WWII German Luftwaffe Fl.20286 elektr.Drehzahlanzeiger (später Einheitsdrehzahlanzeiger), 1944 - 16b71 - - RARE Fl.20286 elektr.Drehzahlanzeiger (später Einheitsdrehzahlanzeiger), 1944. Designation: electr. tachometer Requirement Character: Fl. 20286 Dev
RARE Fl.20286 elektr.Drehzahlanzeiger (später Einheitsdrehzahlanzeiger), 1944.
Designation: electr. tachometer
Requirement Character: Fl. 20286
Device No.: 127-1301 C-2
Type: EW 16
Measuring range: 400 – 3600 rpm
Manufacturer: hnf (Deuta-Werke, Berlin)
Year of construction: approx. 1944
Since the distance from the engine to the instrument panel is too great for direct mechanical transmission, a remote speed measuring system was installed here.
The system consists of a speed sensor driven by the engine and one (or more) display instrument(s). The tachometer and tachometer are connected by an electrical cable.
The tachometer, a small alternator, is driven by the engine via a short connecting shaft. The magnitude of the voltage generated depends on the drive speed of the motor. The display device of the electrical remote speed measuring system is basically a voltmeter calibrated in rpm. Both electrodynamic and permanent-magnetic voltmeters are used. In the case of the latter, the AC voltage generated must be rectified, since they only display DC voltage.
The permanent-magnetic tachometer contains a fixed permanent magnet; a moving coil is mounted in its magnetic field. The pointer of the instrument is connected to this moving coil. The voltage generated by the encoder (generator) creates an electromagnetic field around the moving coil, causing the coil to rotate against a spring force, the size of which corresponds to the applied voltage.
The electrodynamic display device has the advantage over the permanent-magnetic one that it can work with alternating current (without a rectifier). It is much lighter and does not deflect the magnetic compass. On the other hand, the lower measurement accuracy is the opposite.