By this is meant the keys and all those intricate parts which convey the motion of the key to the hammers which strike the strings, and the dampers which mute them.
The requisites of the action are as follows:
The keys must descend quickly and easily at the touch of the performer, giving quick response.
The weight of the hammer must be properly proportioned to the strings it causes to vibrate.
The hammer must rebound after striking the string. (Where the hammer remains against the string, thereby preventing vibration, the term “blocking” is used to designate the fault.)
The action must be capable of quick repetition; that is, when a key is struck a number of times in quick succession, it must respond perfectly every time.
After striking and rebounding from the string, the hammer should not fall to its lowest position where it rests when not in use, as this would prevent quick repetition. For catching the hammer at a short distance from the string, a felted piece of wood suspended on a wire, called the back check, rises when the key is depressed, and returns when the key is released, allowing the hammer to regain its resting position.
A damper, for stopping the tone of the string when a key is released, must leave the string just before the hammer strikes, and return the instant the key is released.
A means must be provided for releasing all the dampers from the strings at the will of the performer. The loud pedal, as it is called, but more properly, the damper pedal, accomplishes this end by raising the dampers from the strings.
In the square and the grand piano, the action is under the sound-board, while the strings are over it; so the hammers are made to strike through an opening in the sound-board. In the upright, the strings are between the action and the sound-board; so no opening is necessary in the latter.
The “trap-action” consists of the pedals and the parts which convey motion to the action proper.
QUESTIONS ON LESSON II.
1. What have been some
of the salient obstacles necessary to
overcome in producing the perfected piano?
2. Of what use are the dampers? Explain their mechanical action.
3. Mention several of the qualities necessary to a good action.
4. Describe the building of an upright piano.
5. Contrast the musical
capacity and peculiar characteristics of
the piano with those of the organ, which has the same keyboard.
TECHNICAL NAMES AND USES OF THE PARTS OF THE UPRIGHT PIANO ACTION.