One million pound stack: recalibrating the world’s largest deadweight machine

Published On: February 8 2024

In 1965, the National Institute of Standards and Technology (NIST) deadweight machine became the world’s largest deadweight machine. The three storey, million-pound stack of steel disks was created to calibrate load cells used to measure large forces in the space and aeronautics sector.

“NIST’s Million Pound Deadweight Machine is used to calibrate sensors that measure enormous forces, like those created by the thrust of a rocket or jet engine.”

However, over time the machine in Gaithersburg Maryland has lost accuracy, so the machine has undergone major refurbishment and maintenance in 2017, the first time since it was initially built in 1965.

“The year-and-a-half-long saga involved dismantling, cleaning, restoring, and recalibrating about half of the stainless steel discs in the three-story stack of weights.”

Now back in action, the machine can produce forces of up to 4.45 million newtons (equivalent to one million pounds-force).

 

Measuring the cost of space travel

The money involved in transporting items into space is positively eye-watering, so literally every gram of cargo has a price tag. According to NIST:

“It costs around $10,000 per pound to lift an object into space. With that kind of price tag, it’s important everything works on the first attempt. For any rocket launch to be a success, the force generated by the rocket has to be known and controllable, but with rockets routinely generating force measured in the Meganewtons, obtaining an accurate measurement is a herculean challenge.”

The forces in the deadweight machine are created by hanging the machine’s stainless steel weights from the load cell being tested. Each disk is a little less than 10 feet wide and weighs just under 50,000lbs. The disks lock together so when lifted, they hang straight down. The machine is remarkably accurate, with the relative standard uncertainty of applied force just 0.0005%.

For more pics, specs, and a video, check out this article on NIST’s website.

 

Need your load cells calibrated?

At the Load Cell Shop, we can calibrate most load cells and indicators. We provide full system calibration at our manufacturing base in Reading UK for most types of load cells and load cell amplifiers. All our calibrations are traceable to national standards, and If you require a Certified Calibration Certificate, we can have your load cells calibrated by a UKAS accredited lab. Contact us with your requirements:

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