Ha! Fooldja! Yeah, the question really is about hunting, though, the kind steam locomotives occasionally do on their way down the track as they surge from side to side. I notice in some videos that sometimes 1:1 scale locos ‘hunt’ back and forth, but that others don’t. Does anyone know if this is a factor of adjustments made (or not made, as it were) to the drive train?
What prompted this question is actually a model railroad situation: when I trotted out an old HO 4-4-0 just for the enjoyment of watching it the other day I noticed it, too, was ‘hunting.’ My instincts tell me that, as with a 1:1 scale locomotive, I might be looking at an adjustment or ‘balance’ problem of some sort (maybe a quartering issue??). Anybody ever deal with this before? I’ll be grateful for and interested in any observations, comments, advice, etc. Thanks!
If a model locomotive is “hunting” from side to side, it probably means the wheels are out of gauge. Check with an NMRA gauge and I’d bet you find they’re too narrow. Widen them out a little and it should solve it.
On the prototype, a short wheelbase might be a problem that would cause hunting…or poor track??
In steam locomotives, “Hunting,” (also known as, “Boxing,” for the sharp ‘punching’ movement, and ‘dynamic augment,’) is usually associated with the asymmetric thrust characteristics of the beast, sometimes augmented by sloppy fit of axle boxes. In models, it can be the result of binding due to drivers being just a tad out of quarter.
Four-drivered locos and those without lead and trailing trucks are more prone to ‘hunt,’ but even the largest locos actually feel the same stresses.
I think that “hunting” is the wandering movement of a loco, any loco, that results from bad track and (possibly) bad bearings or other mechanical things while “boxing” is the specific punching action seen on usually short wheelbased rod coupled steam locos. Either can cause the loco to derail.
Any stock can wriggle in the same way as a hunting loco… and for the life of me I can’t recall the term we use for it. I have seen a whole train of old stock waddling down the track like a demented slinky spring. People spend hours getting their models to ride straight but the real thing can shimmy all over the place… and it can do it on near perfect track.
Bad track will make everything shift around in pretty much the same way.
I was on a train once that hit some track that must have been near saturated. Whether the loco didn’t ride badly or the driver just held on an prayed I don’t know but the carriages got pretty close to their natural wave motion. As we were doing about 80mph it made life interesting. I didn’t pull the cord or even move as I figured that any sudden change could be as disastrous as keeping going. Eventually we got back on good road and everything settled down. There were a lot of very green passengers.
One of the factors in the success of the Norfolk & Western “J” class 4-8-4s was that they had relatively stiff springing on the lead and trailing trucks which controlled the side-to-side motion of those trucks. This helped create a more secure “base” which was less prone to “hunting” and also allowed the attainment of relatively high speeds with comparatively low (small) drivers for a passenger locomotive.
In excursion service, this springing had a different effect when it was found that the J 611 did not do particularly well on “Y” tracks that were set up for diesel locomotives. At least one derailment occurred as a result, and care had to be made on selecting routes which allowed turning of the locomotive.
So, the behaviour of the locomotive is not just a factor of the thrust of the cylinders or the rigid wheelbase of the drivers, but is also affected by the design or set-up of any lead or trailing trucks.
Thanks everyone, for your responses and info. I wasn’t even sure that anyone would recognize what I meant by ‘hunting.’ I heard a term for what I was talking about a long time ago, but I don’t recall that ‘hunting’ was the term I heard. Anyway, you understood and I thank you all again!