In practical terms, what is the turning radius of a Shay locomotive hauling lumber with short old time cars? What would be the bare minimum and what would be the optimal minimum?
Depends on how the model is built, probably something less than 12" if the trucks swivel enough. It will likely be able to go around a tighter radius alone than it can with cars attached - coupler swing starts to come into play, even if the loco wheels can swivel enoug to stay on the track, the coupler may push so far to the outside that it knocks off any cars coupled on.
Like I did for testing my curves, your best bet would be to pin down a couple of pieces of track as a temporary test before making anything permanent. If I hadn’t tested the curve spacing beforehand, I would have ben hosed now.
–Randy
Might help if you specified if you are inquiring about a protoype Shay, or a model one, and in which scale. Also which model - HO has the Bachmann and Roundhouse models. On30 and G have Bachmann models. There are of course many high priced brass models in many scales.
Bob Boudreau
The new N Scale Atlas shay will go around 9.75 rad curves with no problem…don’t know about other scales…
Sorry, I don’t have a model in mind. I was thinking in terms of an HO layout. I was sure I put that in there, but I see I didn’t.
HO Shay models many times have a different turning radius from one side to the other. When making a turn to the right, the universal joints close up and can bind. Turning to the left, you can have the shafts slip out of the universal joint - I have seen this happen!
I suspect a small 2 truck Shay can get down to 12" radius, but coupled with 36’ cars, I would not want to run much under 15" radius.
Jim Bernier
SpaceMouse: There are two-truck and three-truck Shays–three-truck Shays would have a wider turning radius. There are also other geared locomotives (Climaxes and Heislers) that were used for logging–on the Northcoast one found a lot of Heislers. Rivarossi makes a gorgeous Heisler but it isn’t cheap.
Ideally such a locomotive should be able to handle a 12" curve with no problem, even with 36’-40’ cars.
This is more of an overhang issue. Some of the guys on the Bachmann site got their Bachmann shays to navigate a 12" radius curve. The cars depend on what you are modeling. A lot of the guys modeling logging use disconnects as those offered by Kadee. A disconnect was a truck with a log bunk. They were used in tandem and were connected either by the load or by a bar called a rooster. There are pictures with a load being over 120’ long and the belly dragging on ties, rail what have you. These originated in the link and pin days and were carried over to the knuckle coupler days and some of the early couplers had provision to connect a link and pin car to a knuckler car. They were finally outlawed as they required a company of brake men with hickeys ( a bar to provide leverage on the brake wheels) to set and release the brakes. Laws promoting safety wanted a braking system that could be controlled from the cab. The disconnects gave way to skeleton cars with air brakes because of this.
The grade of the radius makes alot of difference in what the Shay will handle. Mine(On30) handle 15" radius on the flat with no problems no matter the number of cars. On a grade is a whole different matter. I have a 18" radius curve on a 6.5% grade that derails the front truck with more than 5 cars. I have 2 of the Shays and both do it in the same place. Have changed the track and didn’t help any. If I MU both locos, they will pull 15 cars through the same curve with no problem.
So, be sure and build a test track to try it out if you are going to have grade on a curve.