LogginLocos Perhaps your not considering the way two race cars on the same loop of road tend to be quicker on The inside opposed to the car on the outside
Perhaps your not considering the way two race cars on the same loop of road tend to be quicker on The inside opposed to the car on the outside
It isn't a substantial factor due to the conical profile of the treads of all wheels on rolling stock. As the item enters a curve, even a really sharp one, the axle shifts outward to bring the flange on the outer wheel closer to the rail's flange face. In doing so, the diameter of that outer wheel increases somewhat due to the conical shape. Meanwhile, the inner wheel's tread has diminished commensurately. On that fixed axle, the now different diameters of wheel accommodate the difference in speeds required of a cast axle/wheel assembly, with the two wheels being the two race cars you mentioned.
wobblinwheel Not sure I entirely understand that. It seems that looking at one side of an articulated loco, and the EXHAUST is pretty much in sync, couldn't one set of drivers be, say, 180° out of position to the other set, yet the exhaust still be "in sync"? You don't mean that if the front engine is "rods down", then the rear drivers also have to be rods down in order for the exhaust to be synchronized? If each engine group exhausts 4 times per rev, that changes the opportunity for "exhaust synchronization" considerably! It seems that one driver set has four positions per revolution for the exhaust to actually be....."synchronized"? I think I noticed that several times in the videos....
Not sure I entirely understand that. It seems that looking at one side of an articulated loco, and the EXHAUST is pretty much in sync, couldn't one set of drivers be, say, 180° out of position to the other set, yet the exhaust still be "in sync"? You don't mean that if the front engine is "rods down", then the rear drivers also have to be rods down in order for the exhaust to be synchronized? If each engine group exhausts 4 times per rev, that changes the opportunity for "exhaust synchronization" considerably! It seems that one driver set has four positions per revolution for the exhaust to actually be....."synchronized"? I think I noticed that several times in the videos....
I agree.
There are 4 positions for one engine to be in so that it will have a matching exhaust for the other engine.
And then there's "real close": What would 1 degree off sound like? 2 degrees.......?
I expect that the above would sound very much like a "regular" locomotive.
What would a "totally out of synchronization" version sound like? I'm talking about when the engines are exactly 45 degrees off. Would it sound like a regular engine at twice its speed?????
It does seem that it would be very easy to have a sound decoder where you could program the "phase differences" in.
Please note that what I'm describing is a continuous sort of thing. That is, the locomotive is happily moving along, not slipping. If that's the case, the sound shouldn't be changing its cadence much, at all.
Way back, my gripe was with the programmed sound that has a permanent cadence rotation--it goes back and forth from "in sync" to "out of sync". ALL THE TIME. Aside from having different driver diameters, front and rear, I don't see how that would happen.
Hmmmmm.......:
I just ran some numbers, and it's not at all inconceivable that that sort of thing happened (having different driver diameters front and rear). Consider that the front engine of a simple articulated has the reputation for slipping more often than the rear. Each slip will wear a bit of the driver tires on that engine. With enough slips, the wear will add up to a smaller driver diameter on the front engine. And, as I said, the numbers I just ran seemed to fit with the sounds I heard emitted by the HO articulated I was listening to. If I were to hear it again, and measure the track distance between "in" and "out", I could calculate the different diameters.
OK.
So then a person could ask: How often and for how long does this situation last? For any batch of articulateds, how many of them will have this "affliction"?
Beats me.
That's something else it would be neat to be able to program at different levels.
It does seem to me that the diesel sound setups have a lot more sophistication than the steam. It is time to change that.
Ed
I put a Tsunami sound decoder in my Athearn Challenger, and it has settings for "slow, medium, and fast" for the chuffs to go in and out of sync. Even on "slow", it happens too often, and with PERFECT regularity! It would be nice to just have a function key to disable the double-chuff when running on the mainline. It's just not logical that they would slip out of sync once every mile!
Mike C.
A bigger problem is decoders that only do 'out of synch' for articulateds, essentially just doubling the chuffs at the same set time difference. That's very unrealistic.
An articulated engine is actually two separate engines sharing one boiler...really not much different than two smaller engines double-heading. The two sets of drivers are going to be in synch sometimes, a little out of synch sometimes, and way out of synch sometimes. In a simple articulated, where all four cylinders' exhaust goes up the stack, you're going to hear all 8 chuffs per revolution, although sometimes they will be 'in synch' enough it will just sound like 4.
Remember, the two engines' wheels aren't connected to each other. I've seen say the rear set of an articulated engine's drivers spin out when starting a train, while the other set doesn't. It only takes a little slip of the drivers to put the engines out of synch...or one set of drivers being slightly more efficient than the other set at using steam, maybe because one set of drivers has slightly more lubrication so it runs a little faster than the other set. Even if it's a tiny amount of difference, like 1 mm. each revolution, it's going to add up over miles and miles.