Here are some pictures that illustrate how turntables were manually turned and locked into position.
Here is the lock. It has three metal castings , two on the turntable to hold the “key” which is a wood 4x4, and one on the lip of the pit.
Here is a detail of the casting that holds the push pole, note the large U bolts that hold the casting to the turntable.
Nice detail. I bet those U bolts were bolted through something more than the deck planking.
Mike
Several years ago, I was looking at the Southern Pacific slim-gauge turntable in Laws, California and found that it uses a simple hinged bridge plate to index the turntable. The bridge plate is just wide enough to fit between the rails. Once the turntable was close to the desired track, you would flip the bridge plate down atop one of the rails and it would drop into place between the two rails as the turntable aligned itself with the desired track.
That seems like a common sense way to do it, along with the 4x4 pictured above, which looks like it should be long enough to fit into all three brackets. The prototype 1:1 doesn’t have to worry about electrical contact.
So, what gauge are you referring to as “slim-gauge” I don’t think I’ve ever heard of that.
Mike
I have seen a similar plate used, but instead of being hinged, the operator simply slid it forward into the radius track once the table was aligned. Unfortunately I never thought to “waste” film and take a picture of one. Hindsight is 20-20…
John
John
“Slim gauge” at Laws refers to the 3 foot gauge Carson and Colorado. It’s a common synonym for narrow gauge.
I would be very willing to wager that there’s a lineup casting at every track that ends at the turntable. I also bet the original lock bar was long enough to engage both castings on the turntable - since it won’t maintain alignment against side thrust as-is.
At the Umikoji Locomotive Museum the castings on the ‘land’ side are inverted, the box casting for the ‘bolt’ is quite long and the ‘bolts’ on both ends are driven through interlocking plant-style levers and rods by an armstrong lever (think Caboose ground throw) on the end of the turntable.
Hmm. I wonder how hard it would be to make that work in 1:80 scale. Definitely positive lock…
Chuck (Modeling Central Japan in September, 1964- with one JNR standard turntable)