Autopilot Speed Control Panel for A-3, A-3A, A-4, and Mark 3, 3A, 4, 644255, New Old Stock
This is a Speed Control Valve Panel for the WWII-era US Army Air Force type A-3, A-3A, and A-4 and US Navy Mark 3, 3A, and 4 automatic pilots made by Sperry and Jack & Heintz. The speed control valve is used to regulate the rate of flow of oil from the servos of the autopilot system to adjust the responsiveness of the automatic pilot when the attitude of the airplane changes.
It consists of three identical valves, marked respectively "RUDDER", "AILERON", and "ELEVATOR". The panel is usually mounted at the bottom of the gyro control mount assembly, but may be located anywhere in the cockpit, convenient to the pilot. The control knobs are turned counterclockwise for quicker response, and clockwise for slower response. The numbers on the dials indicate the degree of opening or closing.
This autopilot system was used in versions of the WWII medium bomber B-25 Mitchell (see photo from its Flight Manual, item 35), patrol bomber PBY Catalina, fighter P-61 Black Widow, and transports C-46, C-47, and C-45, as well as in multi-engine trainers and others.
It is in exceptional condition given its age, and comes in its original box. See spec sheet for dimensions.