Autopilot, Directional Gyro, Type A-3A, Jack & Heintz

Here is a WWII-era Directional Gyro module of the Type A-3A Automatic Pilot system, made by Jack & Heintz, with a serial # prefix of 42, indicating a manufacturing date of 1942, for the US Army Air Force.  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.

The A-3A autopilot system was pneumatically-operated, hence the suction gauge in the upper right corner of the Vertical Gyro to indicate the performance status of the pneumatic system.  

Measures approximately 5 inches by 8 inches and 12 inches deep.