Ken Welter wrote:

   Been thinking about it and I think that following the Ross design
of mounting the planet solid on the prop shaft, the problem is that
any play at all will result in uneven loading on the gears and even
with needle roller bearings there is going to be a bit.
  Why not spline the prop shaft and and slip the planet on as it was
designed and leave it unmodified so that there is a bit of float in
it.
  Also I think this may be easier to incorporate into the hollow prop
shaft design that you have mentioned Paul.

  Another advantage to this is easy replacement just slip it out and
slip in a new one and a friend that works a trany shop said that he
would buy good used ones from me for half price of new so I would
lean to replacing them every hundred hrs or so just for piece of
mind, I cant believe how cheep these planet sets are as I have found
the new six pinions for $68.

   Ken

The stress goes up as the diameter goes down to accommodate a spline.

The stress for solid shafts are proportional to the fourth power of the

radius.

That means roughly a one inch radius shaft to the fourth power is just one

but

two inch radius shaft to the fourth power is sixteen or sixteen times

stronger!

Count em... SIXTEEN TIMES STRONGER!  Now for a four inch HOLLOW shaft
compared to a 2 inch solid shaft it is not quite this good but it is
in the same ball park.

This is why I suggest making the inner end of the
hollow shaft the same diameter as the shaft circle of the planet carrier.
It is load path analysis. The load path length is minimized.
That leads to the lightest weight design. The load comes right out
of the pinion shafts right into the large hollow prop shaft.
There is little load on the planet carrier itself in this design.
All it does now is mainly hold the pinion gears in alignment.

If there is any slop in the prop shaft needle bearings the planetary gears

will

self center anyway. Best to precision machine the whole thing.

Any slop in the heavily loaded spline will lead to excess wear in the

spline.

Just another spline to add overall  torsional slop.

Same goes for the prop end. It makes no sense to go down to a 1.25 inch
diameter prop shaft and then back out to a 5.5 inch diameter prop bolt
circle. The torsional and bending stresses are much much higher in
a 1.25 inch shaft than they are in a 5.5 inch shaft.

Same goes for the ring gear. Don't use a ring gear bulkhead with splines.
Lock the ring gear to the housing with six set screws screwed into
taped holes in the housing. That maximizes the diameter of the
ring gear fixing device minimizing the stresses.

Paul Lamar

Ken,
Slausons has regular specials on just about everything - I just ordered 3
NEW 2.85 planetarys at $38 each, their regular price is only $63- $68.
The 2.17 is double that price for some unknown reason, but I will find out -
tell Luke I sent you and you want the right price.
I don't know if the special is still on, but you could ask!
George (down under)

 
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