Hamann 505


This is the only machine I have seen until now which is operated in almost the same way we use our today’s calculators.  It is the last non-printing Hamann before the end of the mechanical calculator era.

Technically it differs from it’s competitors regarding the construction of the main register.  This construction allows for a simple way of subtraction by slightly moving the carrier to the left to engage different gears.  The way division is implemented requires that the carriage registers can be halted while the main register keeps rotating. For that purpose the carriage registers are driven by a steel string which slips at certain moments during division.

Although I’m not an expert I have a slight suspicion that these machines were not very reliable. It looks like there were a lot of ad-hoc design decisions. There are also more adjustments than I have seen on any other machine.



Enter a number and hit the “+” or the “-” key.


Enter the first number and hit the “I X” key.  Enter the second number and hit the “=” key.


Enter the first number and hit the “:” key.  Enter the second number and hit the “=” key.

Function of some keys, switches etc:

Calculator InfoRepair information & pictures of internals
Hamann 505Hamann 505Hamann 505
Hamann 505

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Serial number:

Built in:


Rotation speed:


Production until:


529 933


Addition, Subtraction, Fully automatic shortened Multiplication and  Fully automatic Division

334 rot/min


1968 (Known serial numbers run from 500,001 - 531,000)

Approx. DM. 1895 in 1968/1969/1970     (Source: Büromaschinen Lexikon)