jim s-w wrote:Can you power both Axles Russ?
I think that would be very unlikely in that particular design, Jim, because a through transmission axis would get in the way of other key bits of the bogie. The design is, primarily, one to see if an endframeless approach is feasible.
The point you make about most prototype second gen DMUs having a powered bogie and a trailing one is interesting, but begs the question whether we need to replicate the prototype approach at all. Driving only the inner axle of two bogies of one model vehicle makes sense in terms of vehicle weight-distribution, and is generally sufficient traction-wise. That's a Ted/Bill valid point of view, and I'm not criticising it. A significant factor in the endframeless pinpoint design is the amount of weight that can be put over the bogie. One could say it doesn't follow a true second gen approach, but then one could say that approach is really only followed properly with axle-hung technology, which is what Ted would be thinking of as the 'proper approach', particularly for multi-driven axles in modern EMUs. I rarely give a fig for such fidelities myself, and am a fan of single twin-axle drive bogies, because only one bogie frame needs significant modelling work! Quite a few years back, I knocked this up from a Bill B4 frame:
This is intended to be a single heavy (100g) drive, with parallel-ended axles and bearings for safety, of a 4-car unit. (There's no point in worrying about bearing friction on driven axles.) The complication is of course the transmission tunnel obscuring a conventional bogie mounting, and although I solved that to my satisfaction (a special shouldered bolt), and got the whole unit including the secondary spring plate within a 15mm headroom, I don't think Ted or Bill were sufficiently enthused or thought it was sufficiently 'productionizeable' at that time. The irony is that my twin-axle drive is intended for a 1st gen unit!
Ted and I argue about our mutual inconsistencies and compromises till the cows come home...
I'd like to think we're not quite as inconsistent as Bachmann though, with the initial trepidation over their 108 drive, getting cold feet about its traction and weighting it down with that absurd 400g mazak chassis, then going completely over the top with the monstrous 150 ("look, no interior!") drive, and then in a fit of strange confidence, putting the 108 drive in the marvellous 4-CEP to rapturous applause.