Was (possibly too heavy handedly) checking out an old Arnold 0-6-0 chassis yesterday afternoon and chipped a tooth off one of the axle gears. Then noticed all of them were more worn than I'd like, so wouldn't mind replacing the lot, to keep the all wheel drive.
Anyone recommend a decent source of spares, or replacement new gears?
Cheers
Your dificulty in getting gears for the Arnols is that in the UK we work in dp ("Diametrical pitch" or something like that) and on the continent they use "module" (whatever that is).
There was a company in Poland who could do the type of gears needed, but I would need to dig out the web address (somebody out there may have it easily to hand). If I can find it I'll post it.
It would also be helpful for you if you could contact Arnold (now part of Hornby international?) to find out what type (module) of gears they used so you can get replacements to match as different pitch / module gears will not easily, if at all, mesh.
The alternaitve would be to see if Brian has a dead one to use as a donor for the parts.
Although they are unlikely to have anything suitable for this particular application, Ultrascale have a good bit of information on gears and gear calculation on their web site: http://www.ultrascale.co.uk/ggs0001.php (http://www.ultrascale.co.uk/ggs0001.php)
Quote from: JulienW on March 16, 2009, 09:44
There was a company in Poland who could do the type of gears needed, but I would need to dig out the web address (somebody out there may have it easily to hand). If I can find it I'll post it.
Found It!!!
http://www.shop.kkpmo.com/
Not all the site is in English (so Babelfish may be useful) but they do take Paypal.
Found this on a technical website - helped me to understand module numbers ;):-
The module is equal to twice the distance between centers divided by the sum of the gear and pinion teeth.
M=2(r1+r2)
(n1+n2)
Where M= module no., r= gear radius (r1+r2 being distance between centres), n= no. of teeth.
For example, if the distance between centers were 12 mm, the gear had 50 teeth, and the pinion had 10 teeth, then twice the distance (2x12) divided by the sum of teeth (50+10) would be 24/60 = 0.4 = module. The module is a measure of the space between two teeth.
Enjoy :D
Thanks! That has clarified it for me. (Thinking aloud) putting it another way, you can rearrange to calculate the centres:
L = (r1 + r2)
L = M(n1 + n2)/2
or (sort of) see what sizes of gear you can get between centres:
(n1 + n2) = 2L/M
Does anyone else do "doodle" Excel spreadsheets to calculate scale sizes, speeds, wheel rpm etc or am I the only one? ;)
Cheers guys, I'll see what I can do. Looks like theres an article in this too...
I've found some possibly suitable gears in the Branchlines catalogue. Will sit down with a coffee and some algebra.
And yes, I too do doodle spreadsheets... Especially as I don't know my 25.4 times table.
Andy