Tachometer, Electrical, 12,000 RPM, Luftwaffe Fl.20266 Drehzahlanzeiger Aerial Refueling The knob situated below the

The knob situated below the display rotates to oil reservoir 1 thru 4 (see photo of display partially rotated)

with operating limits of the last aircraft in which it was installed marked on the glass

as used in the US Navy's Patrol Bomber and Sub Chaser the Lockheed P-2 Neptune (see photo of page from the P2V7 Neptune flight manual dated 1961 depicting the instrument location on the cockpit panel with a red dot)

It has a manufacturing date of Aug 1956 stamped on its side

and clockwise in the instance of positive G's

Tachometer, Electrical, 12,000 RPM, Luftwaffe Fl.20266 Drehzahlanzeiger Aerial Refueling The knob situated below theHere is a nice specimen of a WWII era electrical Switchable Tachometer, or Drehzahlanzeiger, as used in versions of the German Luftwaffe jet aircraft Me 262, He 162, and Ar 234. This tachometer received electrical signal from a generator located proximal to the engine drive to indicate engine speed, from 1,000 12,000 RPM. According to our friends at DeutscheLuftwaffe: Since the Jumo 004 engines were only reliable up to approx. 9,000 rpm, the