Source : Webster's Revised Unabridged Dictionary (1913)

Tachograph \Tach"o*graph\, n. [Gr. ? speed + -graph.]
   A recording or registering tachometer; also, its autographic
   record.

Source : WordNet®

tachograph
     n : a tachometer that produces a graphical record of its
         readings; used to record the speed and duration of trips
         in a motor vehicle