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Disconnect Log Cars

From Professor Klyzlr.

Model disconnected log cars have been produced in many scales and gauges for years now, but I have seen nary a one in HOn2.5. Thus, when the request came from a modelling friend to see disconnect log trains running on his logging exhibition layout, the challenge was too great to resist. Prototype disconnected log cars came in many different shapes, sizes, and configurations around the world. Indeed, many of them were constructed in the woods by
backshop crews from “Hardware only” kits to their own designs and were, therefore, completely unique.

For the uninitiated, a disconnected log car is not much more than a freight truck with a coupler on each end and a supporting “bunk” for carrying logs on
top. They are coupled together in rakes when empty for the run to the woods, and run in pairs with one log, or a few logs, slung between them forming the
“body” of a bogie car when loaded.

In searching for a prototype for my disconnects I happened upon an old Kadee catalogue advertising some of their logging car kits, one of which was for a pair of HO standard gauge steel body disconnects. The following is how I built my HOn2.5 disconnects based on this design.

Small cars such as disconnects are known for bad riding characteristics, especially when running empty, and during switching. From experience I knew
that this could usually be traced to a few key factors. Weight, friction, and couplers all play a role in the ability of any car to perform flawlessly. With these criteria in mind, I started with the following bill of materials.

  • Micro Trains N scale Archbar bogies
  • Micro Trains N scale 1129/1130 Medium/Long length Talgo couplers
  • 1/8″ Brass U channel
  • 0.140″ X 0.020″ styrene strip
  • 0.188″ X 0.020″ styrene strip
  • 0.060″ X 0.010″ styrene strip
  • KATO 11-600 N scale metal wheelsets
  • Grandt Line NBW castings
  • PECO N scale trackpins
  • 0.016″ Brass wire
  • 0.020″ Brass wire
  • Assorted small brake wheels

This list will provide enough materials for a pair of disconnects. Wheelsets, couplers, and bogies are the main limiting factors. I used Cryno Acrylate
adhesive (CA) almost exclusively during the building of these cars. Wire sizes are approximate only, use what ever comes to hand around these sizes. Once you have made one or two pair of these cars to get the hang of them, it is easy to produce them in batches “production line” style.

Couplers


I equip all of my HOn2.5 stock with “knuckle” type couplers, mainly from Micro Trains. Disconnected log cars, being so small, afford little room for fully functioning draftgear boxes. I use the MT talgo couplers in the following way.

Assemble the knuckle and shank halves of the couplers with the trip pin in place with the smallest amount of CA. Once they are together, use an
electronics type soldering iron to fuse the T shank halves together, thus holding the back of the coupler halves firmly in place. A quick touch of the
soldering iron to the rear of the coupler head on both sides will keep the knuckle end together. I used an old 40W iron I had on hand.

You should be left with an assembled knuckle coupler and a straight shank extending back from the head. Using a small file and/or X-acto knife, trim any
excess molten plastic away from the shank. With a #75 drill bit, drill vertically through the shank about half way back, and set aside.

Trucks


The main rolling body of these disconnects is essentially a Micro Trains bogie with a basic centre sill holding the couplers and bunk on. First thing’s
first. Take one Micro Trains archbar bogie and remove the plastic wheelsets.
In this application, deep flanges are an advantage, and if you check most period photos, disconnect log cars always seemed to be endowed with oversize
flanges and extremely wide wheel treads. Metal wheelsets are also essential to lift the overall weight of these already “lightweight by design” cars.

To enable the Kato replacement wheelsets to roll freely in the MT trucks, use a small rat-tail file to slightly enlarge the bearing holes in the sideframes.
You will only need to give each bearing hole two or three licks with the file to do the job. Reinsert the metal wheelsets in the bogies and, once you are satisfied with the rolling characteristic of the modified bogies, set aside.

Another useful source for metal wheelsets are second hand Atlas metal wheelsets scavenged from old N scale cars. If you use Atlas wheelsets, you will not need to modify the trucks, as the Atlas axle lengths are the same as the molded MT plastic wheelsets. However, you will need to regauge the Atlas
wheels slightly tight in gauge. They have WIDE treads, and if they are left as is, they will rub against the inside of the truck sideframe and not roll
freely.

Incidentally, disconnects with tight gauged Atlas wheels seem to be a touch more reliable when running over PECO N scale points. Left gauged for N scale, they tend to “pick” the frog of the PECO points I use. I suspect that this is due to the wider than NMRA standard flangeways around the plastic guardrails as on the PECO points.

Body


The body of the disconnects, if such a small car can be said to have a body, is built of styrene and holds the bogie, couplers and log bunks together. Cut a scale 5′ 8 1/2″ length of 0.188″ styrene, and two 0.188″ lengths. Using CA, glue the two 0.188″ pieces together to form a 0.188″ X 0.188″ X 0.040″ block and glue this block to the scale 5′ 8 1/2″ piece exactly half way along it’s length. The 5′ 8 1/2″ length forms the “top” of the discon body and the block forms the “bolster” attachment for the bogie. Cut two scale 6′ lengths of the 0.060″ X 0.010″ styrene, glue them on either side of the body/bolster unit, flush with the top piece, and trim to length.

Log bunk


The log bunk is the most prominent part of the car. Cut a scale 5′ 8″ length of Brass 1/8″ channel stock and a scale 5′ 8″ length of 1/8″ X 0.020″ styrene strip. Using CA, glue the styrene to the bottom of the brass channel, and then drill a #75 hole vertically down through the centre of the entire bunk. You may use Grandt Line NBW castings to add detail to the bunk. My modelling friend built one master this way and then had white metal castings made, as we planned on building a number of these cars. I also found that the white metal castings were heavier than the equivalent Styrene/Brass master, and therefore contributed to the overall weight of the cars.

Assembly


Having made all of the sub assemblies required, let’s get down to business. Place one of the body sections upside down on the workbench, and using the
hole in one of the pre-prepared couplers as a guide, drill a #75 hole on the longitudinal centreline of the body. This hole will be the pivot point for the coupler, so make sure to allow for enough coupler swing. Do this for another pre-prepared coupler on the other end of the body. Once this is done, take a PECO trackpin and push it up through the coupler and body assemblies, and glue in place from the top using CA. Be careful not to let any glue get down under the top plate, or your coupler will be stuck in place and will not be able to swing. The trackpin head will hold the coupler in place. Using a track nipper, trim the excess trackpin above the top surface of the body, but do not cut it flush.

With both couplers thus attached, centre the body in all directions over the bogie bolster and glue in place. Use the axlebox journals and bolster spring details on the bogies as your guide, the MT truck bolster itself is molded off centre and if you use it as your guide, you will end up with a body extending too far off one end of the car. This step is critical because the entire balance of the car, not to mention the coupler operation, is dependent of the car body being level, centred on the track, and at the correct height.

You should now have something that looks like a disconnect log car, with couplers at either end, albeit missing its log bunk. At this point it is
prudent to check the coupler height using a MT coupler height gauge. Adjustments can be made by pushing the trackpin higher or lower in its body
hole and re gluing it in place. If you wish to, now is a good time to use your track nippers to cut off the trip pins on each coupler just underneath the coupler head. For exhibition work, I found that it is just one more thing that can go wrong. Most period disconnects were “hand braked” anyway and didn’t have airbrakes or associated plumbing.

A quick check of my photo evidence at this point revealed a sub frame of sorts surrounding some disconnects, acting as an end sill. There is a notch formed by the sideframe and the top of the axleboxes and spring bolster molding on each sideframe. Glue a scale 5′ 1 1/2 ” length of 0.020″ brass wire across the tops of the axleboxes in this notch on each side. Glue a length of 0.016″ wire across the top of the body end, between the coupler pivot pin and the end of the body, on each end. Once all glue joints are dry, bend the end wires as shown down to meet the side wires, and glue together to form the corners of the frames. These are fragile joints, so trim the excess 0.016″ wire away with care. I use a pair of track nippers for this job.

The last major job is to glue the Log Bunk onto the disconnect chassis. At this point you must make a choice. I prefer to glue my bunks straight onto the discon, thus making for a “low profile” disconnect car. Depending on your chosen prototype evidence, you will find some disconnects had “Hi rise” bunks. These can be simulated be adding appropriately sized wood, or styrene underneath your bunks before attaching them to the disconnect car body. This decision affects how the car operates when loaded. “Hi rise” bunks place the log load higher off the ground and therefore raise the centre of gravity of the loaded car, making it more unstable than with “Low profile” bunks. Either way, make sure you centre the bunk both fore and aft, and side to side. The appearance, balance, and operation of the car are all affected by the correct placement of the bunk. Use the spring molding on the sideframes as your guide.

Once the bunk has dried, drill a #70 hole as vertically as you can, using the predrilled hole in the bunk as a guide, all the way through the bunk, body, and if you have lined everything up correctly, the bolster hole in the MT bogie. If you build loads for these cars as described below, these holes will probably need to be opened up a touch to allow full 360-degree movement between the log load and the car.

If everything has come out as planned, you should be looking at a disconnected log car something like this. (I don’t have a scanner or a decent camera to show you my version, sorry!).

Finishing Touches


Feel free to detail this car as you please. The bill of materials lists “assorted small brake wheels”. I’ve used old N scale boxcar brake wheels,
small Roundhouse brake wheels, and metal detail castings. Disconnects were generally “hand braked”, so this is a nice detail to add to one corner of the
wire frame. Wooden “chock blocks”, (wedges of wood used to hold the logs on the cars), woodchips and bark, and chains/ropes/slings would all make good
detail additions. I generally paint my disconnects either flat black or grey as a base color, and then use “Oil wash”, (isopropyl alcohol and India ink), with pure pastel artist chalks and Tamiya XF series paints in washes, to create dust, dirt, and rust effects.

Loads


Creating loads for these cars is easy. Disconnected log cars were used all over the U.S. to carry logs from 8″ to 6+’ diameter and 16 to 50+’ long logs,
depending on the location of operation, and native species of timber available. My personal specimens average around the 3′ dia/22′ long variety.
Select a suitable size real wood twig and cut it to length. Select which direction on your log should be “Up”, by suspending it between two of your
newly completed disconnects. Most twigs will naturally want to sit in one direction. Flatten the first scale 4′ of each end of the “bottom” side of the
“log”, either with a knife or a file, then drill a #75 hole vertically up into the centre of the “log” around a scale 2′ from each end. What you are doing is creating a perfectly level bolster surface for the disconnect log bunk to ride on. Make sure that both bolster surfaces are level with each other, both in height and in horizontal plane. If they are not level with each other, it is as if you have built a bogie freight car with one bogie mounted on an angle.

Using either wood glue or CA, glue a PECO trackpin up into the hole, and once dry, use track nippers to cut the trackpin down so as to leave around 3/16″ – 1/4″ + of it protruding below the log. These pins should sit in the holes in the middle of the log bunks on your disconnects, thus providing the pivot points for the cars. As mentioned above, you may need to enlarge the hole through the disconnects log bunk, in order to allow for full rocking motion between the cars and the log load.

Disconnect log cars are a must have for any small “period” logging railroad. I hope these little cars can help you get that lumber out of the woods.

Happy Modelling,
Aim to Improve,
Professor Klyzlr
C/O Broughton Vale Tramway
Australia

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