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Old October 11th 18, 08:36 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Default "torque wrench" pump/compressor

On 10/11/2018 1:53 PM, Theodore Heise wrote:
On Thu, 11 Oct 2018 09:27:02 -0700 (PDT),
Frank Krygowski wrote:
On Thursday, October 11, 2018 at 5:00:33 AM UTC-4, John B. Slocomb wrote:
On Thu, 11 Oct 2018 08:54:38 +0200, Emanuel Berg
wrote:

Just out of curiosity, is there a "torque wrench" pump or
compressor? I.e., you would screw on the presta valve, set
the gizmo to e.g. 35psi, engage it, and instead of watching
the indicator, automagically at the right level it would
stop?

Most of the gas stations here use an air station that you can
set for your desired pressure and then just plug the hose onto
the tire valve
- there is a little clamp to hold it there. When the tire is
inflated to the specified pressure the inflation stops and a
bell rings.

Since they aren't manufactured here I had assumed that the
rest of the world had them too.


My experience from 50+ years ago says not to rely on those
things, although I suppose they may be different now.

Back then I blew a tire off the rim with one. I suspect the
problem was the volume of each pumping stroke. In a large sized
car tire, the volume surge with each big stroke would be
absorbed and barely raise the pressure. In a low volume bike
tire, it caused an explosion. That's my guess anyway.

I usually inflate using a manual floor pump with a gage. It's
easy enough to stop pumping when the dial reads the desired
temperature.


Don't you mean, when the dial reads the desired foot-pounds?


Oh geez, my mistake!

But: Neither! I stop when it reads the desired PRESSURE!

Around here we use psi = pounds per square inch. Weirdly enough, my
pump's pressure gauge is also graduated in kg/cm^2. I would have used
that as a bad example in my courses, since kg is properly used to
measure mass, not force. And pressure is force per unit area.

(This indicates that the SI system gets misused as much as the U.S. or
Imperial system.)

--
- Frank Krygowski
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