lost motion
What is lost motion?
Lost motion is a common term used in piano technology. It refers to the gap between adjoining moving components on a note or pedal.
For lack of a better analogy, think of lost motion kind of like a door in a door frame. If a door fits too snugly in a door frame, there is not enough room for the door to open and close properly. Conversely, if a door is too small for a door frame, it does not serve its intended purposes. In order for the door to pass through the frame without excess friction, but also provide privacy as designed, there must be a measured amount of small space (i.e. lost motion) between the door and the frame.
The same is true in piano components that require lost motion to function as intended: If some degree of lost motion does not exist where it is meant to, parts may not properly return to rest position when a key is released, or the piano may not play properly. Conversely, and more commonly, if there is too much lost motion, there is an excessive disconnect between components, creating a loss of energy and efficiency in the piano, and making the piano difficult, inconsistent, and unwieldy to play.
What does it mean to regulate lost motion?
Regulation of lost motion is the process of adjusting the piano’s action so that the correct amount of lost motion exists between certain components, permitting them to function as designed.
If I don’t have my piano’s lost motion corrected, what is the net result?
If lost motion is not regulated properly, the piano will not play and respond as intended. As lost motion continues to move further away from manufacturer specification, notes may begin to “double-strike” (meaning you hear the hammer strike the strings twice, even though the key was only depressed once), or stop functioning altogether. Whether or not the pianist realizes what’s happening “under the hood”, this can make a piano student excessively frustrated, or drive an advanced pianist up a wall!
Why does lost motion change in my piano if it was set correctly at the factory?
The amount of lost motion in a piano changes with humidity and temperature fluctuation, compression of felt, cloth, and leather components, and as the piano is played. Even a small change in lost motion can be felt by most pianists of any level.