Pneumatic retract question
08-23-2010, 06:26 AM
#1
Thread Starter
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?
08-23-2010, 07:41 AM
#3
Thread Starter
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.
08-23-2010, 07:53 AM
#4
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! [:@]
I wonder if a little lite oil in the cylinders would help (but I'm only guessing)
This is why I hate pneumatic retracts! [:@]
08-23-2010, 12:10 PM
#6
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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.
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.
08-23-2010, 02:58 PM
#7
Senior Member
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
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! [:@]
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! [:@]
08-23-2010, 03:08 PM
#8
Thread Starter
RE: Pneumatic retract question
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
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
08-24-2010, 10:49 AM
#9
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.
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.
08-24-2010, 12:47 PM
#12
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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?
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".
