Joe writes:
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> The theory I have is that as the engagement hub outer collar is slid
>towards the gear, it engages the synchro, then as it travels further
>(during the act of shifting) it slides the synchro towards the gear.
> Does This act of sliding it towards the gear cause the inner cone of
>the synchro to rub (for lack of a better term) the gear, slowing it
>down,
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Yep, or speed up as the case may be, Its really a little cone clutch. Also
the cluster and input shaft speed is controled at the same time by that
little clutch so that at the time you slide the synchro ring into engagment
everything is turning at the same speed. The grinding you hear if things
are done wrong is actually the 'dogs' on the gear grinding against the
synchro hub splines not the gears themselves (which are always in mesh),
wearing the sharp points down and eventually causing hard shifting and in
worst cases jumping out of gear.
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>slowing those little teeth so the engagement hub outer collar can mesh
>more smoothly? Am I to understand that all 110 horse power (if it runs
>that well) of the engine is transmitted (now I see why they call it that)
>at this point through those tiny little teeth that the engagement hub
>hooks up to?
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Right again, those tiny little 'dogs' are the only thing between you going
and not going, pretty amazing isn't it?
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Then why are the other teeth on the gears so large?
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Gear design is very complex, but when you look at it simply (if possible)
the 'dog' engagement, while appearing small is actually the area of all the
little dogs together while the gear has only one tooth at any one time
(remember I'm simplifying here) in contact to distribute the load. Helical
gears are used rather than straight cut because they run quieter than
straight cut gears at the expense of slightly more friction (sliding action
over slightly longer tooth contact) and heat. That's kinda the theory and
VERY simplified in a nutshell. . .
Hope that clears things up a bit -
Barry Schwartz
Bschwartz@encad.com (San Diego)
72-V6 Spitfire (daily driver)
70 GT6+ (when I don't drive the Spit)
70 Spitfire (project on hold for now)
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