[GreenKeys] Teletype Models

[Don Robert House]

The Model 26 is still a bit of a mystery.  As far as I can figure, it 
was built specifically for start-up manual teletypewriter exchange 
service (TWX) customers.   The Bell System was trying to grow the TWX 
network and wanted an inexpensive machine.  The internal design goes 
back to pre-model 15 using a cylinder for the type and moving the 
platen instead of the carriage.  Apparently the machine used less 
parts than a 15 and was less expensive to purchase; but when ever a 
part needed to be replaced it required a major disassembly procedure. 
The rising cost to maintain the machines caused the Bell System to 
change their minds and go back to installing M15s and M19s until the 
Model 28 was introduced.

Manual TWX service started in 1935 with the Model 14 strip printer. 
By 1939 the M15 was the favorite for TWX.  If my data is correct the 
Model 26 came into favor about 1947 and most were taken out of 
service by 1953.  Because the machine is relatively compact the 
military showed some interest but maintenance issues and paper 
handling issues killed it there also.  The only reason the 26 is 
around today is because so many were released to HAM radio operators.

Observing the machines, I have never seen a 26 that had a metal desk; 
they all seem to be wood.  They all seem to have the Bell System TWX 
data plate on the front, and they all seem to  be KSRs.  Since I have 
no manufacturing data on the M26 and only primitive manuals,  I am 
not going to hazard a guess on how many exist today.

We have a 70 volume library of Bell System Practices and the model 26 
has no apprearance in any of them.  There is no layer for the 26 
either.  571 is for special customers;  572 is for 14, 15, 19, 20; 
573 is for the 28;  574 is for 33, 35, 37.  There were no 29s or 32s 
used by the Bell System unless you catagorize a LARP as a 29. The 
LARP4 we have is a 6 level punch with the feed hole being optional as 
to its position.  I consider it to be a prelude to the BRPE.  The 
BRPE is probably the most flexable punch Teletype made as it could be 
5 level only, 6 level with advanced feed hole, or adjustable for 5, 
6, 7, or 8 level tape.

I believe that the model numbers are sequential. But there are some 
interesting gaps that make one wonder what was in between:

10, 11, 12, 14, 15, 19, 20, 26, 28, 29, 31, 32, 33, 35, 37, 38, 40, 
42, 43, 44, 45, 47, 53
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Don Robert House
North American Data Communications Museum
URL: http://www.nadcomm.org
Computer Museum of America
URL: http://www.computer-museum.org