free-running

comparative freer-running · superlative freest-running

1. Moving freely and smoothly.

   It is the Bulleid Pacifics of the Southern Region, which all observers of locomotive performance know to be among the freest running engines in the country.

   1961 November, Cecil J. Allen, “Locomotive Running Past and Present”, in Trains Illustrated, page 684

   1 more example

   As to any suggestion that Stroudley's engines were not free-running at high speed, this was of little moment with 60 m.p.h. laid down as the limit at that time.

   1941 May, “Notes and News: William Stroudley”, in Railway Magazine, page 234