Re: [PSUBS-MAILIST] Seals again

[TeslaTony@aol.com]

In a message dated 10/3/00 6:50:23 PM Pacific Daylight Time, 
s_lindblom@conknet.com writes:

> The pressure on the hub is balanced by the pressure on the other side of
>  the hub. The only pressure that is exerted on the internal components via
>  the shaft is the pressure acting on on any area of the exposed drivetrain
>  WHICH IS NOT BALANCED on the other side - that is to say, the part that
>  goes through the seal. A smaller shaft will transmit less pressure. The hub
>  size has nothing to do with it.
>  
>  Draw a picture and it'll make more sense. Draw a square to represent the
>  housing. Surround it with little arrows pointing in to represent ambient.
>  Lets say each arrow represents 10 lbs of pressure. Now draw a line through
>  one side. That represents the prop shaft. just to make it clear, make it
>  protrude an inch from the side of the square.
>  
>   Now draw a line across the exposed end of the shaft line. That represents
>  (in cross section) the hub. Continue drawing the little arrows all the way
>  around both the shaft and the hub. Now, if you've spaced the arrows evenly,
>  you will notice that no matter how big or little you make the hub, the
>  arrows will balance EXCEPT FOR THE ONE IN THE MIDDLE OF THE HUB opposite
>  the shaft.
>  

That makes a lot of sense, although one thing I'd like to point out is that 
on all of the electric motors I have there is a hole on the other side of the 
motor housing with the other end of the shaft stuck into it, so if there was 
another shaft sticking out the other side of the submersible housing then 
there WOULD be a compensating arrow on the other side of the shaft.
 Now I know that something like that isn't always possible with all sub 
designs, so I guess a set of ballbearings or something