As I said, I was manager for this project and worked very hard with it for two full years.
I don't want to tell anyone what or how they should do, but in best case, I can contribute with a different view.
I have hundreds of drawings on these locos, but right now I don't know how to show them, any suggestion?
I had Photobucket earlier, but not any more...
I tried this on a Swedish site for forum pictures, but they "adapt the pictures for best viewing experience". Which literally means that I can't show detailed drawings this way. I have uploaded them in much higher resolution than what is shown.
Our choice of the TU4 instead of the more modern variants was based on its definitely much better classic look and furthermore the width over the frame is only 2080 mm (82"), which fits precisely in our profile. But the cab had to be rebuilt (original design of the type was with this more narrow cab).
The drawback of this type is that the design is 60 years old. It is centred around a gearbox with torque converter, two mechanical gears with separate electro-hydraulic clutches, reverser and transfer gearbox. All in one two ton massive unit. Specially the TU6 has a much more compact reverser/transfer box separated from the gear box.
As all Russian designs it is built for very rugged service from the desserts of central Asia to the arctic winters in Siberia. But it is a bit "rough". Not a sewing machine precisely.
As I mentioned the true core of these locos is the design of the trucks. They are extremely simple and well functioning. As you may see the frame is made up by two rugged beams with square cross section (made from two U-profiles), placed right over the axle boxes. The only suspension is the coil springs between the axle boxes and the truck frame. The loco frame rests directly on the four low friction pads seen in the top view. The pads run in oil baths. The king pin takes no vertical load. This means that at low speed there are no centring forces on the truck, it is free to rotate according to a less than well maintained track.
At higher speed, on the other hand the trucks have enough friction so they won't move. This would give rise to unacceptably high flange and track forces. If it was not fitted with the ingenious Meste axle box. The axles are free to move axially in the boxes and are centred by coil springs at the ends. The movements take up all small track irregularities at speed.
The loco literally floats along the track like a modern tourist coach with air suspension. There is the potential risk of instability with coil springs only, thus the trucks are designed to have shock absorbers. But those are not needed and have never been used anywhere.
This is what I managed to upload on our loco:
We had a never used Scania 9.5 litre, six cylinder in-line, turbocharge diesel with 200 hp donated to the project by the maker.
(We have about 10 coaches and freight cars built by them on our railroad.)
