What is graceful movement? How do everyday things move gracefully, and what can we learn to bring grace to our own movement? Consider three examples:

Transmission Lines

Power Transmission Lines are used to distribute electrical power from generation facilities to homes and businesses. They provide a redundant network for power distribution; everyone should get reliable power even if parts of the transmission line network are temporarily shut down.

In the US, overhead transmission lines come in sets of three, and they usually deliver three phase power. The three power cables are held at uniform tension, and the distance between the three cables is precisely maintained throughout the entire transmission network.

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Wind can cause the individual cables to vibrate; those vibrations can wear the cables out much faster. Cables moving individually could also create electrical noise and lower the quality of power in the grid.

Engineers use Stockbridge dampers to control mechanical vibrations on each segment of the cable. In this picture, there are a total of eight stockbridge dampers visible. These dampers are “tuned” to optimally absorb the particular kinds of wind-induced vibrations that the cables encounter.

These dampers are a classic loosely-coupled design; it’s also a bit counterintuitive that such a small widget could effectively control the vibrations on a long length of cable, but they do the job. These dampers are ubiquitous on transmission lines, but they were invisible to me until I started researching damping systems. Next time you’re near a transmission line, look for the Stockbridge dampers. And watch how the transmission lines move so … gracefully.


Door Closers

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Many doors at homes and most at businesses have some sort of auto-closing mechanism. A well-tuned door-closer will positively but silently close the door. A door-closer has two main parts: a spring to close the door, and a damper to prevent the door from slamming shut. Engineers would call a door-closer a classic “mass-spring-damper”. Electrical engineers may note circuits that function in a similar fashion; electrical vibrations are modeled similarly to mechanical ones.

Everyone is familiar with springs, but many of us have never played with a damper. Dampers usually work by having a piston move through a cylinder of fluid — the “damp” part of a damper. When a diver enters a pool of water, the water rapidly damps — or slows down — the movement. If you put a tuning fork into a glass of water, the tuning fork will rapidly stop moving. In all cases, the fluid is absorbing the motion from the thing being damped.

What happens to the energy of the motion? In all of the examples above, the damped motion gets converted into heat. The rise in temperature depends on how much motion was damped and the size of the reservoir of fluid. A swimming pool would only get a tiny bit warmer from hundreds of divers, but door-closer could heat rapidly if a door were continually opened and closed for a couple of minutes. Heavy-duty dampers are designed to deal with more open/close cycles will be able to work correctly over many more open-close cycles per hour than a light-duty damper. If you see signs that fluid has leaked from a damper, that’s a sign that it needs to be maintained and/or upgraded to a more robust unit.

Almost all door closers have simple controls to adjust how they close. They have separate adjustments for the spring constant and for the damping factor. If a door isn’t closing the way you like, it’s usually very easy to adjust.

Pianos

Pianos were created in the early 1700s. At the time, the predominant keyboard instrument was the harpsichord. Pianos rapidly eclipsed the harpsichord in popularity and gained widespread acceptance as a solo, ensemble, and accompanying instrument. Pianos were originally named a pianoforte for their ability to play both softly and loudly; the name was eventually shortened to its current (and nondescript) name.

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The first great innovation of the piano was a mechanism where the keys could be struck that allowed for both a louder and softer instrument than earlier keyboard instruments. Each key’s action is designed to strike the appropriate strings then rapidly move away to allow the strings to vibrate freely. Each hammer is wrapped with felt, a damping material, to give a clear and clean sound. The action is pressure-sensitive; pressing a key firmly will strike the string more forcefully than pressing a key gently.

Keyboard instruments have each of the strings tensioned (or tuned) to vibrate at a particular frequency. How long is a particular string allowed to vibrate? It depends on the particular instrument. Hammered dulcimers allow the strings to continue to vibrate until they damp on their own—over a dozen seconds for most the strings. Many of a dulcimer’s strings could be vibrating at the same time. These dissonances may sound strange and disagreeable to listeners only familiar with “modern” string instruments.

Both a harpsichord and a piano will damp a string when its key is released. The piano adds a sustain pedal which temporarily overrides the damping mechanisms of the individual strings. Pianists can strike over a dozen keys, sustaining a full and broad chord, and stop all the vibrations at once. A second pedal, the soft pedal, shifts the piano’s mechanism to strike only 2 of the 3 strings for each key and instantly decreasing the volume of the piano. The sustain and soft pedal mechanisms are the second great innovation of the pianoforte.

From these examples…

Door closers show that tensioning and damping are complementary and distinct components of movement. Adjusting the tension is different from adjusting the damping (and vice versa).

Stockbridge dampers show that a little bit of damping can go a long way. Through body/mind exercise, a small bit of development in our damping mechanisms can dramatically enhance our gracefulness.

The pianoforte shows that more damping is not necessarily better. Sometimes we need a lot of control and sometimes we should let everything run free. Graceful movement is about our ability to adapt our control/damping mechanism to be in concert with what we want in the moment.

What other examples of graceful movement do you see? What can you take from those examples and apply to your posture and movement?

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