On 24 Oct 2007 23:53:08 GMT, Dave Hinz wrote:

On Tue, 23 Oct 2007 16:37:57 -0400, Brian Lawson wrote:

I got one wrong. And I couldn't believe it!!!!!!!! All my working
life had to do daily with worms and worm-gears, and I GOT IT
WRONG!!!!!! The Union will want my Mechanics card back!! Thank
goodness I retired before they found out how dumb I really was!!

I've looked at that worm gear question another time after a respected
coworker of mine also got it wrong, and I'm not convinced that the
"right" answer is right. Either that or there's some Escher kind of
thing going on with that drawing.

Hey Dave,

Naw, they have it correct. It was just me.

Just for fun, draw a series of parallel diagonal lines, top left to
lower right. If that were the "threads" of a screw, you would be
drawing a right-hand thread, with the head of the bolt on the
right-hand side. Now pull the top of the lines "down", as indicated
by the arrow showing rotation direction on the drawing. That moves
the "centre" of each line to the left. The same motion if it were a
bolt would be to loosen or remove the bolt. The "bolt" in this case
is trapped, and while it can turn, it cannot move left or right, so
the force is applied to the nut (worm-gear), and would therefore push
it away. Pushing "away" on the top of the worm-gear causes it to
rotate Counter-Clock-Wise.