Type name / number: 8100 Sundstrand's Underwood Adding machine (hand driven)
Production / SN: 266540
Calculating principle: Rocking Segment
Calculating functions: Add, Subtract with nine complements
Input accuracy 8 digits
Calculating accuracy: 8 digits
Designer: The Sundstrand brothers
Production year: 1940
Case material: Aluminium
Weight: Kg
External links:  
Previous owner: Marktplaats, Rick, Apeldoorn, the Netherlands
Cosmetic imperfections:
(I accuse no one):
The case is broken on two locations, lost paint and is rusty. Some screws are missing
Date of receiving: 2015-06-12 Picked up at the owners house. The machine was used by his father.
Machine story: 2015-06-13
The machine was blocked and internally full of dust at arrival. Cleaned the machine and sprayed with penetration oil. The keyboard which turned out to be an different mechanism than I had seen sofar. The pin box is fixed and the pushing and scanning mechanism turns in front and shift behind the pin box. Not well documented at other web sites.
The handle was halted by a little knock in the right side plate, for wrong movements of mechanisms. I firs tried to reset the key board which was successful after trying the lock mechanism to move turn etc.
The handle turned to its full extend and let him loose to get the maximum force for the back turn. After several tries it worked. The keyboard was free. Adding was sort off working but far from OK. The scanning mechanism is not going back to zero after entrance of a number.
Total sum was blocking the machine again and again.
I made same pictures of the for me new key board mechanism and put it at the how are the calculate at the Rocking segment chapter.

will be continued


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