Ramsbottom safety valve
noun
Rams·bot·tom safety valve
ˈramzˌbätəm-
: a safety valve used especially on locomotives in which two valves are pressed down by a single spring attached to a crosspiece prolonged to form a hand lever by which the valves may be eased up to test their adjustment
Word History
Etymology
after John Ramsbottom, 19th century British mechanical engineer