[PSUBS-MAILIST] magnetic linear actuator

[Alan via Personal_Submersibles]

Hank,
you mean like a solenoid with a long stroke?
I have been designing a solenoid operated ballast valve but haven't got
round to working out how many turns of wire, how much force I need &
how many amps it will draw. 
A lot of solenoids have a short duty cycle, as they heat up pretty quick.
I would imagine this could be a problem if you wanted to hold something
in position for a long time.
Alan


Sent from my iPad

> On 30/09/2017, at 10:32 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan,
> I have not taken one apart yet but it sounds like it is a tricky one.  I was hoping there was some sort of magnetic rail actuator.  I have been Googling around but have not found anything yet.  I have had superb results with electro magnets under water (fresh)  and figure that could be the answer.  I  will keep looking.
> Hank
> 
> On Friday, September 29, 2017, 8:07:33 PM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Hank,
> I spent a lot of time investigating oil compensation of linear actuators along
> with Frank.. He was looking at the Lenco trim tab actuators.
> Have several. The motors in them are small & brushed & run rough in
> oil. When the rod extends that leaves a void inside the actuator that needs
> to be filled. So you end up with an external oil reservoir to fill the actuator
> with ambient pressure oil as it extends. ( so why not just push it out with the oil)
> There are micro switches that I drilled with tiny holes, to let ambient pressure
> in so they didn't trigger under pressure. Also there are electronics in some
> actuators that may be effected by pressure. And of course there is the wiring
> going in to the actuator that needs sealing & the seals on the rod that may need replacing.
> Much simpler to use hydraulics. I did see an electric manipulator operating
> at the Underwater Intervention Convention. Can't recall it's name.
>    From time to time I have a google on robot sites to see what is new. Or
> Alibaba to see if the Chinese have come up with anything cheap.
> Nearly bought a kids hydraulic arm toy that you assemble, with view to 
> scaling up out of aluminium.
> Keep thinking, but the robotics World is big & if there is a new & easier way
> of doing it they'll find it.
> Alan
> 
> 
> Sent from my iPad
> 
>> On 30/09/2017, at 1:08 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> I have been brain storming looking for a less expensive and less complicated means of building manipulators.  The obvious choice would be electric liner actuators, oil filled etc.  Then I was thinking about a magnetic actuator like a mag lev rail.  Is there such a thing?  You know, add more voltage and the actuator moves out further.  Any ideas?  
>> Hank
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