[PSUBS-MAILIST] Brushless Thrusters
Sean T. Stevenson via Personal_Submersibles
personal_submersibles at psubs.org
Sun Sep 7 20:02:33 EDT 2014
The Parker O-ring Handbook includes design guidelines for such dynamic shaft seals, including maximum surface speeds and so forth. I have used this on several occasions to design rotary shaft seals.
Sean
On September 7, 2014 5:21:33 PM MDT, Vance Bradley via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>Low rpm was the key. Much faster and the rubber overheats.
>Vance
>
>Sent from my iPhone
>
>> On Sep 7, 2014, at 7:04 PM, hank pronk via Personal_Submersibles
><personal_submersibles at psubs.org> wrote:
>>
>> Vance,
>> Sounds like a good option if you have in house machining. The
>cartridge seal shaft is equally fussy, it took me a few try's to get it
>perfect. I am sure Brian is a better machinist than I am, so should be
>no problem.
>> I believe the slower the rpm the better with o-ring seals.
>> Hank
>> --------------------------------------------
>> On Sun, 9/7/14, via Personal_Submersibles
><personal_submersibles at psubs.org> wrote:
>>
>> Subject: Re: [PSUBS-MAILIST] Brushless Thrusters
>> To: personal_submersibles at psubs.org
>> Received: Sunday, September 7, 2014, 6:49 PM
>>
>> Hank,
>>
>>
>>
>>
>> Harbor Branch used o-rings on the reduced output 1
>> 1/4 thrusters on the JSLs. The mid-body on the hard can
>> (actually the back 25% or so of the cylinder section) was
>> machined on the output side for planetary gears, and
>> machined on the motor side to replace the entire output
>> plate/bearing case for the motor itself (like a golf cart
>> motor bolts into a differential). Pretty nice and compact
>> for the day.
>>
>>
>>
>>
>>
>> The rear section of the hard can behind the gear
>> case is a hollow sand casting shaped like the long end of an
>> egg, webbed internally to support a 1" shaft, double
>> bearings, with double thrust bearings, and a tapered,
>> polished, hardened aluminum sleeve pressed in from the
>> pressure side.
>>
>>
>>
>>
>>
>> The shaft itself was machined to carry double
>> o-rings in square cross section grooves and terminated on
>> the internal end with a flex-coupling which mated
>> (obviously) to the output of the planetary output. A big
>> shaft was necessary to keep the jitters down to more or less
>> zero. Everything needs to stay exactly centered, as the
>> O-rings will go to pot a whole lot faster if there is any
>> flex or vibration at all in that prop shaft
>> shaft.
>>
>>
>>
>>
>>
>> Lots of development to get it right, finally, but
>> the props turned about 275-300 rpm (I don't remember
>> exactly, but something like that). 14" X 14" Kort
>> style prop in a machined syntactic foam nozzle supported on
>> a 4-legged frame welded to the aft part of the shell. I
>> actually have a blueprint of it, somewhere around here. For
>> those interested, the tip clearance between blade end and
>> nozzle sleeve was about 50-thousandths. NOTE: That would be
>> of an inch, Emile.
>>
>>
>>
>>
>>
>> There were no speed controls on the boats.
>> Fwd-Off-Rev only. You just turned thrusters on or off to
>> vary the push. When I was there, we had 5 for forward and
>> reverse (3 in a row on the centerline with 1 each to port
>> and starboard aft) plus a vertical and horizontal pair
>> forward and aft for steering and fine maneuvering (fine
>> maneuvering my ass!!!). That's right. NINE thrusters
>> that probably with cabling weighed over half a ton. Plus two
>> or three spares in the kit ready to bolt up at a
>> moment's notice as replacements. We were definitely in
>> the motor business with those babies.
>>
>>
>>
>>
>>
>> They were home grown but worked reasonably well,
>> although they were a little noisy with the gear case and
>> whatnot. That said, I never saw the electrical side flooded
>> on one of those things. Not once. Ever. We had a routine
>> service schedule and changed a thruster every so many hours
>> of service. Just put a fresh one on (two people could do a
>> change-out in about three minutes), then tear the
>> to-be-serviced unit down to check brushes and bearing lube
>> and change the shaft o-rings (which would be looking a
>> little fuzzy by then, but still worked fine--and even if
>> they looked brand new, we changed them). It needs a really,
>> really first rate waterproof lubricant, as the internal
>> shaft o-ring runs hotter than the one in contact with the
>> water, and was often in worse shape than the one primary as
>> a result.
>>
>>
>>
>>
>>
>> Once the JSLs re-certified to 3000 feet,
>> engineering redesigned the seals for better service, using a
>> ceramic cartridge seal in place of the o-rings, but that was
>> after my day. I'd hate to even think what
>> one would cost today, built commercially. You wouldn't
>> use them, probably, as a unit with twice that power is
>> probably a third the size and weight.
>>
>>
>>
>>
>>
>> Those thrusters on the Tritons,
>> for instance, look positively tiny by comparison, and
>> they're rated at over 2 hp. Then there's our own
>> Uncle Dr. Phil's new mag coupled ones. Now there's a
>> Christmas present to ask Santa for.
>>
>>
>>
>>
>>
>> All that aside, the o-rings will
>> work if you plan regular service (ie, scheduled o-ring
>> replacement) and don't wait for water intrusion. They
>> have to be done right during construction, though. Those
>> surfaces have to be mirror smooth.
>>
>>
>>
>>
>>
>> Vance
>>
>>
>>
>>
>>
>>
>> -----Original
>> Message-----
>>
>> From: hank pronk via Personal_Submersibles
>> <personal_submersibles at psubs.org>
>>
>> To: Personal Submersibles General Discussion
>> <personal_submersibles at psubs.org>
>>
>> Sent: Sun, Sep 7, 2014 4:51 pm
>>
>> Subject: Re: [PSUBS-MAILIST] Brushless Thrusters
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Brian,
>> Vance would know better than me, but I think if you keep the
>> rpm under 1,000 you
>> can use an o ring for a seal. I thought Perry did that in
>> the early subs to
>> 1,000 feet.
>> Hank--------------------------------------------
>> On Sun, 9/7/14, hank pronk via Personal_Submersibles
><personal_submersibles at psubs.org>
>>
>> wrote:
>>
>> Subject: Re: [PSUBS-MAILIST] Brushless Thrusters
>> To: "Personal Submersibles General Discussion"
>> <personal_submersibles at psubs.org>
>> Received: Sunday, September 7, 2014, 4:42 PM
>>
>>
>> Brian,
>> You can use a simple
>> mechanical seal, that is what the K subs have. An 891
>> Chesterton mechanical seal is good fo 600 psi, that is what
>> Gamma had when I got it. You can buy them on ebay for 100
>> bucks. Build the shaft to fit the seal, and your
>> sailing.
>> Hank--------------------------------------------
>> On Sun, 9/7/14, Brian Cox via
>> Personal_Submersibles <personal_submersibles at psubs.org>
>> wrote:
>>
>> Subject: Re:
>> [PSUBS-MAILIST] Brushless Thrusters
>> To:
>> "Personal Submersibles General Discussion"
><personal_submersibles at psubs.org>
>> Received: Sunday, September 7, 2014, 4:29
>> PM
>>
>> I
>>
>> talked to a hydraulics guy a few days ago about making a
>> seal for my motor pod. I told him I had a
>> high pressure
>> tank that I wanted to turn a
>> shaft inside the tank to stir
>> the contents
>> at 250 psi, ( didn't want his eyes to
>>
>> glaze over if I mentioned submarine !) Anyway he
>> directed
>> me to a system using a bronze
>> fitting that would tighten
>> down these rings
>> he called "cheverons" they are
>>
>> mating rings of a very high durometer . the bronze is
>> for
>> mating with stainless . I would have
>> to machine an
>> assembly for this , but once
>> I have my shaft size (1 inch
>> most likely) I
>> will be able to size everything
>>
>> accordingly. Brian
>>
>>
>> ---
>> personal_submersibles at psubs.org
>> wrote:
>>
>> From: hank pronk
>> via Personal_Submersibles
>> <personal_submersibles at psubs.org>
>> To:
>> personal_submersibles at psubs.org
>> Subject: Re:
>> [PSUBS-MAILIST]
>> Brushless Thrusters
>> Date:
>>
>> Sun, 7 Sep 2014 07:07:20 -0700
>>
>> Alan
>> When I upgraded the
>> cartridge seal in Gamma, I needed a pretty
>> Beafy thrust
>> bearing, it was no problem to
>> get. have since changer to
>>
>> Magnetic. I think you could replace the bushing
>> in a
>> thruster with a ball bearing and never
>> look back.
>> Hank
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> From:
>>
>>
>>
>> Alan via Personal_Submersibles
>> <personal_submersibles at psubs.org>;
>>
>>
>>
>>
>>
>>
>> To:
>>
>>
>>
>> Personal Submersibles General
>>
>> Discussion <personal_submersibles at psubs.org>;
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Subject:
>>
>>
>>
>> Re: [PSUBS-MAILIST] Brushless
>> Thrusters
>>
>>
>>
>>
>>
>> Sent:
>>
>>
>>
>> Sun, Sep 7, 2014 1:43:49 PM
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Hi Hank,the kort
>>
>> nozzle on the Indonesian thruster looks a bit
>> Naff. ( I am designing an art work
>> here.)I could get a price for the unit
>> without
>> kort nozzle, butI'm wondering
>> if I could
>> build something for 1/2 that
>> price.There are some
>> reasonably priced
>> brushless motors about.I
>> don't know
>> that I could just retro fit a thrust bearing
>> inside the can of the motor.I tried to put
>> a
>> thrust bearing for reverse inside my
>> brushed thrusters,
>> butcouldn't find one
>> with a thin enough
>> section to fit.Also the
>> motors are a bit
>> expensive to just buy
>> & hope you can fit
>> one.How did you fit
>> the thrust bearing on Gamma?
>> Did the
>> propellor shaft extend out the backof
>> the
>> motor?Alan
>>
>> Sent from my
>> iPad
>> On 7/09/2014, at 7:22 pm, hank pronk
>> via
>> Personal_Submersibles <personal_submersibles at psubs.org>
>> wrote:
>>
>>
>> Allan
>> Dont
>> worry about
>> thrust bearings to much. They are aesy to get,
>> I bought one for Gamma , real heavy duty for
>> 80 dollars.
>> Personally I would just use a
>> good quality bearing and
>> replace it once a
>> year for 8 bucks, if it is a small
>>
>> thruster. Are you not happy with the
>> Indonesia thrusters?
>> Or to pricey?
>> Hank
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> From:
>>
>>
>>
>> Alan via
>> Personal_Submersibles
>> <personal_submersibles at psubs.org>;
>>
>>
>>
>>
>>
>>
>>
>>
>> To:
>>
>>
>>
>> Personal Submersibles
>> General
>> Discussion <personal_submersibles at psubs.org>;
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Subject:
>>
>>
>>
>> [PSUBS-MAILIST] Brushless
>> Thrusters
>>
>>
>>
>>
>>
>> Sent:
>>
>>
>>
>> Sun, Sep 7, 2014 11:58:56 AM
>>
>>
>>
>>
>>
>>
>>
>>
>> Hi people,
>> I've
>> spent several hours today looking at brushless
>> thrusters
>> & wonder if anyone else has
>> looked at them or got any
>> ideas. There is
>> the Indonesian thruster I posted a few weeks
>> back at US 2,200. There is also the Haswing
>> Protruar 2hp
>> that Emile has; however they
>> state that it's for fresh
>> water only,
>> & I think Emile said it was a bit noisy.
>> The inrunner motors that have the winding
>> on
>> the outside, seem a good option as they
>> cool through
>> convection to the can. They
>> also need higher revs for torque
>> &
>> require a planetary gear box or similar. ( which a lot
>> have built in)
>> I was
>> looking at the
>> option of making my own
>> thruster, however the motor would
>> require a
>> thrust bearing & I don't
>> know of
>> any that would have one other than
>> maybe
>> a high powered battery operated drill.
>> Any
>> thoughts, suggestions thanks.
>> Alan
>>
>> Sent from
>>
>> my
>> iPad
>>
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