The spiral.

The spiral represented schematically.

Module A houses a spiral tunnel that connects various parts of our layout but is also used to overcome the large difference in height on a small surface. This spiral tunnel has two parallel rail spirals. The inner spiral brings trains from the shadow-station to the station of Alp Grüm or visa versa, This makes the largest difference in altitude. The outer spiral runs from the station of Alp Grüm to the station of Campocologno or visa versa. Both spirals are single track and used in both directions On the drawing on the left, you can see how it is put together and also which level exits where. One thing is not in the drawing; there is another passing station in the outer circle. Also the line "to shadow-station" splits and the split-off goes underneath to the other side of the station of Campocologno. The point where the two split is not only the way out of the shadow-station but also the way in. This makes our layout into an 8 shape, just a little bit twisted. One circle being the shadow-station and the other the rest of the layout.

The red arrows in the picture point the place where the train leaves the outer ring towards the station of Alp Grüm. They will return to the spiral on the upper level but now on the inner circle.

The picture shows the spiral tunnel, seen from the back. All tracks in the tunnel are protected by plastic strips to prevent trains from falling off. This plastic is flexible enough to be able to put your hand between the levels of the spiral. Its approximately 3 mm thick and is also used for isolating doors in factories and trucks. The spiral is built of half circles made out of 9 mm multiplex that are connected with metal strips. We chose these strips because they are small and thus need less height. They are placed beside the rails so they also can't interfere with the pantographs. Connecting the parts with wood would leave less room for the trains and thus increase the gradient of the spiral. To make the gradient smooth and adjustable we use threaded rods through all levels. One row (of 8 ) on the inside and one row on the outside of the spiral. Now you can mount the wooden levels with a screw below and above, very accurately.

During construction of the spiral you have to mount the parts (half circles) one by one over the threaded rods and put the rails on them right away. If you don't put the rails on per half circle you can't reach them anymore to fasten them. Its a lot easier to do this part by part. Then adjust the gradient and height per circle later on, when all parts are mounted.

Back to the top.

Back to the model layout overview on the introduction page.