>From: Victor Tikhonov <
[email protected]>
>Reply-To: Electric Vehicle Discussion List <
[email protected]>
>To: Electric Vehicle Discussion List <
[email protected]>
>Subject: Re: [EVDL] The Short and Tall of it
>Date: Sat, 25 Aug 2007 10:52:04 -0700
>
>In the US established notations, many things like that are backwards
>vs what you'd intuitively think. If something is bigger, naturally
>you'd assign a bigger number to it, sort of 3 mm is bigger than 1mm.
>(or something of 3 feet is bigger than of 1 feet).
>
>Yet, consider wire diameter - more gauge number - less diameter.
>Instead of simply specifying diameter (or crossection area),
>AWG system was established where wire diameter associated with
>a number. larger number - smaller diameter. Now you got to remember
>which number is want diameter.
>
>Similar - for sand paper. You'd think more number - larger grain
>(the number just represents size of grain), but it's opposite.
>
>Similar for bolt/nut sizes.
Victor - larger screw sizes DO have larger numbers. a number 10 screw is
larger than a number 6.
As for threads per inch, that is quite logical and easy to understand. A
10-32 screw has 32 threads per inch. That is both easy to understand and
very easy to measure. ( counts the threads in one inch)
>
>
..
..
..
>
>So you're stuck with "taller" gear even though reduction ratio is lower.
>Don't apply logic here, there isn't any (or rather, backwards to
>intuitive understanding), just established and settled
>conventions. It is very American thing.
"Taller gearing" has become common usage simply because it IS so intuitive
and easy to understand. A taller person ( with longer legs) goes faster for
the same pace ( steps per minute) . A "taller" ratio gear means the car
goes faster for the same engine speed.
The first time I heard "taller gear" I knew what it meant. That would not
be true for the term "higher" gear. That would be ambiguous, because it
could mean numerically higher, or that the car went faster for the same
engine speed.
Phil
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