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Re: [PSUBS-MAILIST] Hydraulic Drive Unit
Gary R. Boucher schrieb:
> Each design is an optimization of purpose based on a very extensive set of
> tradeoffs. The engineer's main purpose is to make judgements as to what is
> important and what is not, what is going to promote the design philosophy
> and what is not. Good engineers are going to weigh the merits and balance
> the pros and cons.
:-))
> I hear a lot of talk about propulsion on PSUBS. I hear some really
> outlandish proposals. Most are not feasible, but I seldom discard these
> ideas, in that I put many of them on the shelf for later consideration.
:-)))
> >Carsten Standfuss obviously understands the issues.
>
> Carsten apparently is a good engineer and builder. But, just because he
> elected to not use hydraulics for his controls does not make, in itself,
> hydraulic controls a poor decision.
Right..
May I should explain how the process on my sub was..
First step : I decided to have hydraulics for the Thruster and the vales
and the rudder
and all outside in the seawater direct on the rudders etc. The reason
was : the simple
hydraulic truehulls. And the compact force hydraulics have. And that I
get a big pump for free.
Second we found out :
That standard hydrauilc motors and cylinder are not seawater resistant
over longer periods
and if they failed we can not work on it in the water.. so boat has to
be back into the harbour
and than move onshore - just two times 1000 US Dollar for the crane.
Also the lip-bearing
of the cylinders and motors are normally designed for inside pressure
higher than outside..
- so we decided to put the cylinders inside.
Third we found out that the 2 x 9 KW Thruster need a big hydraulik oil
storage tank
for cooling reason and a bigger pump - the 30 % performance lost goes
mostly to head..
- so we decided to have electric thruster direct in the pipes -
drill-motor typ- means
standard electricmotors for deep-drill-holes - allready filled with
water or oil.
With all the hydraulics inside it was just a small step - just the
information that
strong DC servos available - to keep out the hydraulics complete..
I use hydraulic on the yard every day - there are many good reason for
hydraulic
and Euronaut will have a short hand power hydraulic double action
cylinder to open the
500 pound heavy diver exit hatch - because hydraulic means - hi force
and compact
on the place were the action is.
Just today we make a new concept for the machinery room concept for the
sub
- is number 11 or 12.. i think.. Without the hydraulic pump it is
nessesary
to re-think some other components there - maybe I can have a small
workbench there.
In my first days on Sgt.Peppers I have a lot of trouble with the
oil filled outside electric thrusters.. so I rebuild them to pressure
air compensation..
.. One day the storgae bottle had a bad conection the pressure air goes
away
and the motors flooded with water.. .. was freshwater - obviously it is
much
more difficult to flood a hydraulic cylinder or motor..
I personaly think that seawater resistant water-hydraulic can be a very
nice solution
- no big deal if you have small leaks.. and if seawater goes inside - it
will be
have only a very little effect to all the freshwater inside the system.
Seawater in
oil filled system can be a nightmare..
Be happy - Carsten
> Gary Boucher