[PSUBS-MAILIST] hydraulics

[hank pronk]

Vance,
I almost forgot,,, I have the entire drive unit rebuilt and painted for final assembly.  I figured out how the seal works .  It uses an 891 Chesterton mechanical seal (600psi) .  I will put it back together this weekend. I machined a cap that goes over the propeller shaft so I can pressure test the seal with the motor running.
Hank

From: Vance Bradley <Vbra676539 at AOL.com>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
Sent: Thursday, September 19, 2013 2:40:53 PM
Subject: Re: [PSUBS-MAILIST] hydraulics



I agree, bit wear. And tear can cause weeping and it will weep to the path of least resistance. Just something to keep on mind for those experimenting for the first time (or thereabouts).
Vance

Sent from my iPhone

On Sep 19, 2013, at 4:27 PM, hank pronk <hanker_20032000 at yahoo.ca> wrote:


Vance,
>Agreed, but there is a way to avoid this without compensation.  You must use cheap hydraulic cylinders because they use an o-ring on the shaft instead of a wiper seal.  A wiper seal needs pressure on one side to seal against water intrusion.  With an o-ring seal that is not the case, an o-ring is a non directional seal.  Essentially the hydraulic cylinder with an o-ring seal is exactly the same as a reach rod sealing system.  
>Hank
>
>
>From: "vbra676539 at aol.com" <vbra676539 at aol.com>
>To: personal_submersibles at psubs.org 
>Sent: Thursday, September 19, 2013 9:10:55 AM
>Subject: Re: [PSUBS-MAILIST] hydraulics
>
>
>
>Hank and all,
>The issue is overall system pressure versus ambient pressure. If you have a hydraulic unit that builds pressure only when it is activated, and returns to zero when static, then any, and I mean ANY leak point will allow water to creep into your oil. A spring loaded compensator preset to your max ambient plus a little would mitigate that by maintaining system pressure at whatever you set it for.
>Vance
>-----Original Message-----
>From: hank pronk <hanker_20032000 at yahoo.ca>
>To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
>Sent: Thu, Sep 19, 2013 3:22 am
>Subject: Re: [PSUBS-MAILIST] hydraulics
>
>
>H Alan,
>Bicycle brakes would probably work quite well because they are made from very good material.  
>Hank
>
>
>From: Alan <alanlindsayjames at yahoo.com>
>To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
>Sent: Wednesday, September 18, 2013 11:55:49 PM
>Subject: Re: [PSUBS-MAILIST] hydraulics
>
>
>Hi Brian,
>I've wondered about this also.
>I was looking at the hydraulic brakes they have on bicycles now days &
>wondering if you could adapt them for functions like releasing emergency
>bouys or similar.  The manual hydraulics they have on boats, like steering units
>are pretty expensive. Would be good to find something of suitable material
>off the shelf hat could be used.
>Alan
>.
>Sent from my iPad
>
>On 16/09/2013, at 5:28 AM, "brian" <brian at ojaivalleybeefarm.com> wrote:
>
>> I wonder if those human powered hydraulics could have an application for our boats, like the cats in the America's cup.
>> 
>> Brian
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