Turntable differences - Re: Model - turntable

Hi,

I offer this as a point of interest.

This photos show the three types of turntables that I have built models of. Althought the "M" frame is not really a gallows turntable, it is wood.

The "H" frame (middle) turntable is the original Mil-Scale kit from about 1970. For modelers, I found a stain Mom had used on some furniture and pre-stained the wood. No weathering or paint.

According to the Mil-Scale instructions this was based on "H" frame gallows turntables used in upper Michigan. It is a 65' (9" in HO) model.

Notice the differences between the Mil-Scale design and the D&RG Monarch photo. There is a second timber on the main support timbers for part of its length. The H frame is different and the horizantal members are tension rods made of iron or steel. The main timbers (ties) between the tower and the spider are heavier than other ties.

The kit I produced had the extra Member that the D&RG had. By omitting it, the table takes a slightly ddifferent look.

I took plans from somewhere (I no longer can find the reference) for the "A" frame tower that had two separate members on top of the tower. I used the same deck as the "H" frame kit.

Notice the differences between the model "A" frame and the photo from the Nevada State Railroad Museum. Different bracing, guy wires and the single top member.

Many know of the steel turntable bridge on the Georgetown Loop. Notice that the M frame would not work as a bridge. The top horizantal member is a tension only member and would collapse when loaded beyond the failure point of the main stringers of the deck. This could be made to work in one of two ways - change the upper chord to wood (for compression) or add a pier (or bent) under where the pivot point of the turntable had been.

Food for thought.

Doug vV