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ORIGINAL  -  ODHNER     MODEL  27


TECHNICAL DATA  of the  Mechanical  Calculator   O D H N E R   » Model 27 «
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Serial Number:       27-174940

Dimensions:   (ca.)  Width   =     12 "  /  30 cm
                     Depth   =      6 "  /  15 cm
                     Height  =  4_1/2 "  /  12 cm

Weight:       (ca.)  11_2/3 lbs  /  5.3 kg

Mechanics:           Pin-Wheel / Sprossenrad
                     10s Carry Mechanism
                     Counter Stepping Mechanism Animation

Functions:           Add, Subtract, Multiply, Divide
                     Back-Transfer / Rueckuebertragung

Registers:           Input       =  10 Decimals
                     Counter     =   8 Decimals
                                       (NO Carry; Neg.Figures RED)
                     Arithmetic  =  13 Decimals
Manufacturer:
                     ORIGINAL-ODHNER 
                     Goeteborg / Sweden
                     1935

H O W   T O   U S E   the  ODHNER  Model 27
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BASIC SETTINGS:
===============

(a) Crank:
----------
For addition (+) the crank is turned clockwise; for subtraction (-) the
crank is turned counter-clockwise. In idle position the crank is down &
locked. To make one or more turns with the crank, pull out the handle
to unlock. When finished the turn(s), let the handle snap into the lock
again. The locked down position only makes other functions accessible.

REMARK:      Every started turn has to be finished completely!
             Accidentally started turns are correctible somehow.

(b) Clearing Registers:
-----------------------
Procedure to clear the input:
    Pressing the BUTTON on the right side (with the thumb) will close
    the lower ends of the "input-slots". Turn the crank clockwise until
    all input-levers are reset because of this new barrier in the "input-
    slots". Than turn the crank COUNTER-CLOCKWISE (!) until the BUTTON
    POPS BACK and re-opens the barrier of the "input-slots".

The counter unit
    will be cleared with the CRANK on the LEFT SIDE of the carriage

The arithmetic register
    will be cleared with the CRANK on the RIGHT SIDE of the carriage

(c) Shifting the Carriage:
--------------------------
Pressing down the LEFT or RIGHT BUTTON IN FRONT will move the carriage
one step left or one step right. When the SILVER KEY is pressed, the
carriage can be moved continuously right or left by hand.

The left position "1" is the "Start Position" of the carriage.

(d) Back Transfer:
------------------
For continuous multiplication the contents of the arithmetic unit
can be back transfered into the input register with this procedure:

  o  Clear input register as described above.
  o  Pull the BLACK KEY right on the arithmetic unit.
  o  Make a "CLEAR" (clockwise) turn for the arithmetic unit.
     This clears the arithmetic unit ...
     and set the input levers to the transfer-value.

The BACK-TRANSFER-Procedure works in position 1 of the carriage only..
If the  BACK-TRANSFER-Lever  is set accidentally, push the little 
button under it to release the BACK-TRANSFER-Lever.

ADDITION & SUBTRACTION:
=======================
Example:     123 + 45 - 6  =  162

Clear input, counter and arithmetic units.

ADD: Enter the first number (123) in the far right of the input unit.
Make a positive (clockwise) turn with the crank to transfer the number
into arithmetic unit. The counting unit displays the figure 1. Enter the
second number (45). Make a positive (clockwise) turn with the crank to
add the number. The arithmetic unit displays the intermediate sum (168)
and the counting unit displays the figure 2.

SUBTRACT: Enter the third number (6). Make a negative (counter-clockwise)
turn with the crank. The arithmetic unit displays the result (162) and
the counting unit is decreased by 1.

REMARK:      NEGATIVE RESULTS are displayed in the arithmetic unit
             as the COMPLEMENT of the next higher 10, 100, 1000, ...

             Example:   -12  =  99...9988

MULTIPLICATION:
===============
Example:     123 x 45  =  5535

Clear input, counter and arithmetic units.

Enter the multiplicand (123) in the far right of the input unit. The
multiplicator (45) has two digits, so the carriage is shifted to
position 2. Make positive (clockwise) turns with the crank, until the
first figure of the multiplicator (4) will appear in the 2nd position of
the counter unit. Shift the carriage to position 1. Repeat making positive
turns with the crank, until the second figure of the multiplicator (5)
appears in the 1st position of the counter unit. The multiplication is
done: The multiplicand (123) stays in the input unit, the multiplicator
(45) in the counter and the result (5535) is in the arithmetic unit.

DIVISION:
=========
Example:     22 : 7  =  3.1428571  Remainder 3

Division requires 3 steps:

(1st) To Set the Dividend into Arithmetic Unit:
-----------------------------------------------
    For the maximum number of decimals, pull out the carriage to the far
    right position. Enter the dividend (22) in the far right of the input
    unit. Make a positive (clockwise) turn with the crank to transfer
    into arithmetic unit.

(2nd) To Set the Divisor into Input Unit:
-----------------------------------------
    Clear the counter.
    Enter the divisor (7) above the dividend (22).

(3rd) To Divide:
----------------
    Make negative (counter-clockwise) turns with the crank until the
    arithmetic unit shows an "underflow". Make one positive (clockwise)
    turn with the crank. Move the carriage to the next left position.
    Repeat this procedure until the required number of decimals ...

    The result (3.1428571) is in the counter unit ( in RED ), and the
    remainder (3) is in the arithmetic unit. The divisor (7) stays in the
    input unit, therefore an additional decimal can be estimated ...
    ( 4, cause 4 x 7 = 28).

impressum:
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© C.HAMANN        http://public.beuth-hochschule.de/~hamann        08/07/09