This was done by mounting an aluminum disk on the shaft and braking the disk with an electromagnet. ... Wiring diagram of the d.e. motor and its control equipment. revolution, this momentary break being sufficient to operate the relay to apply current to the electromagnetic brake. A contact ... single-pole double- throw relay are in parallel with the clock, the relay locks electrically in the energized position.
|Title||:||Bulletin of the Seismological Society of America|