odd photo

[NW Mailing List]

ok, the Z1b's had 1 piece cylinder castings vs the slide valve versions.

I'm staring down some pictures of the Z1a's in Princes book,  Like my 
model of the Z1a, the rear and front cylinders the size differrence is 
not really that much, if you stared at it from the side, they look about 
the same size. I can see the diameter differences, thats obvious, but 
the size differences is not bizarre.

Alco made the first Z1's, then Baldwin the next set of the Z1a's, then 
Schnectedy the 3rd set, all Z1a's.

1319 the front cylinder looks roughly half the bulk diameter of the drivers.
1368 the cylinder looks almost the diameter of the driving wheels.
(I'm talking the outward appearance, not that the actual cylinders might 
still be 35 inches)
1368 has the slide valves as does the 1319.
some of these front cylinders are looking like monsters like they came 
right off a Y6b.
Someone or you mentioned some of the Z1b's were refitted with slide 
valves for some reason and downgraded to a Z1a? One Z1b pic shows a 
smaller front cylinder similar to the Z1a but using the piston valve. 
There seem to be some wide variations in applications how the Z1a-Z1b 
mods happen and parts used. The Prince book does not mention this 
discrepancy, nor do I see mention of a reconvert Z1b to a slide valve, 
not that they couldn't have, but you know the N&W, heavy experimenter.

I know now if I wanted to convert my model Z1a to a Z1b maybe I'll 
borrow a Y6b front cylinder casting.

I may have to stare down the N&W NRHS archive on this. They show some 
little things like boiler patch repairs on the M2c's

-Lynn-


On 5/19/2015 10:42 AM, nw-mailing-list-request at nwhs.org wrote:
> Subject:
> Re: odd photo
> From:
> NW Mailing List <nw-mailing-list at nwhs.org>
> Date:
> 5/19/2015 7:17 AM
>
> To:
> "NW Mailing List" <nw-mailing-list at nwhs.org>
>
>
> Lynn -
> All the low-pressure cylinders of the Z-1s and Z-1as and Z-1bs were 
> the same size – 35 inches.  The difference is in the valves.  The 
> slide valves were the flat-top assembly on the top of the cylinders; 
> the slide valve assemblies could be separated and removed from the 
> cylinders.  The rounded tops denoted piston valves; these 
> cylinder/valve assemblies were cast in one piece.   One of the Z-1as 
> sold to the Tennessee Central (1396) had piston valves; one of the 
> Z-1as sold to the Interstate (the former 1422, I believe) also had 
> piston valves.
> Where did you get the idea that any of the Z’s had cast frame/cylinder 
> assemblies?  None of the Z’s were so equipped; they all had built-up 
> bar frames with separate cylinders.  The only N&W engines equipped 
> with one-piece frame/cylinders were the As, Js, S-1s, S-1as, rebuilt 
> Y-5s, Y-6s, Y-6as and Y-6bs – 202 locomotives.
> Lynn – you need to not out-think this thing.  None of the Z’s had 
> cylinders that were any more huge than the others.  They ALL got their 
> boiler pressure raised to 225.  They were excellent engines.  But none 
> got cast frames or roller bearings.
> EdKing

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