Other Patents
Bull continued working on improvements for the machine and also in developing new machines. For example, a sorting machine and a new tabulating machine.
Some of the notable improvements are: the change of switches that controlled the entry of punched cards and the expansion device in larger scale.
The reading device was the most critical part of the machine. Built with conductors of electricity or springs, punched cards were introduced, the springs passed through the holes producing contact. The springs only passed through the holes of the punched cards, and then the information got stored. He obtained the ideas for this machine by stealing the notes of Henrik Hartzner, his Danish partner. One of the main problems of this method was the low durability of the material of the cards, which meant that the method did not always work the right way. Another major problem was the dust that entered the holes of the contacts. Finally, one of the biggest problems Bull and Knutsen had to face was that because of the contacts, sparks were created and made the machine to crash frequently. All these details were being constantly improved.
Production of Bull machines was rather slow. In 1921 there was a production of 2 machines, 2 in 1922, 2 in 1923, 4 to 1924 and 6 in 1925, distributed among companies in Norway, Denmark (Hafnia as a remarkable client), Finland and Switzerland. There were problems constantly and because of that, Knut Andreas Knutsen was constantly traveling to these countries, repairing and modifying equipment for the clients.
Read more about this topic: Fredrik Rosing Bull