Low head hydro link

[keithturtle]

Yeah, Bryan, that idea seems to have merit... I'm right in the middle of this part of the build so I'll look into it.  I do have a chunk of teflon that could make the bushing.  I wonder if building up some brass on the shaft then turning it down would work.   My original approach was to use the vacuum created by the water rushing through to pull air into the bearing's housing and thus keep water out.


Turtle, still at it

[keithturtle]

Just found this Vesco plastics site.   Wonder if these are available in sizes we need?

http://www.vesconite.com/industry/HydroPower/HydroPower.htm

Turtle

[wpowokal]

vesconite is used as bearings in ski boats so seems the go.

[WoodWaterWheel]

I've looked at using some of the high wear slipper nylons out there and even machined a few along with Oilite bronze bushings.     The fact that they stay wet helps with the potential heat (helped with the nyltron but not the oil impreginated bronze) but grit in the water wears at them requiring frequent replacement, that's why the competing units ship a replacement lower bearing with each of their units.          The slack induced due to both vertical and horizontal wear places additional stress on the upper bearings in the PMA.       I tried a mid point shaft bearing but it made removal of the impeller very hard and added one more location where tight tolerences were required adding to manufacturing costs.       By using a shielded angular bearing mounted under the impeller's skirt you keep it out of 95% of the water flow and in a low pressure area.        In addition to this along with the way the entire unit is built allows for the lower bearing to be replaced in 3 minutes once a year.          Also by eliminating the middle bearing you suggested the unit can be pulled apart to remove something large like a turtle in less than a minute.        Smaller or soft debri like sticks, leaves, or a small fish gets chopped up by the stainless steel impeller.       Yes you want a screen at the intake but if something does get past the turbine will usually clean itself unlike a pelton ot turgo which even a small leaf can plug it up.         An additional feature to my design is that unlike a Kaplin which will vortex and shut down requiring a restart after water flow increases my units just decreases power output to match water flow.       If the water totally stops or gets below 450 gpm my turbine stops but once water flow gets over 450 gpm it restarts automatically.        Now I just need some retailers to sell them for me,       I've sold a few with good results but would really prefer to leave the selling to established retailers.   
Spencer     

[keithturtle]

the unit can be pulled apart to remove something large like a turtle in less than a minute

<GASP>

I bought the vesconite, trimmed in gold.

Looking at keeping the design so there is a low pressure zone around the bushing, possibly something like scotchbrite pad where the water passes, don't know yet.

I have not yet settled on a wheel design yet, either.  I do have several 5" long hubs welded up upon which to weld the vanes.   Leaning more toward a reaction francis type rather than kaplan.  With the very low head I'm dealing with ~1 meter, I realize my TLAR engineering approach (That Looks About Right) is going to cost me dearly in time invested in trial and error.

While I'm not out to pirate anyone's idea or product, any guidance would be very much appreciated at this point.   Forming the Francis buckets is within my reach using 16 ga sheetmetal and a press, though the dies will take a while to fabricate.

Turtle, still at it