Dean,
It makes no matter if your keeping 200 PSI in or 200 PSI out. Your
seals still have to be able to stand up to a 200 PSI pressure differential so
why pressurized the pod? Why not just build the pod a bit heavier to
take the compression, and don't bother with putting pressure in it.
Carbon against ceramic seals are best if your going to be operating in the 200
PSI range.
For most applications with small horsepower thrusters, the motors ball
bearings can handle the thrust load. But for 12 Hp you might want to dig
deeper. Determine what bearing is now on the thrust end of the motor
shaft and find it's thrust rating at the RPMs your operating at. It
may be high enough since you have almost no side loading on a prop
shaft.
There should be bearing numbers on each bearing. If not, measure
ID, OD and thickness, count the number of balls in it and contact a bearing
supplier. They should be able to help you with it's load ratings. The
load is derated as the RPMs go up. On the other side, a bearing can
handle a very heavy load for a shorter time. You won't need it to
operate for 20,000 hours. A few hundred hours of operations is more
then most Psub thrusters will see in their life time.
From there it's simply a matter of comparing the pounds of thrust you'll
get from 12HP spinning the prop your using to the bearings thrust rating.
Dan H.
----- Original Message -----
Sent: Monday, January 26, 2009 3:56
PM
Subject: [PSUBS-MAILIST] motor pod
seal
I am trying to figure out what to use for a shaft seal for my
main motor
I am planning on manually pressurizing a pod made from and air
compressor
tank. So I guess what I am looking for is a shaft seal that
will take up to 200 psi
internal pressure, this is way out of my
expertise.
Any suggestions on what to look for
That and do any of you use bearings for the propeller shaft?
All I seem to see
are just bushing types, I am using a 12hp dc motor and it seems
to me that a
thrust bearing is in order.
Dean
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