One Day in 1932 Josef Hofmann, the American pianist, composer and inventor who had already spoken of the Steinway’s “extraordinary perfection of action,” came to Steinway Hall and said, “It isn’t quick enough: can’t you make it still more sensitive, still more responsive?”
Hofmann’s challenge was the impetus to Steinway becoming the most responsive and sensitive of any piano made. Frederick Vietor, grandnephew to C. F. Theodore Steinway, fulfilled Hofmann’s request by creating the Steinway Accelerated Action, enhancing the Steinway action to respond to the touch instead of being forced into action. Today, the Accelerated Action is found on all American-made Steinways.
Laboratory tests have proven that the keys on a Steinway can repeat 13% more quickly than any other piano. The same features that allow for this faster repeat also provide a much more sensitive, responsive keyboard, an aspect that can be appreciated even by beginning pianists.
The keys of a Steinway are constructed of Bavarian spruce. The quarter-sawn maple action parts are mounted on a Steinway Metallic Action Frame, which consists of seamless brass tubes with rosette-shaped contours, force fitted with maple dowels and brass hangers to assure the stability of the regulation.
Want to read more… you can find the full artickle at steinway.com