Boosey & Co. N.V.A. valves (1922-1946)

Invented by Boosey & Co. employee Arthur Blaikley and patented in 1922, the N.V.A. system flipped traditional valve physics completely upside down. For nearly a century, every piston valve relied on a standard compression spring that squished downward when pressed. Blaikley’s design used an extension spring that smoothly stretched out instead. By pulling the piston rather than pushing it, the design effectively eliminated internal spring buckling, resulting in significantly less metal-on-metal friction and a remarkably quiet vertical movement.
Recognizing the high performance of this silent design, Boosey & Co. (and later Boosey & Hawkes) reserved N.V.A. valves exclusively for their top-tier, premium instruments. These elite horns were manufactured for over two decades until 1946, when Boosey & Hawkes acquired the rival Besson company and completely standardized their factory production parts.
While the N.V.A. valves performed flawlessly in the hands of musicians, they had a major Achilles' heel behind the scenes. They were incredibly complex to mass-produce, and for the instrument craftsmen who built and serviced them, these pulling extension springs proved to be notoriously fiddly and difficult to install compared to standard top or bottom springs.