Tachometer, Chronometric, Type C-9A, WWII Ki-100 Here is vacuum-driven Gyro Horizon

Here is vacuum-driven Gyro Horizon Indicator Type AN-5736-1

the Contactor is ready to go

and the gauge measured each engine's crankshaft torque by measuring oil pressure in the engine planetary gear drive system

and its serial number prefix is AC-42

Tachometer, Chronometric, Type C-9A, WWII Ki-100 Here is vacuum-driven Gyro HorizonHere is an exceptional example of the WWII era Chronometric (i. e. mechanical) Tachometer, Type C 9A, as used by single engine aircraft of the Air Corps US Army. According to the US Army Air Force Maintenance Interchangeability Chart dated Feb 1945, the C 9A tachometer was used in fighters P 40 Warhawk (E N), early versions of the P 47 Thunderbolt, and P 51 Mustang, dive bombers A 35 Vengeance and A 36 Apache, and transports UC 61 and UC 64A. This