Does OO = HO??

[CNWman]

Bingo!

Part of the confusion, which appears to reappear, is that there were TWO different "OO" scales. The American OO was 1:76 scale with 1:76 scale track. British OO is 1:76 scale with 1:87 scale track, done so small British prototypes could fit the available electric motors. HO was originally British, half of British 1:43.5 O scale (1.25" real-world equals 4'8.5" in British O scale.) American O scale is traditionally 1:48, and runs on 1:43.5 scale track (1.25" real-world equals 5' in American O scale.)

In case your head doesn't hurt enough, there is a fine-scale British OO that runs on 16.5mm track (4'8.5" at 1:76) and a fine-scale American O (Proto:48) that runs on track that runs on two-rail track approx. 1.17" (4'8.5" in 1/48 scale.)

I'm not even going to touch narrow gauge...

I've bolded & underlined the sources that caused my confusion. Thanks for explaining it out jetrock!:thumb: bounce7

 

[60103]

CNWman: yes, in the late 30s, Lionel made a start on OO gauge. I finally, actually saw some a couple of years ago, in a museum.
Lionel went at it in a big way. You could get fine and coarse scale and 2- and 3-rail track. This meant the one locomotive (I think they just had the NYC Hudson) had to be stocked in 4 variants. Lionel OO was one of the war casualties.

For fun, American O gauge came in 3 flavours at one point: 1:48 on 1 1/4" track, 1:48 on 1 3/16" track; and 17/64" to 1' on 1 1/4" track. The second variant was called Q gauge.

 

[CNWman]

well not really

Lionel OO was one of the war casualties

Not really. Lionel stoped OO because of some production problem or that the big cheses thought is wasn't profitable. Fun Fact: there are only 27 pecies, track and all, in a full OO colection

 

[toptrain1]

Scale - Gauge relationship : The term HO was to have meant half O gauge. OO was to be Half O. What now is HO gauge is scale is 3.5mm to the foot, and a ratio of 1/87.1 . The track gauge is 16.5mm or 0.648".
OO is a scale of 4mm to a foot, and a ratio of 1/76. The track gague for it now is the same as HO at 16.5mm. OO,s original track gauge was 19mm or 3/4". This is the correct scale track guage for OO. Now in modern times OO and HO tho built at different scales run on the same gauge track 16.5mm. This makes OO top heavy in appearence and opperation.
When you compare a old Lionel OO gague Hudson to a Gilbert HO Hudson scale wise they are the same in size. The lionel runs on 19mm gauge track and the Gilbert runs on 16.5mm track. Again if you compaire a Lionel Hudson to a Riverossi Hudson the scale size of the Lionel is larger. The track gauge is also larger for the Lionel OO.

 

[Triplex]

In case your head doesn't hurt enough, there is a fine-scale British OO that runs on 16.5mm track (4'8.5" at 1:76) and a fine-scale American O (Proto:48) that runs on track that runs on two-rail track approx. 1.17" (4'8.5" in 1/48 scale.)

Actually, I've never heard correctly-gauged 4mm scale called OO in Britain. If it's 18mm gauge, it's EM. If it's the exactly correct gauge (18.8-something mm), it's P4 (Proto-4).