Simple Measurements

I recently had an experimental stage that the electric motor regularly stalled. When I asked the mechanical engineer how much torque was required to move the stage he was confident that the motor he found was able to lift the stage, he avoided my question. I insisted that the required torque be measured but the assembly precluded the use of a torque wrench without a lot of expensive disassembly. The disassembly might even invalidate any torque data achieved. Instead I had a machinist fabricate a lever arm that could be clamped to the drive shaft and a string and paper clip hook attached to the end of the lever arm. Lead weights were then added to the hook until the lever arm applied enough torque to start the drive shaft to rotate. The weights were weighed and arm length geometry with respect to gravity was then taken into consideration and known torques were calculated. To the mechanical engineer's surprise the stage in some positions had stiction forces 30% larger than the electric motor's rating.

Redfred, that answer is worth a GA.

A customer wanted a motorized actuator on big, brutal damper and asked what torque it needed. I wish I'd thought of weights, like you did.

I recommended a spring loaded scale, which he bought. He then had to extend the lever arm several times, welding on extensions until he got one long enough that the scale wouldn't max out without the lever moving.

Weights! Of course.

Water tube manometers and inclined manometers are still used extensively, and I've used to 'prove' that the electronic calibrator was 'working'.

sling psychrometer for relative humidity measurement: