[PSUBS-MAILIST] Pneumatic Rotary Actuators

[Alan James]

Thanks Sean,
sounds a good idea, I will look in to it a bit more.
I'm not against hydraulics, but with a ready sauce of energy in compressed air, I will save space, 
complexity & limit noise by going with pneumatics over hydraulics. 
The sub is for recreational purposes to 500 ft.
Regards Alan


________________________________
 From: Sean T. Stevenson <cast55 at telus.net>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
Sent: Monday, April 7, 2014 1:41 PM
Subject: Re: [PSUBS-MAILIST] Pneumatic Rotary Actuators
 


I have built manipulators in the past using a small hydraulic motor to rotate the inner half of a hydraulic slip ring, (outer half, motor and arm structure all attached) with manipulator jaws attached that were actuated hydraulically through the slip ring.  Not sure why you're against hydraulics, but there's no reason you couldn't do the same thing with an electric stepper motor and pneumatic actuation.

Sean



On 2014-04-05 13:39, Alan James wrote:

Thanks Jim K & T,
>thats got me re-thinking things. I might be better to rotate via an electric
>motor inside the hull & hold with pneumatics outside. I've got an idea those
>rotary actuators are expensive.
>Alan 
>
>
>
>________________________________
> From: "JimToddPsub at aol.com" <JimToddPsub at aol.com>
>To: personal_submersibles at psubs.org 
>Sent: Sunday, April 6, 2014 2:43 AM
>Subject: Re: [PSUBS-MAILIST] Pneumatic Rotary Actuators
> 
>
>
> 
>Hi Alan,
>Could you use a sealed-unit worm gear operated by a small electric motor?  That would hold at 180 degrees or any other position you desire.
>Jim
> 
>In a message dated 4/5/2014 8:13:43 A.M. Central Daylight Time, kocpnt at tds.net writes:
> 
>>Hi Alan, 
>>
>>
>>If you use a thru hull, a linear actuator working at 12, 24 or 36 volts works well as well as giving more positive locations than air. They are simple and robust however slower than an air cylinder.
>>
>>
>>You can find some examples at www.surpluscenter.com
>>
>>
>>Best Regards,
>>
>>
>>
>>
>>Jim K
>>
>>
>>
>>On Fri, Apr 4, 2014 at 5:10 PM, hank pronk <hanker_20032000 at yahoo.ca> wrote:
>>
>>Alan, 
>>>you can rotate 180 degrees with a single air cylinder and a watts link.
>>>No need for an actuator
>>>Hank
>>>On Friday, April 4, 2014 4:04:18 PM, Alan James <alanlindsayjames at yahoo.com> wrote:
>>>
>>>Hi, 
>>>I'm wondering if anyone has had any experience with either pneumatic
>>>rack & pinion actuators, or rotary vane actuators, operating underwater.
>>>I need to rotate something through 180 degrees & have it held with a bit
>>>of clamping pressure at one end of the motion.
>>>One concern is seawater getting in to the gearing of those items, & there reliability. 
>>>Another option, could be a normal pneumatic cylinder with an external
>>>rack & pinion added. Am trying not to have to go to hydraulics.
>>>Alan
>>>


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