I am in the layout design phase and need to determine the minimum radius I can use for hidden track, with reliable operation of passenger equipment being the limiter.
I picked up a bunch of Branchline heavyweight kits on the cheap which remain unbuilt. They have become a bit of thorn in the layout design department, as I can’t find any consensus on what kind of minimum radius they require. Branchline doesn’t say. A couple of retailers say 22 inches, while postings on various forums run from 30 to 36 inches. That’s quite a discrepancy.
For the space I have available, 22" is no sweat, 30" is doable, but 36" is really pushing it.
Is there anyone with some of these cars that can say what the minimum radius for reliable operation really is? For this hidden track purpose, please consider reliable operations as consistently staying on the track whether pulled or pushed. I don’t care about appearance or the ability to couple on curves.
Depends on whether or not you put the steam lines on. I have several of these kits and there are a few things that Branchline has done to allow for smaller radius curves. IIRC, 36"r is needed if you want the steam lines and diaphrams on. Removing the steam lines, diaphrams, and notching the frame will get you the 22"r. I believe you could get away with only removing the steamlines and notching the frame a little with a 28-30"r with no issues.
I’ve built a couple of the Branchline Heavyweights, and managed to get them to work very well on a 22" radius. Here’s a picture showing what I did for each truck:
The arrows point to places I had to file or trim. The circle shows where some details were left off for coupler clearance. Branchline suggests leaving a part off the trucks for clearance, but I decided to put that on and instead file the frame so the truck would be stronger. The brake lines can be left on as long as they’re trimmed. I also clipped a little bit off of the coupler box centering springs so the box itself could swing a bit more. As you can see, I also added a couple thin washers between the trucks and frame, because the car was sitting just a little bit low.
As long as it’s on the track, I never even see all the modifications. The cars work great, and it was completely worth it to build them.
Yeah, what he said!! I just looked at the instruction sheet and the biggest thing it calls out is leaving the coupler yoke off for anything under a 28"r.
I’m with Darth on these things, they are nice to build. I like putting these together more than the $6 P2K stock cars I got at the LHS.
I picked up a couple of pre assembled 12-1s on the cheap, and out of the box they wouldn’t take a 32" curve. I loosened the truck screws and they ran without issue.
I am currently operating an interim (pending moving) layout using Kato Unitrack. My curves range from 28" to 22" radius. I have a large fleet of Walthers heavyweight cars, and recently assembled a test train with a P2K E7, and 3 paired window coaches - out of the box. The train was very derailment prone on #6 crossovers and on the curves. I removed the trucks, squared them, lubricated the “journals” with LaBelle #102 oil, and re-assembled the cars. The train now takes even the 22" radius loop without problem, with stock couplers and diaphragms. These cars are recommended for 24" radius curves as a minimum. if you are careful assembling the Branchline cars, they should be able to take a 22" curve no problem as long as you do not create any binding. Of course, there will be extreme overhang, but if you can build a layout with 28" or 30" curves you will be ok.
What anyone else says about a question like this is only theory to you because their experience in on their layout with their equipment. Experiment yourself, that will give you the answer for your layout and your equipment.
