These alternators are powered by compressed air.
They were designed for applications that had compressed air available but no electricity,. An alternator was needed to maintain battery charge for sensor and communication systems.
The assembly bolted into an enclosure. The battery was located inside the enclosure.
The unit with the air motor was activated by an external solenoid valve that opened when the battery voltage dropped below a set point. The regulator was designed to maintain a 12V SLA battery.
The other used an internal air turbine.
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