Original-Odhner 239MECHANICAL CALCULATOR · INTERACTIVE RECONSTRUCTION
ACCUMULATOR 13 WHEELS · RESULT 0000000000000
SETTING 10 DIGITS 0000000000
COUNTER 8 DIGITS 00000000
SETTING LEVERS0000000000
CARRIAGE1 / 8
SETTING0000000000REVOLUTIONS00000000RESULT0000000000000
Move a setting lever to enter a number.

Operating the Model 239

This is one fixed, front-facing 2D reconstruction of the cream Original-Odhner 239 in the supplied photograph. The mechanical arithmetic engine is retained from the earlier prototype. It is an interactive illustration, not a photograph overlay.

Set and calculate

Drag each of the ten numbered setting levers vertically, from 0 to 9. The ten-digit checking window above the levers follows your setting. Use the main crank on the right: tap the ↻ direction beside it, or tap the crank grip, to add one revolution. Use ↺ to subtract. A crank revolution updates the 13-wheel accumulator and 8-wheel revolution counter.

Move the carriage

Press either of the two black square shift keys at the front to move one decimal place. Alternatively press the small silver front release and drag the carriage rail horizontally. Eight detents provide seven single-column intervals. Both lower registers and their two clearing handles travel with the carriage; the lower apron stays fixed.

Clear and transfer

The black lever beside the main crank quick-clears the ten-digit setting rotor. Turn the small left carriage crank to clear the revolution counter; the small right crank clears the accumulator. To back-transfer an accumulator value: quick-clear the setting, pull the small black transfer key near the result window, then turn the right clearing crank. Only values fitting the ten-digit setting register can transfer.

Example · 123 × 45

Set 123 using the three rightmost levers. Shift carriage to position 2 and turn the main crank four times clockwise. Return to position 1 and turn five more times. The counter reads 45, the accumulator 5535.