slidometer

from The Century Dictionary.

• noun An instrument used to indicate the strains to which railway-cars are subjected by sudden stoppage.

from the GNU version of the Collaborative International Dictionary of English.

• noun An instrument for indicating and recording shocks to railway cars occasioned by sudden stopping.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An instrument for indicating and recording shocks to railway cars caused by sudden stopping.