Suction Gage, AN 5771-5, US Army Air Force WWII
This is a WWII-era Suction Gage, AN 5771-5, made by Collens. This indicator has a serial number prefix "AF-43", evidence of a manufacturing year 1943. The AN 5771-5 Suction Gage was used across all aircraft of the US Army Air Corps, including bombers B-17, B-24, B-25, fighters P-38, P-40, P-47, P-51, and transport C-47.
The Suction Gage measured the amount of vacuum generated to power the pneumatically-operated gyroscopic instruments, such as the Gyro Horizon (Flight Indicator), the Directional Gyro, and the Turn and Bank Indicator, as well as automatic pilot systems. The vacuum is generated by either a engine-powered vacuum pump or externally-mounted power venturi tube. A loss of suction could render these instruments inoperable or unreliable.
This indicator is experienced but in good condition for a 70yr+ old artifact. The face paint is curled a bit, see photos. Measures approx 2 inches diameter and 2 inches deep.