X-Mozilla-Keys:                                                                                 
Jeff Spitzer wrote:

At 03:02 PM 8/26/99 -0700, you wrote:

I finally got around to getting a Timken roller
bearing catalog. IMHO tapered roller bearings are
the way to go. They are light weight for the thrust
load handling capabilities and compact.

Note that in a later post you quote the thrust load from the sun helix as
greater than what the prop will likely produce.  Yet you chose two ball
bearings for the thrust of the input shaft.

I will take a look at back to back tapered bearings for this 
application. Do you think my calculations are right for
the helix thrust?

I would suggest that you abandon the pilot in the e-shaft and add a
flywheel-end bearing to your input shaft. 

Do you mean abandon the pilot in the output shaft?
One needs a pilot in the output shaft for the sun gear
shaft.

If you do indeed mean the pilot in the e-shaft yes I think
that will work. However any bearing added would then act as a pilot
would
it not. I am a little confused on what you have in mind here.
Would'nt this limit the diameter of the bearing? I'll consider it.
can you make a sketch and send it? I am open to all suggestions.
 

 I suggest this because
planetaries are very sensitive to centering properly and the notion of
accurately aligning the whole gearbox to the e-shaft is not a good idea
IMHO.  Note that the clutch center is capable of dealing with as much
misalignment (more) as the plantaries if done right.  Perhaps you would now
choose to use tapered roller bearings here too.  I'm not sure you would
want to.  

The differential CTE of the aluminum housing vs. the steel input[output?]
shaft causes the bearings to either loosen or tighten with temp.
Tightening is not bad as long as you let it warm up before you run it hard
(and build it a little loose at room temp).  Loosening is very bad indeed
unless you build it very tight.  Either way when the bearings are loose the
shaft will misalign.  

Jeff Spitzer

I knew you would say that. I am going to warm the housing to 200 
F when I adjust the tapered roller bearings preload. Other options are
to make the output shaft out of aluminum or the housing out of
steel. A steel housing is not a bad way to go as it could be rather
thin wall.

I am counting on the low modulas of elasticity of the planet carrier
to adjust the centering. I think that is what Ford had in mind when
they choose aluminum in the first place. Chrysler uses steel and
they have had a lot of trouble. GM uses steel or cast iron
but I will bet they hold tolerance real close. Another factor
in the centering is the output bulkhead is splined to the
ring gear so the ring gear can float somewhat relative to
the sun gear and planet carrier.

Thanks for your thoughts on this Jeff.

Paul Lamar
 
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