a lot of the older engines had an external gear that contacted with the rubber tyres. maybe this pressure helped them grip better?
my photo shows just such a gear. it has one on both sides, and when sitting on the wheels, its all pressed together. this is an old merry-go train. if i recall, the tracks are grooved the same as the modern ones, but its been a while since i looked.
![[Image: merrygotrain%20011edit%20Small.jpg]](http://i1209.photobucket.com/albums/cc399/sunhuntin/merrygotrain%20011edit%20Small.jpg)
my photo shows just such a gear. it has one on both sides, and when sitting on the wheels, its all pressed together. this is an old merry-go train. if i recall, the tracks are grooved the same as the modern ones, but its been a while since i looked.
![[Image: merrygotrain%20011edit%20Small.jpg]](http://s1209.photobucket.com/user/sunhuntin/media/merrygotrain%20011edit%20Small.jpg.html)
my website address has changed: https://sunscollections.weebly.com/
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