06 August 2009

Buses will replace trains...


All the enthusiasm of the previous post quickly evaporated. Flushed with success from getting my three-car DMU round without suffering from the gradients, I tried a five-car loco-hauled train using a variety of locos. Every time I ran the test, it failed on the inner loop. Not one of my locos can haul a five-car train up that slope. Wheelslip kicks in, and everything gradually grinds to a halt. On the outer loop, where the gradient is less severe, the trains make it up more or less comfortably. But this layout has two loops and both have to work; at the moment, one of them doesn't. Hmmm. (And it's not as if some people didn't warn me this might happen!)

Various options have sprung to mind as I've pondered what is effectively a roadblock:
  1. Soften the inner loop gradient. Unfortunately, there isn't enough space to make an appreciable difference, so that option is more or less ruled out.
  2. Reduce the likelihood of wheelslip. This could be with rubber tyres on the traction wheels, or somehow making the track less slippery. I don't know how much effect that could really have.
  3. Have mechanical assistance, such as rack and pinion, to help pull trains up the slope. Apart from looking unsightly in the uncovered track sections, this would mean fitting every loco on the layout with traction pinions - not easy.
  4. Push trains up the slope with a tail loco. Not really practical as the loco would have to detach and return with the train still in motion, to avoid emerging from the tunnel and spoiling the illusion.
  5. Re-route the inner loop, as suggested by friend and fellow modeller Alan at Rio Grande. There is a loft cross-beam about 3ft from the front of the layout, which could be used to support an extra track with a gentle gradient, carrying inner loop trains from F1 round to F5.
The last option requires the most engineering, including building about 20ft of new trackbed and remodelling the station throat on F5i-B5u. But despite the delay to track-laying, I think it's the most comprehensive solution. I won't remove the existing inner loop and may try softening the gradient a little bit in the hope that at least some trains can use it. The station approach on F5 will look as if it has two mainlines merging - it will be a simple double-track crossover junction. The new line will disappear into a tunnel, cross over the outer loop on F5o, and then run round the loft beam gently losing height until it reconnects with the inner loop somewhere under the recently added F1 sidings. The new loop will be single-track, and covered, I think, for protection and to hide it from view. In time I might add some storage sidings on the loop if I need to relieve pressure on the lower level under the station.

It's a setback, but actually the operational potential of the new loop is rather interesting so it might be a blessing in disguise. The only trouble is, with the holiday season in full swing I don't know how long it'll be before I can get the work done.