ZW vs ZW (R)

[tranz4mr]

It is pretty common for ZW 275's of any kind to hum when the glue in the joint between the 2 core pieces fail. Usually this is loud.The fix is to pry the 2 pieces apart clean the mating surfaces mix up some clear epoxy, put it on as shown in the drawing, then press the parts back together with a c-clamp and let it dry. I guarentee it will not hum when your done. The last one I fixed we did it with 2 people in about an hour without unsoldering anything. We left the c-clamp overnight. Then reassembled. 

[PostwarMan07]

wow...great info everyone! I have 2 ZW's...one is quiet and one hums.  They both are 275 Watt versions.  So I could say that the one that hums is more likely to be a ZW and the quiet one is more likely to be a ZW(R)?  I don't mind the hum sound at all but just wanted to make sure everything is safe.  Thanks!

[tranz4mr]

The ZW 250 had a core made of many alternating layers placed one on top of the other with no rivets. This made the ZW250 less dense and subject to more vibration and heat. It was also more labor intensive to assemble. The ZW 275 has a 2 piece core. Each piece is layered and riveted together. The two pieces were then press fit together with some glue in the joint. Both transformers put out 180 watts to the track.

 

[Chris F]

You can click on ZW and ZW (R) here to see the differences - http://pictures.olsenstoy.com/searchcd2g.htm

Earlier ZW stacks were held together with metal "ears"; the plates could loosen and vibrate.  Later versions had riveted stacks.  I think KW's changed about the same time.

[rtraincollector]

Theres no difference there both 275 reason lionel put 250 on some was that they where waiting for a ul approval and it didn't come quick enought so they put them out with 250 to be safe but there all 275. This was in Classic Toy Trains Mag a couple of months ago.

[ADCX Rob]

1948-1949  ZW  -  250 Watts

1950-1956  ZW  -  275 Watts

1957-1966 ZW R - 275 Watts

Minor changes in the R model - slight core differences, I think there was a difference in the pilot lamp circuit and other wiring/hardware areas.

Rob 

[chuck]

Humming has to do with loose plates or a damaged frame (which are the usual cause of loose plates).

[PostwarMan07]

I was wondering what the difference is between the ZW and ZW (R) transformers.

Are the 250 watt the ZW and the 275 watt the ZW R's or did Lionel revise the 275 watt version sometime between 50 -66?

Are there noticable differences between the two?  Does one "hum" and is one more quiet?