Steinway’s action

Theodore Steinway’s contribution was significant. He added an escapement and a damper to the German action in 1875. These mechanical refinements would prevent pianists from losing motion between the keys and the hammer for the greater part of its journey to the string. The lightness of its action increased, the keys being depressed by a weight of about an ounce, half or a third of that required today. The hammers were covered by leather, in returns producing a more beautiful, even, and thin timbre. This leather coverage has a further advantage as the wedge-shaped dampers can easily stop it; hence, preventing the hammers from bouncing back onto the strings just like the upright pianoforte’s action. Because of these advanced technological characteristics, the pianists were able to have a more direct control of the pianoforte.

Explanation on this action's mechanism:
This action is constructed on a frame of metal tubes filled with hardwoods. This is to adjust to a bigger and heavier hammer head that is used on the pianoforte. While most of the parts are fixed on the metal frame like the Erard’s action, it is left with the hammer and the key that have the flexibility to move. When the key is depressed, the back check will push the hammer head upwards to strike the strings. As the hammer head is directly being pushed upwards, this, results in a more reliable and sensitive touch.