Mailing List flyrotary@lancaironline.net Message #16750
From: George Lendich <lendich@optusnet.com.au>
Subject: Re: [FlyRotary] PSRU - hub/prop end
Date: Wed, 9 Feb 2005 09:52:21 +1000
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Ernest,
Timken Taper Bearings are the best there are, but I'm surprised there is
only one - there's not one on the other end of the shaft?
They are in fact overkill for this application.

The nut will be for preload, remember when you put it back on, that you know
the preload number.

Again go to a bearing supply company, I have no doubt that there would be a
standard seal to fit. Who ever made this PSRU would look for standard seal
sizes.

George ( down under)

I have two more questions I'd like to get advice on.

1) The propeller is held on by being bolted to a NASCAR wheel hub.  The
prop shaft passes through the hub shaft and engages the planet gear
housing.  So basically, all  of the force pulling the aircraft along
will pass through a single Timken taper bearing held on with a large
nut.  The number I got off the bearing is 18690.  I know these bearings
are extremely robust in absorbing the lateral forces of car wheel, but
how will they hold up to the 800lbs or so of longitudinal forces from a
propeller trying to pull the hub off its shaft?

2) Oil will be fed from the top into a gallery that runs front to back.
Oil will feed into the back of the hub, travel through both front and
back bearings, and return down the side of the prop shaft. Everything is
sealed just fine, except for the front of the hub. Any ideas on how to
accomplish this?  The prop shaft is 1.250" at the point where it needs
to be sealed.  The only thing I've come up with so far is to machine a
plate to go between the hub and the prop with a recess that will hold a
seal.



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