Ever seen or used one ?

Holy cow! That thing is pretty valuable. As to what it does? Right.....

tach·o·graph
ˈtakəˌɡraf/
noun
noun: tachograph; plural noun: tachographs

1. a tachometer providing a record of engine speed over a period, especially in a commercial road vehicle.

 

Had one in the trucks I drove in 1972 and 3

 

My 89 IHC has one. Florida Rock & Tank was still running them in the late 80's. Like others said and turn your disc in with your paper work every day.
That thing on the right is a key so liar's can be locked out, no rubber bands and stuff that way. Just time and MPH on theirs as I remember.

 

I remember seeing them. Never had the pleasure of having one in the truck

 

Just saw one that worked on a flea market table at an ATHS truck show for $50. Was going to send it to the FMCSA and suggest they place it in a sensitive area of the body.

 

We had them when I hauled fuel in the early 90s.

Also very similar to Martin-Decker pressure recorders I used in the 80s in oilfield cementing and stimulating... which could be similarly "corrected."

 

Yes I seen one before and have used one too . Good old fashioned tattle tail

 

70's try 50's,
Had in in a new 1975, used one in 1984 while hauling gas.