In the steam era the engine terminals and turntables belong together.
Turntables are used to turn steam engines - steam engines have a prefered operating direction.
Turntables also are a space saving construction to line with a storage track - engines have to be parked between services.
On my "Orange Empire" I use the engine terminals as show case for my locomotives.
It is the realistic way to store a number of locomotives on one spot.
Most of us like to have a collection of locomotives - far more than needed to operate our trains!
Since I model Southern Pacific and Santa Fe I decided to realize two engine terminals - "Taylor" for SP and "Redondo" for ATSF.
Both companies operate large steam engines. To handle them I need a 120 foot turntable.
The construction of the two turntables differ from one an other. ATSF uses a thru-girder turntable while SP uses a bridge turntable.
Scratchbuilding a personal turntable has the advantage to adopt the construction to the available space.
I would like to share on this topic my experiences I collected with my adventure to build them by scratch.
I built the SP-turntable a few years ago - I have operating experiences.
And now I started to build the ATSF-turntable.
I hope you enjoy this topic!
Southern Pacific turntable of "Taylor" engine terminal.
A Cab Forward rides the table.
Santa Fe turntable of "Redondo" engine terminal.
A GP-9 takes s spin.
This turntable is still under construction.
Planing the layout of the engine terminal with the turntable
First of all you have to determine the dimension of the turntable.
Select the largest locomotive you want to handle with your new turntable.
In my case this is the ATSF 2-10-4 Texas Class 5000 - a big locomotive.
As result I need a 120 foot turntable.
Well now look for a space to place it!
I cut a piece of paper sheet with the dimension of the turntable pit - scale 120 foot.
I moved this paper-sheet to determine the optimal location.
Where do I want to place storage tracks? Where do I want to locate the access tracks, that link the turntable with the mainline?
The turntable has to be placed onto the module in a way to let sufficient material around the future pit to garantee the stability of the construction.
I plan to have two sets of ten storage tracks each, two access tracks will be forseen.
Look at the arangement you placed onto the module from different angles.
Do not hurry with this step!
Better try different versions in a dry matter before you start cutting.
When you are convinced of your layout start the next step.
The foto shows a part of my selected layout. The second set of storage tracks will be located on an additional module to be placed later.
This is the starting point of my "Redondo" engine terminal.
Juerg Luetscher - Orange Empire
Building the module with the turntable pit
Now we start to realize this project.
The module is built on a stable wood plate (I used 23mm).
A frame located close to the turntable pit adds to the stability. The module is not alowed to bent - otherwise you never will have a good rail alignement!
The foto shows the cutout of the turntable pit, half of the frame for the outer support rail is already fixed at the modul.
For the foto I placed the raw turntable-bridge into the pit - yes it matched!
The ground-plate of the turntable-pit is still missing on that foto - this has to be also a stable plate. The turntable pivot will be fixed in it.
Do not forget to check after each step the compatibility of all the elements you build - this safes time and nerves.
Later I will show the construction of the turntable-bridge.
Juerg Luetscher - Orange Empire
Buildinng the turntable-bridge (1)
The 120-foot turntable-bridge in O-Scale is a long piece!
As mentioned before when talking about the turntable module stability is the key-factor for a smooth operation of a turntable.
I decided to build my turntable bridge using standard aluminum profiles.
The elements are fixted together with small screws.
The solid profiles ensure a stable construction - no bending at all.
The foto shows the completed raw construction of the bridge.
Details for prototypical impression of the model will be added later on.
Building the turntable-bridge (2)
Would you like to see the basic aluminum-elements the bridge was built from?
I had to cut quite a number of pieces to built the bridge.
I used only standard profiles that I could buy from stock.
The large sidwalls were cut to the desired shape.
I was able to do all the cutting work by myself with my hobby tools - but I have a large handheld cutting tool.
When performing this cutting work do not forget to protect eyes and ears! Lots of shavings are flying around.
See my conclusion: As experienced model builder you can perform such work to scratchbuild a large turntable bridge.
Stability of the bridge was my first task, the dimension of the profiles reflect that. This is some compromise I did about prototypical dimensions.
I'm shure at the finished model this will not be a problem.
This foto shows the different elements to become the bridge before assembling.
Building the turntable-bridge (3)
A different view of the profils is shown in this foto
Very nice to share the construction details with us. I found the same thing when it came to scale lengths with modern day grain elevators. When you stand those elevators up and then roll your hopper cars for loading, you see a very different perspective. A big engine requires a turntable on a grand scale but parking engines around it looks great.
O-Scale is large. As modeler we have to take this into account. In smaller scales you can realize a section of a landscape in model. In O-Scale we have to go a different way. Typically a large building can define the scene we will create in model. This building then makes the character of the scene we model. This is important, the locomotives or cars then will be set into this scene. There will be a different awarenes of a vehicle. It could be a shop scene, or a yard scene, or a platform scene. The modules we build have to be limited in depth - it is the space we can use, it is the access we have to ensure. Larger buildings can be the eye-catcher as the end of a scene. When they are high they can perfectly hide a complete wall.
An O-Scale layout can be realized as a set of individual scenes - the train then moves from scene to scene. So we can get rid of the problem of having too short tracksections for a realistic landscape and travelling distance. With the dimension of such a scene you can dive into as operator. That is O-Scale - a fascinating thing!
Juerg - Orange Empire
Mating the turntabe-bridge and the turntable-pit (1)
The step I will now describe is the most demanding one of the project to scratchbuild a turntable.
Let me start with some more information of the real thing:
A real turntable rides on a heavy gear composed of a ring with a number of rolls - this is located around the pivot of the bridge.
At both ends the bridge is equiped with a pair of support rolls, riding on the outer rail.
When a locomotive moves from the track to the turntable, the bridge tilts onto the end rolls.
The engineer then centers the locomotive in the middle of the turntable - this is done when the bridge is balanced on the center gear.
Then the bridge can be turned.
For my model I used a different principle:
In order to have a stable gap between the fixed tracks and the bridge I tried to minimize the lateral movement.
I do not want to have this tilting and balancing on my model as described above.
The model turntable bridge rides on the two pairs of rolls located at each end of the table.
It is essential that all four rolls ride on the support-rail mounted at the outer side of the pit.
The whole weight of the bridge is carried by this four rolls. To keep friction as low as possible I use ball-bearings.
The center-pin of the table has the task to keep the table truely centered.
An other ball-bearing fulfills this task.
The center-axle fixed on the turntable-bridge can vertically move in the ball-bearing.
The center-axle will also be used to turn the bridge.
It sounds a bit complicated - fotos will show the essential details!
This is my recommandation befor starting work:
Do the measuring very carefully, check twice you did it well.
When everything is ready to drill the holes, make a final double-check.
The pivot of the table must be centered in the pit - otherwise the table will touch somewere the pit-wall when turning.😫
The foto below shows the center-pin with the bal-bearing.
In the background the hole in the ground-plate of the pit.
Mating the turntabe-bridge and the turntable-pit (2)
As described above my turntable-bridge rides on two pairs of rolls located at the ends of the bridge.
The foto shows the running gear.
The pair of screws will make the link to the bridge.
Mating the turntabe-bridge and the turntable-pit (3)
Now I will do the last post about the mating.
How does the turntable-bridge look like riding the support-rail located in the pit ?
How looks the rail-gap like with the turntable-bridge in place ?
With everything properly crafted it looks very smooth and easily done.
Yes it is possible to build a turntable from scratch without a professional set of tools.
A good planing-process and a stepwise working are recomanded.
In later posts I will talk about powering the turntable and detailing the whole module to look like the real thing.
The foto shows the installed bridge alined with a fixed track.
In your next article, are you talking about how to power the track? My guess is you will discuss maybe a stepper motor and controller to turn the table to align with the tracks.
I will write about electricity in the next posts.
There will be information about my first turntable I built for "Taylor". The actual turntable for "Redondo" will be equipped soon.
I can look at a number of years of successful operation with "Taylor". I can share with you.
So read the next posts soon. 😀