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wm3798
USA
4219 Posts |
 Posted - 11/19/2009 : 10:24:09
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In the old A/K RSD's, the third axle is geared by a chain of three tiny gears. These are pretty fragile, and the couple that I've worked on had problems with the little gears losing teeth, and therefore binding up the whole works.
The good news is that Atlas still offers these as spare parts, but I have to imagine they're getting scarce due to the age of the design and being out of production for 20 some years...
I find that the newer model operates plenty smoothly, and probably more reliably than the old one, especially due to improved pick ups.
Lee |
Mill Street Studios - Custom N Scale Offerings.
www.wmrywesternlines.net |
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brokemoto
USA
2662 Posts |
Posted - 11/19/2009 : 10:39:22
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You are correct, there LW, the newer Atlas RSD-4 does run much better and much more reliably than does the old A/K version.
It does not, however, pull as well as the older version. The funny thing about this is that singly, it will pull only six loaded MT gondolas and an MT caboose up a one per cent grade at twenty five SMPH. Seven at that speed will send it into full slip. Two of them, however will pull eighteen loaded MT gondolas and an MT caboose up the same incline at the same speed. I can get the Kato RSC-2 to pull ten loaded MT gondolas and an MT caboose up the same hill at the same speed. Eleven will make it slip, but it will get up the hill. It will get twelve up the same hill with a running start, at unprototypical speeds, and a large amount of slipping. Thirteen will make it slip totally.
Thank you for your consideration and support. |
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PGE_Modeller
Canada
137 Posts |
Posted - 11/20/2009 : 19:50:14
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quote:
Originally posted by Spookshow
The Century trucks use two idler gears to turn the "far" axle and one to turn the "near" axle. The RSD trucks are noticeably shorter, so I guess there isn't room for that extra "far" gear.
Cheers,
-Mark
It's interesting that the RSD-4/5 truck on the model is shorter than that of the Century 628/630 as the drawings in "LOCO 1, The Diesel", Model Craftsman Publishing Corp. (Carstens), 1966, show that the wheelbase of the trucks on all those locomotives was the same - outer axles 5'-7" c-c, inner axles 6'-11" c-c. At a quick measurement, I get the model Century 630 truck at 5'-8"/6'-10" and the old A/K RSD truck at 5'-4"/6'-5". I don't have a new RSD truck on hand to compare.
For comparison, the RSC-2 truck was 5'-3"/5'-3", the RSC-3 truck was 5'-6"/5'-6" and the Dofasco (Canadian) C-630M, M-630, M-636 truck was 5'-7"/5'-7".
Cheers, |
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Edited by - PGE_Modeller on 11/20/2009 19:51:24 |
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atsf_arizona
1665 Posts |
Posted - 11/20/2009 : 23:01:56
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PGE_Modeller,
Thx for the info... that was the type of info that I was wondering about....
I'd thought the prototype Atlas C628 and C630 trucks should be the same size as the
RSD4/5 trucks, hence the model trucks should be same/similar as well.
I suppose someone has already proven that you can't use the Atlas C628/C630 trucks on
the Atlas RSD4/5 mechanism? Or can you? |
John Sing
San Mateo, Calif
http://home.comcast.net/~j.sing
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Modeling the Santa Fe's Peavine Line (Ash Fork->Phoenix, Arizona) in the 50s and 60s |
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Spookshow
USA
5077 Posts |
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