The electric motor could have more than one armature on the shaft, and these could be electrically coupled in series for slow speed and in parallel for high speed. (These alternative connections were known as "group down" and "group up", respectively.)
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Yes, this was the submarine's first trip.
A submarine is to spy on ship movements and if necessary sink ships
Usually by inflating bags that have been placed inside the submarine.
Russian submarine Delfin ended in 1917.
the oldest submarine was made in 1620. Added: Currently as of May 2010, the oldest working submarine in the US Navy is the USS Philadelphia SSN 690. The keel was laid down in August of 1972, and was commissioned June 25, 1977. She is a Los Angeles Nuclear Attack Submarine. In a formal ceremony in her homeport at the Groton Naval Base on June 25, 2010 the USS Philadelphia SSN 690 will be decommissioned after serving 33 years. **Finish Strong**