On 14/07/14 08:50, AndyW wrote:
On 11/07/2014 13:19, gareth wrote:
Has anybody seen inside one of those slow-motion ball drives
that is 6:1 nornally, but 36:1 in reverse for a few revs?

I'm just curious as to how they work inside.

I have seen this action in compound epicyclic gearing.
Depending on the actual arrangement inside the gearbox you can lock the
ring gear, the sun gear or any one of the planetary gears to change the
ratios. For compound gearing you can add extra planetary sets on the
same shaft.

Have a look at https://wikis.engrade.com/planetarygearsetsoperati
(it looks like the URL is truncated but it does work)

Andy
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Thanks Andy , Useful reference

Frank GM0CSZ / KN6WH