This page is my third SBB Ae 3/6 II page. All may be seen at the Models page. Additional search words: CFF Ae 3/6 II, SBB/CFF Ae 3/6 II.
Curve overhang
SBB Ae 3/6 II: Roco 68402 10403 (left, there) and Märklin 37512-2 10456 (right, there) in track radius 286 mm (11.5 inches)
Märklin and Roco take completely different compromises to allow the locomotoves to operate on the not to scale curves of the track. When it comes to running through curves the compromises seem to be:
- Roco applies power to one axle, Märklin to all three, with tooth wheels between them. So Märklin probably operates long before stopping on more uneven or dirty tracks. It’s like a 6 wheel drive! However, overhang is enormeous, since the free moving of each axle across the locomotive is little. The larger overhang of the Märklin body may also be seen by the large disalignment of the buffers. See picture (right)
- Power on one axle allows Roco to build the three large wheeled axles more flexibly. There is a kind of bogie inside the three axles, giving the row of wheels more flexibility to follow the track. The overhang is almost none. See picture (left)
- So, Roco can make the ladders as long as they should be, where Märklin must stop them above the smaller wheels.
- Of course, all wheels follow the track, but the body on top will position itself according to the forces of the structure below. The more snaky structure below, the more the body will follow. Provided the forces in the front and in the back become well balanced as the locomotive takes the curve. Both ends should pull the respective part of the body back on the track with the same strength.
- Update Dec2022: the Roco 78293 (#10412) with sound has exactly the same nice frame and wheel design as the older 68402 (#10403). See here
For nice curve operation, Roco wins. (For uneven or dirty tracks, Märklin wins.)
The above picture is also used here. The interesting thing is that the Roco followed the curve so nicely that it passed the catenary mast; it was when the Märklin loco passed that it stuttered at that place.