Load Cells: There’s Something Happening Here

by Michael Shade, IQS Editor

Michael Shade Author Pic

In October of 1967, political activist Abbie Hoffman and other luminaries of the American countercultural and anti-war movements marched on Washington D.C. with one goal in mind: to levitate the Pentagon with psychic energy. As Beat poet Alan Ginsberg led the crowd of demonstrators in Tibetan chants, Hoffman claimed that the group would levitate the Pentagon until it turned orange and began to vibrate. While then defense secretary Robert McNamara watched the protest unfold from his office window, many questions were probably going through his mind. Not the least of his questions would have been, “What will Johnson do to me if they actually levitate this building?” This would be a reasonable expression of anxiety, considering President Johnson was known to lift up small dogs by their ears. Nowadays, secretaries of defense need not worry about the levitation of the nerve centers of our nation’s military-industrial complex; their stability is measured carefully by load cells.

Load Cell Sample

Photo courtesy of Strainsert Co.

The North American Aerospace Defense Command (NORAD) and its fortress deep beneath Cheyenne Mountain in Colorado Springs would have nothing to fear if confronted with chanting, levitation-threatening anti-war demonstrators – it’s tough to surround an entire mountain with people. But the greater challenge would be competing with the complex’s suspension system, which, according to an exclusive History Channel feature, is designed with an impossibly complex combination of enormous springs, load sensors and strain gauges that is built to withstand earthquakes. If a technician sneezes in one of NORAD’s super-secret sub-basements, one of the facility’s load cells will probably register the shock.


Photo courtesy of Strainsert Co.

A load cell is a measuring device that is used to register forces of compression and tension. They are transductive measuring devices, which means that they convert mechanical force into an electrical signal that gets interpreted by a computer or expressed on a gauge. While the bit about the sneezing technician might be an exaggeration, if, for example, a shift in the tectonic plates near Colorado Springs gave Cheyenne Mountain the shivers, the resulting compression and extension of load sensors would send signals to monitoring systems. A load sensor works by telling an external monitoring system the extent to which it is deformed by a force. The stronger the compressive force, the more deformation the cell experiences. Outside of the national security context, load cells sacrifice their shapeliness for more inconspicuous purposes like pallet weighing in warehouses and ingredient weighing in food processing (which requires miniature load cells). Force sensors weigh big rigs at highway weighing stations, and force transducers can be used to measure the load-bearing capacity of bridge-building materials. One variety of load cells (pressure sensors) can even be used to measure gas pressure in piping systems and engines.

Custom Load Pin

Photo courtesy of Strainsert Co.

Industry finds ways to engineer uncertainty out of our lives, and markets and politics are nourished by that stability. Load cells keep overweight trucks off of our roads and bridges. They are harbingers of impending catastrophe in our infrastructure, and they weigh our food without contaminating it. The measure of our ignorance of the quality of the commodities traded in our economy is the function of how catastrophic the consequences will be when a bridge collapses, food poisoning strikes a community or a secret bunker is levitated by hippies. Load cells are great indicators of what’s happening, but they’re useless if no one checks the gauges. Fortunately for us, they make themselves easy to read. In some cases, they’re even connected to alarm systems. How appropriate would it be if NORAD’s load cell alarm was the song Stop – Hey, What’s that Sound?

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