Western Union "Black Box" Ticker 5-A Stock Quotation Machine

© Brooke Clarke 2007


Inside Top
Paper Tape Side
Back Side View
Fig 5 Top
Fig 1 Paper roll holder
Fig 2 Rear
Paper Handling
Polarized
                  Electromagnet
Front Right
Fig 4 Paper path
Fig 6 Polarized Electromagnet
Fig 3 stops
WU 5-A Base w/o
                  motor
SU 5-A motor w/o
                  Base
WU 5-A Motor w/o
                  Base
Base only
All the rest w/o base
Bottom of mechanism showing
single shipping screw that holds it

Background
Signaling Systems
Stock Tickers
Step-by-Step
Unison
Teletype machines
Permutation Coding
Stop/Start  Idle/Printing  On/Off  Mark/Space
Letters Figures Shift
Western Union 5-A
Permutation Coding
Bi Polar Signaling
Coil Data
Unison
Pipelined Printing
Timing
Line Connection
Type Wheel
Ticker Paper Tape 
Patents
WU 5-A 
Model 26
Loop Supply
Links

Background

Stock tickers have been around since the mid 1850s.  It was work on stock tickers that got Thomas A. Edison his start.  Prior to inventions on stock tickers he was broke.  In a few years of work on stock tickers he assigned his rights in many patents for about $40,000 ( 66 million in 2007 dollars).  This allowed Edison to setup his New Jersey labs.

Stock tickers have been developed to meet the need at the time.  But whenever there's a stock market crash the ticker system can not keep up.  So after Black Friday, Sep 24, 1869 a new generation of tickers came on line based on the Edison Universal.  Ticker machines similar to the Universal (housed in a glass dome), but faster were used through the market crash October 29, 1929 where they could not keep up.

The Western Union (they had bought out virtually all the independent telegraph and stock ticker companies by the start of the 1900s) then came out with the Ticker 5-A.  Although the 5-A prints on paper tape in a way to looks like the prior stock tickers and the paper tape was used for "ticker tape" parades, it does not use the step by step method of the prior tickers and so probably should not be called a stock ticker machine, i.e. the 5-A sounds different.  The 5-A operates at 500 characters per minute maybe 8 quotations each second.  In Fig 1 you can see that this particular one has louver vents, not drilled holes.

You could say that the Edison stock ticker was the father of the 5-A and the Model 26 teletype was the mother.  The model 26 uses a "pineapple" selector that's very similar to the one used in the 5-A although they are not interchangeable.  The 5-A uses a Unison device that's very similar to the one Edison invented and was used on most if not all the Edison stock tickers.  The 5-A runs at 500 C/M (83 W/M) compared to the 60 W/M for the 26.  Some say that the model 26 is newer than the 5-A but the first model 26 patent is dated 1926.  Note it's common with small arms to name them for the year of introduction.  I wonder if that's the case with Teletype machines with model numbers like 15, 19, 26?  The 5-A patents are for 1938.


The following is an excerpt from a Western Union news letter (I'm trying to get the source info).  It appears to have been written prior to the roll out of the 5-A.

"This new ticker which will be referred to by the name Ticker-5-A discards the step-by-step principle on which the universal and self-winding tickers are constructed.  The ticker operates on a uniform code of 8 note 1 units per character, using the start-stop principle after the manner of all Simplex printing machines.  One impulse of the code is used as a start impulse and another as a stop or rest impulse.  Five units of the code are used for the selection of the printing position on the type wheel and the sixth selection unit is used to determine whether the character to be printed is to be a letter or a figure.  The 6 selection units employ the same code as in use on the ticker automatics system and on the C.N.D. channel note 2 printer system.  The new Simplex ticker will print on a tape with the same size note 3 and shape of characters as on the present self-winding ticker.   It is a type wheel machine and the driving power and power for the various functions such as printing, shifting from letters to figures, and advancing the tape, are derived from a small motor.  The mechanism of the machine is very different from any previous Simplex printer and is adapted to operate at a high enough speed so that all of the line time possible on a single wire may be used to operate the one machine.  It is not, therefore, necessary to channel note 4 the circuit on which these new tickers will operate.

It is difficult to present an adequate picture of the magnitude of the work involved in making a conversion of  . . missing . .
will transmit _____ out to Other long distance circuits, and others will work into thicker circuit panels for which, in turn the tickers in the city will be operated.   A Drawing #34297 is included in this summary showing what the distribution circuits will be after conversion to Tickers 5-A has been completed.

The new ticker operates on one line wire and with a current of from 50 to 100 milliamperes.  It has only a single polar line note 5 magnet.  The resistance note 6 and inductance of the line magnet are considerably less than that of the self-winding ticker so that a greater number of tickers of the new type may be placed in series in one line.  It is expected that this ticker will handle satisfactorily, a day's trading of between 7,000,000 and 8,000,000 note 7shares.  If that figure is reached and surpassed, the only logical step note 8 would be to duplicate the ticker system and not attempt to design a ticker with a greater output than the one which we are about to put into service."

note 1 - The patents talk about a modification that would allow the 5-A to work with regular start-stop teletype machines, but that's not the way it was used for quotation service.  There is was used in the 5+1=6 bit isosynchronous mode. 
note 2 -What is C.N.D.?
note 3 - 3/4" wide paper tape.
note 4 - multiplex
note 5 - electromagnet or polar relay
note 6 - 20 Ohms &  150 mh
note 7 - a quotation consists of the company symbol letters and the price in numbers.  The number of shares is not on the tape.  Most stocks are sold in blocks of a hundred shares.  The average trade is probably some hundreds of shares, let's say 400.  8,000,000 shares would be 20,000 trades.  If it takes 8 characters for each trade that's 160,000 characters, at 500 char/min that's 320 minutes or 5.3 hours.  The market may have been open for 6 hours per day so that's a reasonable estimate.
note 8 - Whoever wrote this article did not allow for a completely new system, and in fact the electronic system that replaced the 5-A has a capacity that's so much higher it's hard to quantify.

Signaling Systems

Stock Tickers

Step by Step

The type wheel is stepped one character at a time very much like the second hand in a quartz clock is stepped every second.  For example if you want to print BAC the type wheel needs to be stepped from wherever it is to the B.  Then it needs to be rotated 1 position short of a full turn to print A then 2 positions to print C.  Most type wheels have about 30 characters so step by step uses about 15 bits per character (half the number of characters). 

Unison

The other problem with the step by step method is there needs to be a way to keep all the receiving printers in unison with the transmitter.  This problem plagued the step by step printers and there's a U.S. patent class devoted to Unison Devices (178/41).

T.A. Edison invented one of the first unison devices for his Universal stock ticker.  It uses a spiral groove on the printing shaft with a pin riding in the groove.  If the type wheel made about 3 turns with the pin in the groove the type wheel would lock up in a known position.  So to get all the machines in unison the sending station would send a long string of pulses thus bringing all the machines into unison.  This could be done often, whenever there was a break.  In normal operation every time a character was printed the pin was lifted out of the groove and brought back to the starting position.  Since in normal operation the type wheel is never turned more than a single turn the machine would never be perturbed by the unison device.

Teletype Machines

Permutation Coding

Teletype (the common (brand) name for a teleprinter)  machines use what's called permutation coding of the characters.  This means that unlike the stock ticker machine where you just rotate the type wheel one character for each pulse on the line the Teletype receiving machine needs to remember the order of the signals that make up one character.  Budot used a 5 level binary number system to choose one of 32 characters which is about 3 times more efficient than the step by step method.

Stop/Start  Idle/Printing  On/Off  Mark/Space

Teletype machines also use what's called asynchronous which means that the timing of each character does not need to be related to a common clock or other characters.  This is accomplished using two states of the line: key up no signal (open circuit) or key down, signal being sent (current flowing).   An advantage of On Off Keying (OOK) is that when the key is up little or no power is being used making it more economical than Bi Polar keying. 

When the line is idle a current flows that locks the selector so that it does not turn (stop condition).  As soon as the current is broken (start bit) the selector starts rotating and as it makes one turn the incoming data bits setup the character that's to be printed.  After the last data bit (5 data bits on early systems and 8 data bits on later systems) the character is printed.  The last bit of each character is always the current flowing condition which stops the selector.  The stop for mechanical printers was commonly 1.5 or 2 bits long so that you were sure that the selector stopped.  So to send a character takes 1 start bit + 5 data bits + 2 stop bits or 8 bit times per character (1 of 32). 

If a Teletype machine is powered but there is no line current (like if the line breaks) then the selector mechanism is released that the machine makes a lot of noise as it receives what's commonly called a rubout character.

For either 5 or 8 level machines during a message a large percentage of the character time is spent in the start and stop states.

Todays computers use this asynchronous method for the serial (COM) ports.  But today there's no mechanical inertia problem so only 1 stop bit is used.  A common serial description is 8N1 meaning 8 data bits, No parity and 1 stop bit.

Letters Figures Shift

The 5 level system used a Figures Letters shift in order to be able to print all 26 upper case letters and also the digits and a small number of punctuation marks (no lower case letters).  This system has a problem if a shift is not properly received, then what should have been letters is what appears to be random punctuation marks and carriage returns and line feeds in strange places or the opposite problem where what should be numbers is printed as letters.  A good operator can recognize the problem and press the needed shift key or later manually annotate the message with the correct characters, but it's added work.  The 8 level system eliminated the Letters Figures shift problems and supported the ASCII character set that includes both upper and lower case letters and a host of features.

Western Union 5-A

Much of the development work on Teletype machines was done prior to the stock market crash of 1929 so when the 5-A was designed the operation of Teletype machines was well known at Western Union since they developed them.  The 5-A includes many improvements on the Start Stop Teletype.

Permutation Coding

The 5-A uses a 6 bit permutation code.  The 5 bits are not probably the standard ITA 5 level Baudot code used with regular teleprinters and the 6th bit is used for Numbers or Letters shifting.  This way there are no separate characters (keys)  for Shift to Letters and Shift to Numbers.  So the locked in the wrong shift problem goes away.

Bi Polar Signaling

Early on in telegraph history it was discovered that on long circuits when the key was up there was likely to be false signaling because of coupling from other telegraph lines.  There are ways around this problem.  One is to keep a small current always flowing (place a rheostat across the key terminals) and that tends to lower the noise.  A much better way is to use bipolar signaling.  This can be done by using a key with a common terminal, a normally open terminal and a normally closed terminal.  With the key up a battery with it's positive terminal connected to the N.C. terminal feeds the line and when the key is down the the N.O. terminal feeds the line from the negative terminal of another battery.  Thus there is always a current flowing.  Bi polar operation was commonly done by using special relays at both the sending end and receiving end of long lines.  At the receiving end the Bi polar relay output would be the OOK signal to the Teletype machine in a local loop.

Instead of using OOK the 5-A has a built-in polarized electromagnet that responds to polarity reversals.  In Fig 6 above you can see a "U" shaped magnet marked on one end "TOP" that surrounds the  electromagnet changing it from a common type that actuates with either polarity to one where the direction of actuation depends on the polarity of the input current.

Coil Data

12 Apr 2007 - The Polar Relay has a resistance of 20 Ohms.  The nice thing about it is that when 1.1 Volts is applied in either polarity the relay actuates.  This was surprising since Teletype machines typically work with loop voltages of 80 to 160 and currents of 20 or 60 ma. 

In order to drive the Polar Relay using a PIC micro controller I think a simple 3-terminal linear voltage regulator connected as a current source of maybe 80 ma from a 5 volt supply.  An H Bridge will supply the polarity reversal and in addition give the option of either an open circuit between reversals or a short (they call it motor braking) between reversals.  Modern cameras use an H Bridge controller for focus that is both small and has the needed specs.

17 Apr 2007 - the Polar relay has an inductance of 150 mH. 
You would like the rise time to be less than 1% of the bit time so the bits have good fidelity.  A bit time is 20 ms and 1% of that is 200 uS. 
For a single time constant rise time it takes 3 to 5 time constants to get to almost 100% so the needed time constant is about 40 us.
The needed R = L / 40 us = 3750 Ohms or 3730 Ohms resistor + 20 ohms in the coil.  To get 100 ma through 3750 ohms says the loop voltage needs to be 187 to 375 volts.  But that's if using a voltage source.  The actual voltage across the coil in a steady state condition would be 375 V * 20 /3750 = 2 volts.   At the instant the loop is closed the current in the coil will be zero and will exponentially rise with the time constant  L/R, so in 200 us (5 time constants) will be very close to steady state, i.e. very close to 2 volts.  So instead of using a high voltage powers supply and a big series resistor why not just use a 5 volt power supply and a current source?  This is not the way teletype machines are normally driven so maybe there's something I'm missing.

18 Apr 2007 - On the Greenkeys mailing list I learned how to figure out the answer.  The problem occurs when the circuit is opened and the coil contains energy that needs to be dumped as fast as possible.  If a diode or Transil is placed across the coil then the time constant is long (R is low t.c. = L/R).  So you want to operate the coil in as high a voltage circuit as needed to get the desired off time.  The needed voltage is  given as:
V = L * dI /dT which in the case of an older RTTY machine running at 100 baud with 10% distortion might be V = 4 H * 60 ma / 1 ms = 240 Volts.  But for the 5-A running at 50 baud it works out to V = 150 mH * 60 ma / 2 ms = 4.5 Volts.  If a higher voltage is used the off time gets shorter.

The loop is still best implemented as a current source to keep the loop resistance as high as possible for the turn on condition.  A current source becomes a low resistance if it's saturated.  For example an analog current source set for 100 ma from a voltage source of 20 volts is trying to drive a coil that at t=0- has no current.  At t=0+ the coil current is zero and the current source can only become a short to try and supply the needed 100 ma.  Once the actual coil current gets near 100 ma then the current source starts backing off and then looks like a high impedance.  But during the critical transition time it was a low impedance that slowed down the turn on time constant to Lcoil / Rcoil, which in this case is 150 mH / 20 Ohm or 7.5 ms, way too slow.
Loop Voltage
R
100 ma
TC
ms
5*TC
200
2k
.075
0.37
100
1k
0.15
0.75
75
750
0.2
1.00
50
500
0.30
1.50
too slow
With a loop voltage of 75 and a 750 Ohm resistor the coil charging time constant will be 0.2 ms for (5 * tc) turn on time of 1 ms.
75 v * .1 amp = 7.5 watts which since this is a bi polar system is on all the time.

25 May 2007 - I've found a couple of ways of driving the selector electromagnet.
Full H-Bridge - This uses two half bridges where a half bridge consists of two electrical switches stacked one on top of the other.  The top switch is connected to the 80 volt power supply and the bottom switch to ground.  The common point of the switch is connected to one of the selector electromagnet inputs.  Another half bridge is connected to the other input.  Now when the left half bridge has the top switch on and the bottom switch off and the right bridge has the bottom switch on and the top switch off the polarity is in one direction.  When all the switches are flipped the polarity is flipped.  The forbidden condition is that you do NOT want the top and bottom switches in a half bridge both on at the same time since this would short the power supply to ground.  When N channel MOSFETs are uses as the switching elements the gate bias for the top switch needs to be higher in voltage than the source of the device, i.e, it needs to be higher than the HV power supply voltage.  IR and others make half bridge drive ICs that have a small switching power supply to do this and in addition have circuitry to prevent the shoot through that can short out the power supply.
2T2R - I made up the name for Two Transistors and Two Resistors almost full bridge.  Here the two bottom switches are MJE340 high voltage power NPN transistors but the two top switches have been replaced with power resistors one of which sets the loop current.  See RTTY the Easy Way (BARTG).  When a transistor is turned on that line wire is at ground.  When a transistor is turned off that line wire goes through the resistor to the HV power supply.  But notice that for the transistor that's turned on the resistor above it has the full power supply voltage across the resistor.  So this circuit requires a transformer (Triad N-68x) that can deliver a little more than twice the loop current.
Good information about the HV supply is on the TTY Connect Teletype Interface System web page, but unfortunately this is a Neutral or On Off Keying type of interface that's common in the U.S. the RTTY the easy Way design is from Britain where polar drive is the standard.

Unison

The 5-A does NOT use a start and stop pulse.  (the first patent below says this, but I've heard the 5-A tickers are run using the option in the second patent with start and stop pulses)  Every line polarity change is considered a clock edge.  Thus the 5-A can operate like a synchronous data protocol saving the time needed for the start and stop bits.  One of the patents calls it "self synchronous".  But the 5-A is not what's today called a synchronous system since it can stop, pause and restart at any time between characters.  Since there are no start or stop bits it's easy to combine signals using a multiplexer so that they all can be sent on one channel.

The unison device is very much like the Edison unison.  It consists of a worm gear on a shaft with a pin riding the groove.  If for example the machine is plugged in and turned on with no connection to the bi polar magnet the the pin will continue moving the the groove and after a few turns will lock up the selector.  At this point the motor is turning but the selector mechanism is quiet.  The preferred method of obtaining unison is to supply marking current polarity to the line when no characters are being sent for maybe 5 character times thus bringing the machine into unison.  Then when character bits are sent the 5A keeps in unison.

The second patent mentions that it's desirable to not stop sending thus allowing the unison device to activate, but better to keep the line active with data so that the cams stay synchronized.  How that's done without printing anything is not specified.   There are no non printing characters on the type wheel that could be used.  You wold not want to print a blank character because that would feed the paper tape.  What's needed is to have the line current reverse in such a way that the printer keeps in sync yet does not trigger printing. Maybe flipping the polarity once every word time, i.e. once every 300 ms? Not an issue since the 5-A does use the start stop method.

Pipelined Printing

The Teletype machine has the time from the last data bit plus the stop bit(s) plus the start bit to complete printing a character.  But the 5-A has no stop or start bits and so would have difficulty printing characters at a rate of 500 per minute if it all had to be done in less than a bit time.  This problem is solved by printing the character during the incoming bits of the following character.  This way there's about 5.5 (110 ms) bit times available to print the character before the next character needs to get latched.

It turns out that the 5-A knows the type wheel position after 5 bits.  The sixth bit either chooses column 1 or column 1 on the type wheel by shifting the wheel or not shifting.  The sixth bit can therefore be used as a signal to transfer the 5 bits from the input selector bars to the memory bars thus pipelining the character.  Now the input selector bars are ready to read the next input character and the type wheel has a full character time to move to the next position.

Timing

A comparable teletype machine would use the same bit time of 20 ms.  The computation goes like this:
20 ms per data or start bit and 28.4 ms for a stop bit so a character length is 20 ms + (5 * 20 ms) + 28.4 ms = 148.4 ms / character or 6.7 characters per second, which times 60 seconds in a minute is 404.3 characters per minute.  In Morse code when looking at timing the 6 letter word PARIS is used.  So to get from characters per minute to words per minute we divide 404.3 by 6 which comes out 67 WPM called 66 WPM.

For the 5-A using the same bit time of  20 ms  * 6 data bits = 120 ms / character or 8.33 characters per second times 60 is "500 Characters per Minute" and is the number often mentioned about the speed of the 5-A.  Dividing the CPM by 6 characters (letters) per word gives 83 Words per Minute.  But the 5-A is not run in the isosyncrhonous mode.

I'm not sure if my 5-A has the optional parts to make it into a start stop machine as is described in patent 2135375 or if it's an isosynchronous type like in patent 2117241.  18 Apr 2007 - It's looking more and more like this machine, and most of the 5-A machines, were configured for start stop operation and used the USTTY aka ITA2 alphabet for letters, but the figures may be unique?  There are a number of different type wheels that can be used on the 5-A.  The one called financial or business has all the fractions in 1/8 steps to do stock ticker work.  There are other versions for weather that have the circles with different patterns inside to represent different cloud types, there is also a wheel for sports reporting.

Line Connection

The cable to the line has three wires:
White - ???
Red and Black to polar coil.
The Bi Polar relay appears to be 20 Ohms resistance.  Red to Black is 20 Ohms, but none of the wires connects to the chassis.
The second patent shows a circuit (2135375 Fig 22) that describes how the output of a 6 level tape reader can be fed through some relays and a rotating selector to drive a single wire with a bi polar signal.

Type Wheel

It's very important that the type wheel print the letters at the top of the tape and the numbers at the bottom.  This is to allow quick eye scanning of a tape to separate or find a stock symbol.  Later machines tried to use two different colors of ink and print in a straight line, but the separation works the best.  Today the electronic scrolling stock ticker displays still use the offset letters and numbers for the same reason.

After the combined paper tape canister and ink roller box is removed (take out three screws) you can see the type wheel.  The type wheel is connected to the selector cage "pineapple" which determines where the type wheel will be when it's time to print a character.  The selector cage has a notch in it that takes up 2 of the 34 index positions that are possible so only 32 index positions are used and 2 are always skipped.
Type Wheel 1
Type Wheel 2
Type wheel photo 1
Type wheel photo 2

The type wheel is a smooth surfaced aluminum turning that has a rubber strip of characters attached to it's circumference.  On either side of the of seam are the characters "." in both the letters top row and the figures bottom row.  I'm guessing that the characters on either side of the seam fall into the notch on the selector drum and so are never printed.  That leaves 32 rotational positions that can be used times a letters or figures shift for a total of 64 possible characters.  They are arranged in a strange way as follows:
s
e
0
0
0
1
0
2
0
3
0
4
0
5
0
6
0
7
0
8
0
9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
2
3
2
4
2
5
2
6
2
7
2
8
2
9
3
0
3
1
s
e
a
m
3
1
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
1
9
1
8
1
7
1
6
1
5
1
4
1
3
1
2
1
1
1
0
0
9
0
8
0
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
a
m
.
S
n1
U
I
E
.
A
.
F
N
K
C
D
n2
J
R
Y
H
Q
P
Z
T
W
L
X
M
.
V
B
O
&
G
.
.

s

.
1
4

9

5

.

1

c

6

_
n
3

3

4

0

_

_
3
4

8

*

_
7
8
1
8
1
2

_
5
8

$

_
3
8

2

-

B

7
.
Notes:  I have numbered both ways so that when I'm trying to figure out the coding one of them should be correct. WRONG - Baudot was a hand entry code so is not in binary order.
n1 is a symbol that looks like a capital letter "P" with a small letter "r" underneath.
n2 is a symbol that looks like a letter "c" sitting on top of a vertical stroke "|". (cents?)
n3 is a symbol that looks like an upside-down "5". (English Pound Sterling?)

Rearranging in alphabetical order gives:

A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z

1

2

3

4

5

6

7

8

9

_
N
3

_

$

_

-
7
8

*
3
4

s
1
8
1
4
3
8
1
2
5
8
3
4
7
8
The first 5 bits of the code for a vertical pair in either table above will be the same.  This does not match any of the TTY codes where Figures 1 is paired with letter Q.    That's because it's ITA2.  This code was developed by Baudot for input using two fingers of the left hand and three fingers of the right hand and so the letters are NOT in binary order.

Ticker Paper Tape

Probably:  3/4" wide suitable for printing (not oiled like for punching).  Max outside diameter for a new spool 7".  Core center hole about 7/16".  Paper tape is available from Claus Studios he uses a band saw to cut a slice off a longer roll.

Patents


Patent 1821110
Western Union 5A Stock Ticker Top
              View
patent 1821110 Fig 1 Top


WU 5-A

1821110 (pdf) Selecting and Printing Mechanism, Sterline Morton, Howard L. Krum, Edward E. Kleinschmidt (Teletype), Sep 1 1931, 178/33R ; 101/93.19; 235/429
This patent looks like a much better fit than 2117241 & 2135375 and is much earlier.
Has two selector mechanisms, the first is set by the code and the second is set by the first.  This way a character can be printing while the next character is being decoded.

1884754 (pdf) Printing Telegraph, H.L. Krum (Teletype), Oct 25 1932, 178/28 ; 400/186; 400/257; 400/62 - stock or news broad printer - moving type wheel
has a strong similarity to the 5A stock tape printer


2117241 Telegraph Printer, R.F. Dirkes, E.R. Wheeler, V.R. Kemball  (WU), May 10, 1938 178/34 ; 178/38 (18 pages)
This is not a step-by-step printer but instead a Start-6 unit bi-polar code-Stop type printer.
Since stock quotes are almost continuous instead of actually start - stop type operation this printer can keep running and only correct the speed as needed.  Eliminating all the stop-start cycles makes operation quieter and is easier on the mechanical parts.
A type wheel is used in the 5A that similar to the type wheel used in the prior stock tickers and not a drum like in the Teletype machine.  But instead of pulsing the type wheel one step at a time it's spun by a motor until it hits a stop that selects which character gets printed.
Although this patent is for a tape printer many of the features are specified for either a tape or page printer.
178/34 = Telegraph - Printing - Page - With Type Wheel Recorder
178/38 = Telegraph - Printing - Page - With Type Wheel Recorder - with Type Wheel

2135375 Telegraph Printer, V.R. Kimball, R.F. Dirkes, E.R. Wheeler,  (WU), Nov 1, 1938, 178/34 ; 178/38; 370/305
Included in this patent are a couple of alternate cams that can be used so that this printer will properly respond to start stop type telegraph signals, although that would mean running a a slower speed.  Also that instead of letting the unison device activate by not sending anything for a few character times it's preferable to keep the line active to keep the cams turning.
178/34 = Telegraph - Printing - Page - With Type Wheel Recorder
178/38 = Telegraph - Printing - Page - With Type Wheel Recorder - with Type Wheel
370/305 = Multiplex Communications - Low Speed Asynchronous Data System (e.g., Teletypewriter Service) - Synchronizer - Start-Stop

Model 26

1595472 Telegraph Apparatus, H.L. Krum (Morkrum), August 10, 1926, 178/27
1632297 Printing Telegraphy, E.E. Klindschmidt (Morkrum), June 14, 1927, 178/17B ; 199/18
1635129 Telegraph Transmitter, C.L. Krum (Morkrum), July 5, 1927, 178/33R ; 400/478; 400/479
D112119 Printing Telegraph Apparatus Cover, G.R. Lum (Bell Telephone & Teletype), November 8, 1938, D14/472 ; D18/12
1766713 Transmitter, E.E. Klindschmidt (Teletype), June 24, 1930, 178/27
2180360 Printing Telegraph Apparatus, H.L. Krum (Teletype) , November 21, 1939, 400/141.1 ; 400/156.1; 400/164.2; 400/164.4; 400/70
2193970 Printing Telegraph Apparatus, H.L. Krum (Teletype), March 19, 1940, 400/141.1 ; 400/70
2224546 Printing Telegraph Apparatus, H. Lottermann (Teletype), December 10, 1940, 400/142 ; 400/175
2230463 Printing Telegraph Apparatus, C.A. Levin (Teletype), February 4, 1941, 178/27
2247408 Printing Telegraph Apparatus, A.H. Reiber (Teletype), July 1, 1941, 178/29
2250012 Web Guide, W.H. Eddy (Teletype), July 22, 1941, 400/615 ; 226/23

Loop Supply

Label:
TELETYPE
Input A.C. Volts: 115, Cycles: 50-60, Watts: 35
Rectifier: REC 45
Output D.C. Volts: 120/75 Amps. Cont: 0.2, Amps Int: (blank)
Supplied by
TELETYPE CORPORATION
Chicago, Illinois, U.S.A.
Manufactured by
North Electric Co., Galion, Ohio, U.S.A.
Teletype Loop Supply
This has REC 45 fitted, not the REC43 2 terminal socket.
Teletype Loop Supply schematic
Uses a strange AC 2 prong plug.

The DC output is on a 3 socket cable.

Dwg No. WG-1606-8

TM-2215 Teletypewriters TT-5/FG and TT-6/FG (Teletype Model 15 Maintenance) June 1951, 423 pages has information on the power supply and on the 255A polar relays.

Links

Teleprinters for the Radio Amateur - Creed and Company Limited. The First 50 years. -1936-9 Model 10 Tape Teleprinter sounds similar to the 5A
Creed 3X has the following in common with the 5A:
Bits, Bauds, & Modulation rates -
An annotated history of some character codes or ASCII: American Standard Code for Information Infiltration - explains the order of the 5 level code and why today it seems strange, but at the time was very logical.
Claus Studios - photos of 5-A and other quote machines

Video Links