[PSUBS-MAILIST] thruster compensation

[Alan via Personal_Submersibles]

Cunning plan Hank.
So the cylinder is just really a bladder that keeps the motor
fluid at ambient pressure! 
If you fitted an extension spring on the external rod to give a 4 or 5 psi overpressure
you would have something akin to a commercial compensator!
Even better, fit a spring of the correct strength internally.
You could even fit a micro switch inside the cylinder to indicate low oil level, & maybe
water ingress, & have the wiring run out one of the ports!
I like this idea, will look in to it.
Alan



Sent from my iPad

> On 16/02/2017, at 10:32 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> I have just installed my two additional motors on Gamma that are mounted to the manipulator assembly borrowed from Elementary 3,000.  To compensate them I used a single air cylinder 1.5 in bore with 4 in stroke as the compensation bladder.  The cylinder is filled with light hydraulic oil and the motors are filled with WD40.  There are hydraulic hoses connecting the cylinder to the two motors.  I reversed one seal in each motor so the one seal keeps water out and one seal keeps oil in.  There is a tiny bit of air in the system but that makes no difference because the cylinder piston has enough travel to compress the air.  I think oil enters compensated motors because the oil spinning creates pressure from centrifugal force and the seals are oriented to keep water out.  The oil can then escape, that is why I have turned one seal around.  I will be testing in a month or so, and we will see, I guess.
> Hank
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