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Pneumatic retract question
My first foray into pneumatic retracts. I had a spool valve that would leak air under pressure, it would lose 80 psi in 5 - 10 min. It was from Black Horse, as the construction was nearly identical to the fixed gear from Seagull that came with the plane (82" AT-6). I bought a new one, a Robart, and it will lose air, but about 5 psi in an hour. I think that's good, but I haven't found anything to tell me what I should be looking for as far as what constitutes good or bad. Once I hook the lines to the retracts themselves, I know I will get more leakage, but what kind of loss over what time would be acceptable? Say I start with 100 psi in the tank, should I have maybe more than 50 psi left after an hour, or should I cycle the gear say, 4 times in the hour, and have 30 psi left?
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RE: Pneumatic retract question
Smear a dab of vaseline on each of the "T" fittings (and any other place where a hose connects) and see if that doesn't solve it
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RE: Pneumatic retract question
Ok, I could see where that would help seal any leaks at the barbs, but what about the retract cylinders themselves? The spool valve I replaced was leaking past the O rings in the valve, Hobby People replaced the valve, but the new one was only marginally better. I even went and put a piece of teflon tape under the O rings, it didn't help there.
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RE: Pneumatic retract question
Well, if the valves or cylinders are leaking, not much you can do (at least that I am aware of). I have found that most leaks are in the connections.
I wonder if a little lite oil in the cylinders would help (but I'm only guessing) This is why I hate pneumatic retracts! [:@] |
RE: Pneumatic retract question
Perhaps try Springairs, real ones not Robarts copies where there is only a dump valve.
John |
RE: Pneumatic retract question
I do not know what type of o-rings that Robart uses.
Why does that matter? Different types of o-rings will react with various lubricants. If using the wrong lube, your o-rings could swell and/or harden or crack; that goes for your tubing as well. It does not take long to ruin an o-ring. I have found through the years that silicon grease or food grade silicon spray are about the safest to use, except on silicon and natural rubber o-rings. Follow the link to a compatibilty chart by Marco Rubber http://www.marcorubber.com/compatibility.htm Pure silicon grease is available through a local Dive shop or on-line. Food grade spray is available through your local NAPA shop or on-line. |
RE: Pneumatic retract question
Mike, what is your prefered brand? Ihave a ASMP-61 that is waiting to be built, and a while back, I finally bought the stock retracts for it. They ended up going back and HPsaid the replacements had the same problem. This was a mechanical issue that left them setting like a chair with one short leg. Inever got to the actual operations of them
There is, or was one option for a motor driven system that operated just like a retract servo in that each retract plugged into a Y or splitter and everything was contained to the retreact and a servo lead. I"ve misplaced that companies name though. Also is there any build articles you know of for making such a retract.. Don ORIGINAL: MinnFlyer Well, if the valves or cylinders are leaking, not much you can do (at least that I am aware of). I have found that most leaks are in the connections. I wonder if a little lite oil in the cylinders would help (but I'm only guessing) This is why I hate pneumatic retracts! [:@] |
RE: Pneumatic retract question
1 Attachment(s)
http://www.horizonhobby.com/Products...ProdID=EFLG400
These were what I was going to get, but they were going to be on backorder for over a month. As long as I have been screwing around with these, I should have gone with them, I could be flying now. There is these guys now, too.... http://www.downandlocked.com/index.htm |
RE: Pneumatic retract question
I met Mitch Stott from Down & Locked at Joe Nall this year and I was so impressed with his product that I asked him if I could do a review for him.
D&L does not make retracts, they take YOUR existing retracts and convert them to electric by replacing the pneumatic cylinder with an electric one. It's really a great setup. They currently have the Robarts out of my Cessna 310 which I should be getting back any day now so I can finish up the review. |
RE: Pneumatic retract question
That's even better.. Any idea of prices? I couldn't find a hint on their web site.
Don |
RE: Pneumatic retract question
I think it varies a bit. You can shoot them an email and let them know what setup you have and I'm sure they will send you a quote
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RE: Pneumatic retract question
ORIGINAL: bingo field My first foray into pneumatic retracts. I had a spool valve that would leak air under pressure, it would lose 80 psi in 5 - 10 min. It was from Black Horse, as the construction was nearly identical to the fixed gear from Seagull that came with the plane (82'' AT-6). I bought a new one, a Robart, and it will lose air, but about 5 psi in an hour. I think that's good, but I haven't found anything to tell me what I should be looking for as far as what constitutes good or bad. Once I hook the lines to the retracts themselves, I know I will get more leakage, but what kind of loss over what time would be acceptable? Say I start with 100 psi in the tank, should I have maybe more than 50 psi left after an hour, or should I cycle the gear say, 4 times in the hour, and have 30 psi left? I top off the air tank on my planes every other flight. If the tank holds enough pressure to operate the retracts reliably after 30 minutes, I consider that "done". |
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