Over the years I have acquired several Y6B mallet 2-8-8-2 steam locomotives made by Rowa. First produced in 1969 these are beautiful models and run like sewing machines, even by todays standards. My only issue with them is the motor which, in my opinion, is underpowered for such a large locomotive. My solution to this is to run two together at the front of a long train, as the railroads often did. The problem with this is the front coupling is a dummy knuckle coupler and is purely cosmetic. In this post I wanted to share with you how I overcame this.
These mallet locomotives where first manufactured by MRC/Rowa, then Charmertz/Bemo and finally by Con-Cor/Rivarossi. They were also released by Con-Cor/Rivarossi as 2-8-8-0 EL-5. Despite minor improvements over the years the main model has stayed the same, here is one sat on the turntable at the roundhouse on Bob Norris layout Somewhere west.
Micro-Trains do offer a conversion kit for this locomotive, No 1048, but all this is is a pair of body mount couplers and you need to cut your own hole in the pilot which can go very wrong.
The pilot on the front, as well as having the coupling, also carries the headlight. The whole assembly, as shown below, is made up from eight parts which includes the main body, handrails, dummy knuckle coupler, front cylinders and headlight, two plastic valve gear bars, clear plastic light corridor and a metal nut used to bolt it onto the locomotive. The dummy knuckle coupler is not shown (it was missing on this particular locomotive).
To remove the pilot you will need to first remove the front set pilot wheels. With the locomotive upside down remove the plastic plug holding in the front wheel set, this usually has a whisker of plastic running passed the wheel set to give it some springiness, again on this particular model it is missing.
The wheel set then simply lifts out.
The newly exsposed screw holds the pilot in place.
Once removed the whole assembly will slide off.
The assembly then comes apart very easily into the seven different parts. Although I have found out that the very early versions had this assembly glued together and are very reluctant to come apart.
Once I had all the parts separated I set about drawing a 3D model of the main pilot section. My original intention was to make a replacement part that had a socket to receive a Micro-trains Z scale bodymount coupling. With the 3D model complete and successfully uploaded to Shapeways I ordered one and as usual within about eight days it arrived on my doorstep. With this first test print it quickly became apparent that I had incorrectly measured the original because as you can see from the image below the steps are smaller than the original on the left. But this is the reason why I test print everything.
Although the steps were the wrong size I was still able to experiment with the pilot to see how the Z scale coupler fitted. Although it did fit well I do find the Z scale couplings really tricky to put together and I felt that it looked too small on such a big locomotive. You may have also noticed that the cow catcher bars run in a different direction, this is because I used the same 3D model parts I have already drawn for my Atlas 2-8-2 replacement pilots.
So taking all that into account it was back to the drawing board, or at least the laptop. I first fixed the issue with the steps and I also refined a few other details. Because I wasn’t keen on the Z scale coupling I created a new version with a pocket to accept the N scale Micro-trains body mount coupling and added horizontal cow catcher bars.
The test prints this time came out fantastic, shown below are the two pilots either side of the original. Z Scale coupling on the left and N scale coupling on the right.
To reassemble the pilot, first the handrails need to be secured. The front two pegs clip into the new pilot and the rear tabs fit under the walkways as shown below.
Then the cylinders fit onto the main body and the plastic light strip is inserted into the rear of the headlight.
The last part to add was the actual coupling. This slides in from the front and is secured by a screw. The standard screw which comes with the body mount couplers is too long and would protrude up through the pilot if left as it is, so I cut it short with a pair of side snips. Please use safety goggles if you are going to do this as the ends fly all over the place. I left about 2mm (0.078″) of the screw protruding from the coupling, the coupling will need to be installed before the screw is fitted.
Next came the actual test fit onto the locomotive and as you can see below it went well.
The final test was a coupler height check and for this the locomotive is put onto the track and coupled to a Mocro-trains height gauge.
This same set of checks were also carried out for the pilot with the Z scale coupling and again, as shown below, it all lined up.
So using the N scale pilot, my preferred coupling, here are two Rowa Y6Bs coupled together.
Now I know that the 3D printed pilots work all that is required is a coat of pain. I used a simple matt black acrylic paint and the finished locomotive looks like this.
Normally when I show a new product I also share with you where you can get it but this week I need to do one more final test before I am happy to release the Rowa Y6B replacement pilots, and that is a full running test on a layout with curves and inclines. This is to check that the Micro-trains bodymount coupler does not interfere with the leading set of wheels as they are very close. So in a future post I will have some more pictures, maybe some video and I will let you know where you can purchase your own.