ndbprr wrote:Am I missing something? I thought Stewart did the C636 or was that the C630 after the C628?
Thanks for that!
I had forgotten the Stewart, now Bowser C630. It seems reasonably priced, but there are still the basic differences from a 630 to 636 to be overcome.
I think I'll buy a 630 anyway, they look good and are very similar to the 636.
Modifying the truck frames would be relatively easy, but changing the intercooler hump would be relatively difficult. You could always ignore that difference and having changed the truck frames, paint it for BN or SP&S.
M636C
sfrailfan wrote:I have read convos online saying since only about 70 or so C 636s were produced it would probably be a risk for say Atlas to model them. Not even Tiger models has one listed on their site. So what would be the most important things for me to change/modify assuming this is possible. (I have yet to look closely enough to make this comparison) I thought the Alco speciallists and experienced kitbashers might have something to let me in on. I know the hi-ad trucks will be a challenge, (if not impossible)
There were some brass C636 models made in HO (I assume you are talking about HO) but there probably weren't many of those made either, like the prototypes.
So kitbashing is the way to go. You don't say which road you are modelling. Some changes were made, particularly to the intercooler radiators at the front end of the engine, and these varied from road to road.
But starting with plastic models, you basically have the Mehanotechnika C628 to start with among models still being sold. There were C630 models made by Tyco, which were unfortunately high hood versions, which had two types of chassis. The earlier models had quite reasonable trucks, but the later units had ghastly trucks (both in appearance and performance). Tyco also made a C430, and combining the cab from the 430 with the long hood from the 630 gives you a reasonable C630 body.
There are differences between the C630 and C636 bodies - the 630 had two grilles (one above the other) on the intercooler hump while the 636 had only one, and the 630 had slightly smaller radiators. The four C&O C630s had Alco Hi-Ad trucks, and looked very similar to C636s. These units were converted to 3600HP and were shipped to Australia where they were used by Robe River Mining in Western Australia.
Do you have C636 drawings? There were a good set in RMC some years ago, and these might still be available in a back issue. The issue should be able to be found on this website's index.
If you want to use the C628, it would be best to replace the cab, because while the 628 had a straight "V" cab, the 636 had a "square" cab door and driver's window giving a sort of "W" shape to the cab front. I think Mehanotechnika also make a C430, and this might be a source of a cab moulding. The changes required to a 628 hood would be the addition of the intercooler assembly, and the box forward of the radiator covering the radiator header tank. These are both basically just rectangular boxes that could be made from styrene sheet. The radiator grille and shutters on the side of the intercooler box might be cut down from EMD corrugated radiator grilles from an SD40-2 or similar.
The Australian C636 was basically the same as the US version and one ex BN/SP&S C636 ran in Australia, also with Robe River in Western Australia.
Incidentally, the M636 frames were an entirely different design and were slightly longer than the C628/630/636 which all shared the same frame.
The Hi Ad trucks are much easier than they look. The truck frames themselves are basically similar to the GE "Floating Bolster" design, and I'd start with that type. The difference in appearance is due to the overhanging bolster, the traction rod and the big external coil springs supporting the bolster. If you regard these as a separate add on and make them up as a single unit to add to the existing truck frame, it isn't that difficult. Remember that the traction rods face opposite directions on front and rear trucks.
So given that the GE truck is a good basis, I'd recommend using an Athearn U33C or U36C Blue Box kit chassis, although other GE six axle chassis are available now and the choice is up to you. The Tyco body should fit reasonably easily but the Mehano C628 body might need some modification.
By the way, I used to work with the Australian C636 locomotives and my forum name is the model code of Mt Newman M636 units which were fitted with Alco Hi Ad trucks rather than Montreal Dofasco trucks (just as CN 630Ms were the reverse!)