[GreenKeys] Paper feed in Teletype machines

[Don Robert House]

One more time.

Friction feed - roll paper via a smooth platen held by pressure rollers.

Sprocket feed - pins on each end of and around the platen.

Tractor feed - separate tractor mechanism added to a machine that  
would otherwise be a friction feed machine.

The model 32 was only available in Friction feed.
The model 33 was available in both Friction and Sprocket, but not  
Tractor.
The model 38 was available only in sprocket feed and only with a wide  
platen.

The odd balls were the models 42 and 43...
each of these models used a special wide paper and each machine could  
use plain roll paper, as well as rolled or boxed form paper.

There were exceptions to these standards as Teletype did it's best to  
satisfy all of it's customers, however special design was expensive.

73,
Don K9TTY