I recently purchased a set of MTH Premier SP 2-car twin stacks. These are really nice. The MTH catalog and website lists these as able to negotiate O-42 curves. I have a 16 x 9 layout with a loop of MTH RealTrax, including all O-42 curves. However, going into a curve, these twin stacks bump each other where the “A” and “B” truck are coupled together in the middle of the cars, raise and turn slightly off the rails and occasionally de-rail. Is anyone else experiencing this issue and is there a solution?
It’s possible that MTH goofed by testing only the full 5-unit configuration. (Note that the units are conventionally identified as B-C-D-E-A, in that order, so that one end of the entire set is A and the other end is B.)
The angle that each unit makes with the shared truck on a curve depends on what’s at the other end of the unit. When the other end has its own truck, that is, when it is an A or B unit, it will make a greater angle than when the other end shares a truck with the next unit, that is, when it is a C, D, or E unit.
So, when you have a 5-unit set, the combined angles are least at C-D and D-E, and somewhat greater at B-C and E-A, whereas the greatest combined angles occur at A-B if you have only a 2-unit set. If MTH tested only the 5-unit set on O42, they may have erroneously concluded that the 2-unit set could also handle O42.
Sorry, running them on 072 and yards have some 054. No problem. My problem is the old MTH coupler uncoupling under a heavy train behind them. Thus the little rubber bands that Orthodontist use for retainers slipped over the coupler “spring”.