In the early years of the 20th century, automotive and tractor manufacturers were sometimes a little on the unscrupulous side (some would argue not much has changed in 100 years). Tractor manufacturers in particular would build shoddy equipment and pass it off as a quality product from a better-known builder. One in particular was a "Ford" tractor that had nothing to do with the Detroit-based auto builder.
In response, the State of Nebraska in 1920 began requiring that every tractor sold in the state be tested to assure that it would perform as advertised. The tests were performed -- and still are -- at the University of Nebraska-Lincoln, where that fraudulent "Ford" tractor still resides. The requirement is still in place, as is the dynamometer that was used for most of the tractor testing in the past century or so.