dynagraph

\\ˈdīnəˌgraf, -rȧf\ noun (-s)

Etymology: Greek dynamis power + English -graph

: an apparatus in a railroad car for recording the condition of a line of track, the resistance of a train, its speed, and other features of its performance

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dynagraph

(ˈdaɪnəgrɑːf, -æ-, dɪn-)

[f. Gr. δύνα(µις power + -γραϕος writer, -graph.]

The name given in the United States to a machine of the same character as the dynamometer car on some English Railways, used for mechanically reporting the condition of a railway line, the speed of a train, and the power used in traversing a given distance.

These elements are recorded on a paper ribbon moved by means of gearing from one of the axles of the car or van which carries the machine.

in Century Dict.