More on link and pin couplers

The discussion on link and pin couplers reminded me of Harold Minkwitz's solution to L&P couplers in On30 scale. He documented it on his web page at Pacific Coast Airliner. He had 18 inch radius curves on his layout and the coupler swing on the tight curves caused L&Ps to derail the cars. So he devised a modified 3/16th inch staple as a "U" shaped hook to connect the cars. These allow for swing and provided near slack free operation. The coupler drawbars on the cars are basically modeled to scale. So in photos the cars look prototypical. I think this is very clever. I may try this idea if the link and pins prove too troublesome.

Harold's site had lots of neat and useful information. He has since taken it down.

Spline Roadbed

We have started extending the railroad mainline from Falmouth to Stoneman's Station. I decided to try using spline roadbed for this part of the line in an attempt to save materials by avoiding cookie-cutting large sections of plywood. Here my brother is installing the first piece of pine spline roadbed.

We are using a combination of pine lath and composite wood. The pine lath is 1/4 inch thick and is not flexible enough to bend to a 30 inch radius without pre-soaking (actually I now learned that this is not true. It can curve that tightly without soaking). For the tightly curved parts we are using a composite wood material available at DIY stores. The material is a combination of wood and plastic with a fair amount of entrained air that makes it light. I don't know exactly what the plastic is, but it is something like expanded foam. In any case it behaves a lot like a flexible piece of wood. There doesn't appear to be grain, but it can split if you don't drill pilot holes for screws. Since it is pre-painted with a gloss paint, carpenters glue doesn't hold it as well as raw wood.


I decided to add a small trestle across a creek to the scene between Stoneman's and Falmouth, inspired by the scene at the left, actually on the USMRR City Point line. Note the rough construction of the bridge and the lack of fixed abutments. Since the Aquia line existed before the war, it is possible that stone abutments may have been used, as at Potomac Run. So I may use them instead. I'll make that decision later. This is not the big trestle over Potomac Creek that is coming later. Note the use of sills on the bottoms of the trestles instead of pilings driven into the ground. They also do not seem to use closely spaced bridge ties used in later bridge construction. Ties appear to be thin, certainly not the regular thickness normally used elsewhere on the railroad.



To drop the terrain, we cut away the main beams along the length of the bench work and added splice plates below. This creates about 5 inches of vertical distance from the rail top to the creek bed, enough to house a small trestle. The pink area just in front of Mark's arm will be the location of the trestle.










The advantage of splines is that they tend to assume natural easements as you install them. The trick is to ensure that you don't inadvertently create kinks or sections with too tight a radius. I made some 30 inch radius templates using 3/4 inch pink Styrofoam. These were easy to cut with a Stanely utility knife. When clamped to the white lath pieces they are doing a good job of holding the radius while we adjust the roadbed to the desired alignment.
Initially I thought a 36 inch radius would work here, but alas, that was going to cause the track to swing too wide into the aisle. So I am using 30 inch radius.


The photo shows some freight cars on the track to see how they will look. There will be an 1/8th inch thick Aspen Plywood section of roadbed on top of the splines and the ties will be glued to that. I am laser cutting the Aspen plywood to make bendable kerfed-roadbed pieces, but I'll discuss those in a future post as we install them.

I am worried about running passenger cars on these tight curves. I'll have to build some passenger cars so we can test it out. Although things look good on paper, when it actually comes time to build, the big radii that O scale requires is a real challenge in my tight space.

The dilema of links and pins

I am beginning to have second thoughts about using links and pins on my railroad. Although the prototype railroad used links and pins, they are tricky to use in model railroads. I haven't really given them a college try yet, as I only have 5 freight cars built and only three have couplers. But..... what little I have done has been problematic. They are very tricky to get coupled up and frequently the car you are coupling is derailed in the man-handling process!

There is a design implication of using links and pins too. The harbor end of the layout would benefit from a pier along the back wall. It is difficult to reach portions of that area. It would be impossible to couple a link and pin in that area. So if I stay with link and pins, then I'll have to omit that track.

But knuckle couplers aren't a perfect solution either, as there is no easy way to install a knuckle coupler to the front of an ACW locomotive without messing around with the cow catcher. The locos currently have an extended link like the prototype. Dave at SMR Trains says that this link wasn't designed to be used, it's mostly for show. However, I have tested it and it does work albeit with a lot of finicky fitting. I may have to make some links with slightly larger holes to allow easier insertion of the pin.

Another solution I am considering is to leave the extended link on the pilot and put a rule in the timetable forbidding the use of the link by road engines except in emergency circumstances. This means that road engines could only switch using the coupler on the tender. That will make things tricky operationally. I intend to build one engine that will be designated as the yard switcher. It will have the cow catcher removed and a conventional coupler installed on the pilot (either link and pin or knuckle). I also plan to have either a turntable or wye at both ends of the RR to facilitate turning the locos.

N Scale Supply Depot

About 13 or 14 years ago, John Hill built a union army supply depot diorama in N scale. I contributed many of the figures, the sailboat and the trains for the diorama. Here are some pictures of the project.

While it was a fun diorama to look at due to the intense busy scene, many of the structures and models were built using war game parts, which are designed for robustness and not fine scale. Thus the models do look a bit clunky. This combined with the poor running quality of N scale 4-4-0 locomotives convinced me that modeling a ACW railroad in N scale wouldn't meet my objectives. Thus began my search for a better approach that ended up with the current O Scale project documented on this blog.

Working Brakes

In developing this large scale layout I wondered if I could develop a method of adding working handbrakes to the freight cars. Even though my trains will be short, roughly 8 to 12 cars, I will probably need two man crews as the link and pin couplers require the brake men to use two hands to couple. Adding working brakes would add additional work for the brakeman and would also be realistic.

Cars in this era had brakes only on one truck. Thus the linkage is pretty simple. Using some brass 1/16th inch rod and 1/32inch phosphor bronze rod I made a brake linkage based on drawings from White's book on early freight cars.

This video demonstrates the holding action and release of the brakes. Since it looks like they work, the question is, do I want to add working brakes to the whole fleet? It adds about one and half hours to the construction time.