[Spridgets] How it's made. Episode 498 Judson Rotor.

Dean Hedin dlh2001 at comcast.net
Thu Dec 20 14:23:35 MST 2012

Having the vanes mounted sideways (like Judson) reduces the centrifugal
force on the tips contacting the bore by
reditributing part of this force to the side of the vane which has more
surface area.

The vane pump in the article is something used in the oil & gas well
industry.  Hard to tell how big it is, but it probably spins slow
compared to the Judson.  It could be that Judson had a patent on that
arrangement but I am doubtful of this. 
It could also be that the designer of that oil well gas pump does not know
about the advantage of the,
dare I say,  "Swastika" looking arrangement. 

The thing is - this "side wear" is exactly why I am making a new rotor.
All the used rotors I have seen have the slots worn out like this.
The hope is that the hard 7075 material, combined with the more modern vane
material will make this issue go away, 
or at least be greatly reduced. 

When the rotors wear out like this the unit becomes noisy, puts out less
pressure,  and any new vanes installed wear out quickly.   

BTW, I done did it... at least one rotor is almost completed.


I still can't believe I pulled this off.  It took a long time to cut those
dang slots. 1.5 hours each.

From: Tim Collins [mailto:thcollin at mtu.edu] 
Sent: Thursday, December 20, 2012 11:09 AM
To: Dean Hedin; spridgets at autox.team.net
Subject: Re: [Spridgets] How it's made. Episode 498 Judson Rotor.

Tell us why the Judson rotor uses tangentially oriented vanes while the
rotor shown in the brochure uses radial vanes?

Tim Collins

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