Autopilot, Directional Gyro, Type A-3A, Jack & Heintz.
I was told when I bought this item it was flown on an aircraft that was used in the Berlin Airlift. I have no proof of that other than that this item was built in July 1942.
Some corrosion but otherwise nice piece of aviation history.
Would be connected with the Vertical Gyro module and the Speed Control Valves of the same system and installed on the flight control panel. The A-3A autopilot was used in bombers B-24C Liberator, B-25C,D,G Mitchell (see images from B-25 flight manual), fighter P-61 Black Widow, and transports C-46 Commando, C-47 Skytrain, and C-54 Skymaster.
The pilot would set the desired heading, indicated by the bottom compass card, by turning the center knob. As the aircraft turned to the selected course, the top compass card would rotate to match the heading on the bottom card. The Rudder Trim knob is used to adjust the course if it is off by no more than 3 degrees as compared to the aircraft’s direct reading magnetic compass.