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4.45 MN Deadweight Force Generating Machine (Million Pound Force Dead Weight Machine)

The largest of 6 NIST deadweight force generation machines, the 4.45 MN Deadweight Force Generating Machine can apply 20 equal force increments of 222 kN (or 50000 lbf) in tension or compression. The standard uncertainty of the applied forces incorporates the uncertainties associated with the determination of the mass of the deadweight, the acceleration due to gravity and the air density. The relative standard uncertainty of applied force is 0.0005 %.

Deadweight machines are used to calibrate force measurement devices (typically load cells), equipment that then are used to measure things like the thrust of a rocket engine or the weight of an aircraft for example. The 4.45 MN machine is not only the largest at NIST but actually is the largest deadweight machine in the world meaning much of the world depends on our machine for SI traceable large force measurements.

Pile several stories high of metal round cylinders with man climbing ladder alongside.
NIST's 4.45-million newton (one million pound) deadweight machine when fully assembled.
4.45 MN Deadweight machine
The laboratory level of the 4.45 MN Deadweight machine showing the full compression and tension mounting capabilities and overall size and height of the support structures.
Credit: NIST


Relative uncertainty in applied force 0.0005% (realization)

Capacity: 4448 kN 1000 klbf
Minimum load: 222 kN (50 klbf) 
Minimum increment: 222 kN (50 klbf)

Compression setup space:
Vertical 1.98 m
Horizontal 0.86 m

Tension setup space:      
Vertical 4.45 m
Horizontal 1.17 m

Related Instrument(s)/Tool(s)

Other NIST force generating dead weight machines:

1334 kN (300 klbf)
498 kN  (112klbf)
113 kN (25.3 klbf)
27 kN (6.1 klbf)
2.2 kN (505 lbf)

Usage Information

Access Information

Calibrations can be ordered through:

Created December 19, 2023