Sentence:  In 1870 at Montrose, N.Y., the New York Central made the first installation of a track pan and scoop to permit locomotives to take water on the fly. Since these installations invariably were in tiny communities, and since they permitted locomotives literally to “<WSD>jerk water</WSD>” 
Meaning of the word marked with <WSD> tags:  To scoop water from a track pan mounted on the tracks directly into a steam engine's tank without stopping.