not attempt to side track the thread....but it seems like a place to get the need information:
quick question--to reduce gearing in steam locomotive, or any locomotive (I suppose) does one increase the number of teeth/gear, or reduce the number of teeth / gear...and it is the gear of the axles as worm gears are standard in their gearing?
thanks for any help!
sincerely
Gary
There are some common things across many engines, like the bore size and gear ratio, but in general,
gear changing is a can of worms. Some things fit other engines, and some don't, and there is no
"standard" for any of it.
While there are some gears that are common across some engines (for example, a lot of Kato diesels have very similar sized gears in them), there are no guarantees, especially when it comes to steam. The worm and worm gear on a Trix K4, for example, isn't the same as the worm in a Mikado or a Spectrum 2-8-0, and so on.
Second, to reduce the gearing, you need to either increase the diameter of one of the gears, or increase the number of teeth.
(At some points in the geartrain, like on the small side of a double gear that goes to the driver gears, you could
actually reduce the size of that small side, but it would be almost impossible because the diameter is already
very small).
The idea is that you want the worm to have to spin around more times to get that other gear to go around ONCE.
So that ends up meaning that the
motor has to spin more times to get one revolution of the gear it is mated to, and thus, ultimately, the wheels will turn slower for a given speed of the motor.
It is not always easy to do either (increase the diameter or the number of teeth). In fact, it's darn hard in most cases.
The tricky thing is that if you change the worm and its mating gear, now you have to change the idler that mates with that, and then you have to change all the driver gears. Finding those, even by measuring and calling NWSL, is not easy,
and the actual work of pressing gears off axles and getting all the bores and positions right is also not easy.
My preferred method is to forget trying to change gears, and instead, use a motor with an additional gearhead to
achive more reduction before you even get to the worm. The Faulhaber or Maxon motors I like to use can be fitted
with in-line 4:1 gearheads. So now you get a 4x reduction just by changing the motor.
That comes with its own problems.
Sometimes it's not easy to make the motor fit. Sometimes the output shaft isn't 1.5mm, so you have to either
grind down the shaft or bore out the worm to fit it on. But all in all, the results are terrific.
The other big benefit is that the Faulhabers and Maxons generally have a lot more power and torque than
a conventional motor. There are exceptions, meaning there are some weak coreless motors out there,
but the serious ones from those two brands are usually brutes. And of course, they ain't cheap. Retail prices
are $75 and up, PLUS the gearhead, which often doubles that number. But you can get a much better deal
if you go to motorman (
www.micro-loco-motion.com, or look for his motors on ebay).
I bet that's more than you wanted me to blather on about.
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Chris,
Thanks. Yes, I see rods and pieces on eBay. I think I would like to get my hands on some really thin tungsten
sheet (like .010") so it can actually be cut without too much agony, and so that thin sheets can be stacked and otherwise placed inside boilers to add weight. It's expensive on-line (about $50 for a 6x6" sheet that is .012" thick).
There seems to be some leaking out of Russia and the Ukraine on eBay. Maybe...
Mark:
Yes, I'm pondering an NP 2-8-2, but I want to work out the details of the chassis and motor before I worry about
the cosmetics.
At present, I have it remotored with a Maxon 1024, and NO gearhead. It runs great, although still way too fast.
I may just put a dropping resistor in there and let it be. The current drain is so low that a small resistor will work fine.
It's hard to beat a 1024.. that's a very long coreless and it has a backshaft so I was able to put a huge 12mm diesel flywheel on its tail. Plus, for a long time, I've wanted to see what I could do with a powerful coreless and no gearhead, just to see if they've really got the goods without one.
