An torsional pendulum is a simple and convenient way to measure the polar moment of inertia of rotating components. Here is a tester I created for measuring the
inertia of road wheels.
On another occasion I built a much smaller tester when I was designing the drive pulley for an A/C compressor. This pulley was to be after-installed to the existing engine crankshaft pulley and the polar inertia of the
combined system was important.
