Jerry Foster wrote:
"Jeff Wisnia" wrote in message
...

snip

I believe with all false modesty that it's generally easier for a EE to
understand and analogize (izzat a word?) to things mechanical than it is
for someone from the nuts and bolts side to do in the opposite direction.

That's probably because our maker, or evolution, gave us eyes, ears and
the other parts of our nervous systems which let us observe and feel
many things about structures and machines. Lifelong observation helps
us understand mechanical things more intuitively than an unschooled
person with no test equipment observing things in the world of
electronics can. (Nasty shocks, blinding arcs and the acrid smell of
burning insulation excepted.)



As an electrical guy who has been around almost as long, (I'm not quite
retired yet...), I'll offer a simpler viewpoint. No one can see what goes
on inside, for example, a transistor, so we develop an ability to visualize.
Test equipment provides a small window into bits and pieces of a circuit and
from that, we infer everything that is happening.

A good mechanical guy develops a similar skill: the ability to look at,
say, a gear box and envision what is happening inside of it, even without
ever having seen the insides of it. One simply understands what HAS to be
in there.

Which reminds me (drifting a little away from the topic at hand, but a fun
exercise for folks who like to visualize such things...): A friend of mine
once had a little device, about the size of a postcard, a little less than
an inch thick. It had two shafts coming out the side, call them shafts "A"
and "B." If you turned shaft A clockwise, shaft B turned clockwise at the
same rate. If you turned shaft A counter-clockwise, shaft B turned
clockwise at one fourth the speed of shaft A. If you tried to turn shaft B,
it wouldn't budge. The case was rivited and couldn't be opened. (I admit
it took me quite a while before I figured out how it worked...)

Jerry



There's probably a much easier way, but if I had to come up with a
design approach which satisfied the functional description in less that
five minutes, I'd say this:

Use two roller clutches to separate the CW and CCW rotations of shaft A,
then step up each clutch's output with "speed up" gearing, say 1:10 on
the CW clutch output one and 1:2.5 on the CCW clutch.

Then use two more roller clutches to merge the outputs of those trains
into the worm shaft of a 10:1 worm gear reducer. The worm wheel shaft is
shaft B.

The worm gearing would prevent shaft B from rotating if you tried to
twist it.

Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."