synchromesh
/ˈsɪŋkrəʊmeʃ/noun
mass noun
- a system of gear changing, especially in motor vehicles, in which the driving and driven gearwheels are made to revolve at the same speed during engagement by means of a set of friction clutches, thereby easing the change同步齿轮系。
词源
1920s: contraction of synchronized mesh.