will a riverossi 4-8-8-4 big boy run fine on 18* radius track, i have one that hasn't been ran in forever and all i have is 18* radius track the driveshaft keeps coming out and it doesn't run well, not sure if it has anything to do with the radius or not, both the 8 wheel sets swivel so i'm really not sure myself.
the drive shaft is proably popping out because of the radius. according to my sources, the largest engine expected to perform well on 18" is a 2-8-0
The BLI Hudson 4-6-4, the Bachmann Spectrum Decapod, and many other engines larger than a smallish 2-8-0 (the IC had huge 2-8-0's) can run well on 18" curves. I know nothing of the Rivarossi BB, but would guess that it would be a bit of a tight squeeze. For sure a large-drivered Northern 4-8-4 in HO, even in plastic, would almost certainly not be able to run on 18" radii, except for (I think..) the Spectrum J Class 4-8-4 from the N&W. Usually a steamer will derail before anything breaks, but maybe the drive linkage, if plastic tubing, has become brittle with age?
I have a couple of Genesis Big Boys in HO and they definitely do not like 18" radius curves. In my case, they bind up and slow down in the turns and derail if a switch is anywhere near. I have no idea why the Riv BB pops the driveshaft but it might be the 18" curves. Minimum radius required for steam locomotives isn't so much controlled by the number of drivers on a rigid frame but the wheelbase of those drivers. Early 2-8-0 and 2-8-2 locomotives had drivers that were less than 60" in diameter. When set close together, this produced a much shorter wheelbase than the later locomotives like Big Boy and the 4-8-4 of the 1940's. Big Boy has 68" drivers and UP 844 has 80" drivers. This makes for a long wheelbase for a set of drivers on a single frame and means that curve radius has to increase - unless some of the drivers are flangeless or have a lot of built in side-to-side movement.
4-8-8-4'a don't like 18" curves As I said last time, Most older HO engines are supposed to go around 'standard' 18" radius curves on factory made track. Only the latest $550.00 and up engines require a larger more scale radius track. The real Big Boy engine was designed to take a fifteen degree curve, which in HO Scale would be 52" radius !!! Only induatrial engines and some logging tea kettles could negotiate the 18" HO curves. If the drive shafts fall out, it should be a hint that the radius is too tight. You may have noticed the front and rear trucks are off track and the tender has tipped over too. It is no problem, jost back up and go around another curve some where. Don't feel bad, it took me 79 years to learn that, and yes I did work for NASA. HA!
ok, i'm assuming life like snap track is 18" radius, at least the standard stuff that comes with a set. the engine, was a used engine and bought as parts along with 2 other engines. i have a 2 mantua 4-6-2s a mantua 2-8-2 and a ihc 4-6-2 that runs really smooth. they run fine on the track. but the bigboy was bought as parts and the motor was changed with a can motor that i'm pretty sure didn't come with it. so theres a chance the shaft on the motor isn't long enough or something is wrong there. the driveshaft does hit the body when it turns but i have it moved as far out rite now to keep it from popping out. but it still does. i didn't know if this could be the track or just a poor motor swap job so i posted the thread. thanks for the replys, i'm still not sure. the trucks don't come off the track and the tender doesn't fall over. nothing ever derails, the driveshaft just pops out and it's a pain to put back in.
OK, I understan d the problem now. When the motor was switched, they didnot mount the end of the motor shaft in the same position as the Rivarossi motor shaft was. So, you have one of two choices: either fix it, or fix it. Let's take the first one, its easier. Carefully rip the thing apart so you can get to that pesky drive shaft. Look it over carefully and note how they mounted the new motor. If the just glued it in place, it might come off by sim ply cutting with a knife. If the did some surgery and drilled mounting holes for dcrews, then we may "have a problem Houston!" (If this motor is powerful enough to suit you, keep it. That makes this easy.) Set the chassies on an 18" radius curve track and see if any of the drive shaft touches the motor shaft, make a note of how far if there is a gap.
I just found out there are Drive Shaft kits already on the market! N need to go through making one from scrap, just buy one to fit your shafts
