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Unread 10/24/2003, 05:14 AM   #25
thunt
Registered Member
 
Join Date: Jan 2002
Location: Devon, UK
Posts: 60
No drawings, just the pictures already posted.

I allowed some slack in the positioning of the impellor. It can slide in and out by about 1/4". When its running the right way, its pushing itself back into the powerhead and so stays in place.

When it runs the wrong way, the propellor is trying to pull the impellor out. As I've allowed it to rise by 1/4", this makes the prop hit a stop, which in turns forces the powerhead to run the other way.

The vanes of the prop are also angled such that when it runs the wrong way, there's a leading edge that will hit the stop. When it runs the right way, it just glances of the stop and re-seats itself.

Hope that makes sense.

Tim


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