions, which suggested cutting the tabs that join the rails on the flex track, then sliding the ties along the rails to fit in the slots.  This took some care, as the ties had a tendency to pop off the rail.  Here I am matching up the flex track to the top of the bridge.

Once I had the flex track ties where they needed to go, I put a drop of ACC on each tie where it contacted a rail, to keep the ties from moving.  Then I dropped the track in place.

I had already painted the sides of the track with Floquil rail brown.  I still had to stain the top of the bridge and the cross beams.  Here is how the unpainted bridge looked at this point.

Just for fun, I put one of my brass EBT mikado locomotives on the bridge.  If it looked this good now, just imagine how it will look when painted and assembled!

The next step was to stain the cross beams and top of the bridge.  Actually, I could have left the center of the bridge unpainted since it will be covered with plank decking, but it was easier to immerse the entire top in a bath of gray stain, then let it dry on a paper towel.  The results were pleasing to my eye

After test fitting the top to the girder assembly, I removed the cross beams and painted the girders with Floquil grimy black.  I then used rust colored weathering powders to give a rusty appearance to the girders, and fixed the entire paint job with a coat of Dullcoat.

The planking for the deck comes in three sections, one for each side and one for between the tracks.  I secured the deck with contact cement after staining it with Hunterline gray stain.  The slots in the sides of the deck are where the handrail supports will go.

The turntable revolves around a central bearing, which on the model consists of a turning plate that fits up inside the turntable bridge when the kit is fully assembled.  But the prototype also rests on wheels at each end that run on a circular track around the bottom of the pit.  The support wheel assemblies come as laser cut parts on a sheet of laser ply.

The support wheels are made from pairs of 6 mm N scale wheels joined face to face. The supports are cut from 1/32" laser ply.  Assembly is tricky as these are small parts and have to be cemented at the proper angle with ACC.  On one or two occasions they were also cemented to my fingers!  Be careful because the inside and outside wheel supports are different.  Follow the drawings in the instructions.

Here is what the bridge looks like when fully assembled.  Note that the wheel assembles actually lie on top of the bridge.  Be sure they are turned the correct way.  The top of the bridge then sits on top of the wheel assemblies and holds them in place..

Here is a close-up view of the end of the bridge with the support wheels in place.

The last structural detail to add is the air motor assembly.  On both the Durango and Rockhill (EBT) turntables there is a motor to drive the turntable powered by compressed air from the locomotive through a hose.  I have seen videos of the motor working at Durango, but to my knowledge the one at Rockhill was never used.  So you could leave it off altogther.  However, I chose to include it.  The motor, like the support wheels, is assembled from laser ply parts that include the deck.  Here is a view of the motor in place.

As you can see from the photo, I have begun to mount the handrails, which are the last step in constructing the turntable bridge.  The rails are made of steel wire (included in the kit) which is run through wooden stanchions cut from laser ply.  I painted the stanchions black, but at this point I have not painted the railings.

Following are two views of the deck with the handrails in place.  The wire is bent to follow the air motor control deck.  Simon Cox recommends gluing the end stanchions and one or two in the middle, then running the wire through while adding the additional stanchions as you go.  This is a bit tricky, since you need to line them all up together and the wooden stanchions are fragile.

On the Durango turn table the railings lean out.  On the EBT version, the railings are vertical, which is how I made them.

Here is a close-up of the handrails for the air motor platform.  Note the control handle made of a length of steel wire.

Just for fun, you can see how the finished model will look with one of the EBT mikes sitting on it.

In the next installment, I will illustrate how the completed turntable was installed on the module with the roundhouse, ready for installation on the layout.