Prop-pitch

[Frank Donovan]

Hi Phil!

Yes, the small prop-pitch has a 9576:1 reduction ratio.  The most
desirable version uses a plug-in motor easily removed by unscrewing a
retaining ring.  A less desirable version also uses a plug-in motor held
in place with a bolt-on retaining ring.  An undesirable version uses
a motor that is mechanically and electrically very difficult to remove
from the gearbox (I do not use these!).

The modification you refer to involves a modification to the output
gear/shaft and the final planetary gear mechanism.  If your prop-pitch is
"stock," the output shaft will include a gear that couples into the
planetary gears.  If it has been modified, the gear teeth have been cut
away from the output shaft and the shaft has been bolted to the body of
the planetary gear mechanism.  This is an awful modification that
ruins the usefulness of the prop-pitch motor.

A very common problem with prop-pitch motors is failure of the rubber seal
for the output shaft.  After fifty year or more, the rubber seal will have
dried out!  As a minimum you should replace the seal, but much better
is to use an additional box to prevent water entry entirely.  K6NA sells
the required hardware to enclose your prop-pitch and prevent water entry
that will surely destroy your precious prop-pitch.

You can reach Glenn at rattmann@cts.com

73!
Frank
W3LPL
donovanf@sgate.com

On Thu, 16 Jan 1997, Phil Duff NA4M wrote:

> I recently obtained a used prop-pitch motor. I believe it to be a
> "small" prop-pitch based on the attached metal tag which states the
> gear reduction to be 9576:1
> 
> I've partially disassembled it and my question is how to determine
> if this prop-pitch has the dreaded "modification" that changes the
> rotation speed at the expense of the units braking torque?? I'm
> assuming this to be a change of some type to the gear mechanism. 
> 
> 73 de Phil NA4M  na4m@texas.net
> 
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