I think somewhere in the past that I read that the core and coil in the 250W and 275W ZW is the same, that after introducing the 250W Lionel submitted the same design to UL for a 275W rating and got it. Am I imagining things or is it a fact?
Jim
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The coils are not the same, and have different part numbers. The newer laminations are also riveted, which required a redesign of the coil support brackets. There were other changes in the design of the transformer also, including redesigned whistle control assemblies and new circuit breakers.
The changes are documented in the service manual pages for the transformers.
Larry
It's not that concrete, even from the service manuals, when the changes were made. All 250 models were essentially the same, but early 275 models shared more in common with the 250 by far than the final "R" revisions:
The Type R is clearly datable to 1961 by the service manual pages (the date is on some reproductions, though not Greenberg's) and the instruction sheet ZW-251 (dated 1-61). The riveted laminations came long before that, but not all ZWs with riveted laminations are Type Rs; those had further changes, and the use of 18V pilot lights and short circuit lights indicate the Type R (according to the Service Manual).
There are more differences among the several different 275 watt(input) ZW versions that folks quibble over in trying to get the "best" one, when in fact there is very little performance difference if any at all in all versions of the ZW from 1948-1966... the 250 and early 275 does run warmer.
Check this out: Tranz4mr’s ZW Page
Electrically they are the same. besides a few parts changes the only thing that really changed was the way Lionel calculated the wattage. I think? Some one needs to confirm this.
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