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About jtlan

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  1. I was initially concerned about this as well; however, on the Umbauwagen 3yg the front and rear axles always turn together. The three axles are in a straight line in the middle of an S-bend, which works because the track is approximately straight there: For a wheelbase of this length (20 studs axle-to-axle), the deviation is small enough that the wheel flanges don't rub on the track (Try it and see! Big Ben Bricks wheels are slightly thinner and so are affected less.). The articulation is mostly needed to reduce friction in turns, and to keep the wheels from riding up the point or guard rails of a switch.
  2. FS 207 - Badoni / Breuer type IV

    I didn't know Breuer tractors were made under license. They seem to be much beloved across Europe! I previously modeled a Breuer Type 3, but its small size at my typical scale kept me from motorizing it. Since you need a separate car for batteries, maybe it would make sense to motorize the auxiliary car instead?
  3. Wagons for DR Class 99

    How cute! One of the prototype photos you worked from is the same one I used for this MoC -- it's always great to see another interpretation of the same prototype.
  4. Wheel slippage

    Almost certainly it's a weight issue, unless looking at the tires you see wear. I'm not familiar with off-brand track, so it's possible that the track itself is wearing, leaving dust on the wheels and reducing friction. If you don't see any dust looking at the tires, put something moderately heavy (the battery box) on top of the car that has the motor, and see the motor continues to slip.
  5. LEGO Train Bogie Problem

    If you have a train of multiple cars, you could rigidly attach the outermost axles to the bodies of the outermost cars, then connect the inner axles in pairs to form bogies: Sort of like Jacobs bogies in the middle. The long distance to the outermost axles might still cause problems, though.
  6. L Motor Freezes

    Power functions trains usually require a certain amount of mechanical expertise and fiddling, so the problem may not originate electrically. Would you mind posting pictures of your design so I can assist in debugging? One other thought -- disconnect the motors from the model and try running them. Do they still seize? What if you load them lightly (by grabbing the output shaft)? If so there may be an electrical issue; otherwise, I'm inclined to believe the problem lies in the design of the drivetrain.
  7. Hello CaL, In most photographs of the actual locomotive, the rods are some grey metal, but with the inside of the web painted red. While the Technic half-beams are somewhat rare in red, they do exist, and so I could have used red rods for this locomotive. However, I wanted to make sure the rods were easy to see, particularly while the locomotive is running. The large wheels are official Lego wheels. The small wheels are from Big Ben Bricks. Lego also makes small red wheels, but they are slightly thicker and I would have had to design some parts of the model differently. An extended musing on point 1, above: I think it's important to keep in mind that, as builders, we are building a model of a locomotive, not an actual locomotive. Therefore, it's important to take into account the setting in which your model will be seen. For example, in most cases the model will be seen from slightly above -- design your model knowing what will and won't be seen from that angle. Parts of the model may blend together from a distance -- you might want to choose colors that make those parts stand out. And so on.
  8. [MOC] Umbauwagen 3yg

    Not much of one for painting or discoloring. If the Weinstrasse variant is out of my budget, so be it. The coaches were built after WW2, so a wartime paint scheme would be highly anachronistic. Dark grey is also a very rare color for the window.
  9. [MOC] Umbauwagen 3yg

    Not sure what you mean by "robust", but the linkage features Technic axles reinforcing the sections above the outer axles and three stacked hinges in the joints. It's extremely unlikely to break under normal operating conditions. Thanks! I'm really proud of the mechanism. This model has been over a year in development, if you start counting from the first experiments with the 4+2 arrangement...
  10. [MOC] Umbauwagen 3yg

    No issues whatsoever that I could find. After I worked out the basis I built a test chassis and sent it around a test track as fast as I could. A 9V train motor could pull it at its top speed without derailing. In reverse, the car could be pushed up to very high speeds before coming off the track. Thank you for that information, @RogerSmith. Most of the maintenance cars I found were painted yellow, with the blanked-out windows you mention here. The Deutsche Weinstrasse color scheme is another possibility ... but tan windows are extremely expensive!
  11. [MOC] Umbauwagen 3yg

    Greetings, Train Tech! About a year ago, I posted my Umbauwagen 4yg. Here is the 3-axle variant, the 3yg: The name Umbauwagen means "rebuilt coach" -- these coaches were built after World War 2 by modernizing prewar compartment coaches. More accurately, this is an AB3yg (first/second class) + B3yg (second class) pair -- these cars were nearly always found in close-coupled pairs. A few survive as single units in work trains, painted yellow. The body of the model is essentially constructed the same way as my 4yg model: studs-up construction for the main body (leveraging the train window and the 2x8x2 curved slope), SNOT construction for the doors, the details around the buffer, steps, and corridor bellows. Of course I designed new side frames, and there are a few minor details that are different such as the lights above the end doors of the pair. These cars were painted green in DB service, but as the train window does not come in green I elected to build the 3yg in a different color scheme. I believe that this livery corresponds to 3yg cars used as trailers for the ET 85 electric units -- someone with more knowledge of German railways may be able to shed more light on this. At the time I built the 4yg I also built some test models to research how feasible it would be to build the three-axle variant. However, I ran into difficulties designing the chassis and moved on building the 4-axle variant instead (which had none of these challenges). Earlier this year I circled back and spent some time looking into the problem. The first attempt was to articulate the chassis as 4+2, pivoting the body to reduce the overhang -- a technique I previously used on the tender for my model of the Gr670. However, the Umbauwagen 3yg not only has a long 3-axle wheelbase, but also has a long distance between the outer axles and the buffers: Articulating the chassis as 4+2 would allow the car to negotiate turns, however it would also derail any vehicle attached to it as the buffers swung out widely. Further iteration yielded the general outline of my eventual solution: The center and end axles are connected together with a 6-bar linkage, rather than a rigid frame, allowing the chassis to change shape when traveling through curves. It's important to note that the center axle is actually what actuates the system. As the car enters a curve, the center axle is pushed sideways to follow the curve, which in turn angles the outer axles to follow the curve as well. The track cannot apply rotational forces through a single pair of wheels on one axle, and so a similar design to this one without the center axle would not work. You can see the mechanism here: The outer axles are mounted on 2x2 round bricks riding in a 2-stud-wide channel, allowing them to turn and slide slightly towards the center of the car in turns. I experimented a bit to find the best places for the pivots and a construction that would be light and reliable. In the final model I removed the blue tiles shown in the screenshot, to avoid additional friction and binding in the mechanism. Thanks for following along! As usual, I've uploaded some additional images to a Brickshelf gallery, including some notes on and prototypes of the linkage mechanism. Thanks for reading, and let me know if you have any questions!
  12. Hi CaL, Thank you for the suggestions. However, I'm mostly a purist builder, particularly where electronics are concerned, so I'm happy to use the stock components. I enjoy the constraint of working within the system,and even (particularly?) the challenge of fitting the PF components within a small model. I think a builder can grow a lot by learning and building within constraints, rather than using a third-party solution to "fix" a "problem". Cheers, ~jtlan
  13. Given how small I usually build, this was actually a very comfortable change of pace for me! Still, the shape of the locomotive dictated parts of the layout -- for example, I didn't really have any room to put the battery box in the locomotive itself. Definitely, with this locomotive (and TP56 before it), I thought a lot more about "usability", both in terms of reception as well as battery box accessibility.
  14. Thank you, everyone! I always test the chassis before I get too far along. The drivers display the maximum spacing between axles I'm comfortable with. Thanks, I'm pretty pleased with how the tender came out too. I had to do a partial redesign at one point, as I realized there was no way to get the battery out or to turn it on/off! This isn't the first time I've used that technique. Genealogy of ideas: @Commander Wolf demonstrated it to me after noticing it on @SavaTheAggie's T1. It's wonderfully compact!
  15. Possibly the geometry is off -- are the leading and trailing trucks free to rise and fall a short distance? Failing that, did you quarter the drivers correctly?