Hi Greg: You are correct, they are mounted to a plate with a hole in it
large enough to let the output shaft pass thru it. The unit shown in the
ebay add is missing a large bevel gear which mounts to the splined
output shaft. Most people weld a bushing to the bevel gear for attaching
the tubular mast and the bevel gear takes the vertical load. It is
possible to use the splined shaft for output by machining a mating
You do need a direction indicator. If the bevel gear is on the unit,
some people make a large gear out of sheet metal the same diameter which
will mesh with it to rotate a potentiometer or selsyn. Some of the PP
mod articles have dimensions so you can make it with a drill and a file.
I have used sprocket and chain drive as well as a small dial cable and
pulley arrangement to turn a potentiometer.
It is essential that the top of the unit and the indicator you use be
protected from weather. I have seen PP motors in flea markets which were
not protected and the bevel gear and the ball bearings beneath it are
M2 sells a modified version of their OR 2800 control and indicator box
for PP motors. You attach a small magnetic pickup to the motor shaft
which generates pulses as you rotate and the unit supplies power for the
motor.. The price is around $500 I believe.
73, Dan, N5AR
Greg Gobleman wrote:
> I was looking at the photos of this prop pitch, not having seen one mounted
> I was trying to figure out how they are installed. I assume the flat plate
> area is bolted to a stationary plate. Is a notched piece made to adapt to
> the mast pipe? I also have read of needing to rig a directional indicator
> of some kind. Any info on that? May I assume that the control box and
> indicator will probably cost as much as the rotor?
> Greg K9ZM
> Towertalk mailing list