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"Spring Air Retracts" Won't Retract

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Old 08-08-2010, 04:55 PM
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flycatch
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Default "Spring Air Retracts" Won't Retract

I'm new to retracts and just finished installing a set of 700 series "Spring Air". The down lock mechanism releases but the gear will not retract. Air is getting to the cyclinders since they are spongy to the touch. They behave like there is not enough air pressure to extend the pistons. I'm using an electric air compressor to fill the air tank and the pressure gauge maxiumizes at 80 psi. I check for air leaks and found none. When I release air pressure to gear does lock due to being spring loaded. I'm using vendor structs that are overall in length 6.5" and a set of ROBART wheels 3.75" diameter. Can it be the weight of the strut wheel assembly or have I overlooked something obivous. I looking for some advice to resolve this issue.
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Old 08-08-2010, 11:03 PM
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Hi,
All air retracts, that Ive had, are designed to handle 100 psi, about 110 max. Spring Air, Robart and a knock off set.
80psi is only 80% of the force the pistons are capable of making.

With the Spring Airs the air pressure has to overcome the force of the springs too. Not just the weight of the strut and tire.

Having said that, its my guess that the pump isnt working very well for some reason. Like maybe its not efficient past a certian point and producing a true 80psi? IMO a true 80psi charge should cycle the gear once or twice at least.

Cheers,
James
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Old 08-08-2010, 11:16 PM
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flycatch
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Thanks, for the reply. I found the problem and now I can put 150 psi into the air tank. The air line attached to the compressor had a massive air leak. I didn't notice it due to the noise of the compressor. The "Spring Air" retracks require a minimum of 100 psi to operate correctly and with a full tank, 150 psi, I can get seven full cycles. Another problem surfaced after I solved the air leak. Another air leak sufaced in the control valve. I'm using a ROBART VCR valve and it has an air leak. After I discovered this leak I replaced the valve with another ROBART VCR and it leaked too. Both these valves are brand new and both leak air. Is this normal or are they both defective?
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Old 08-09-2010, 07:21 AM
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I would be decidely uncomfortable putting 150 psi into the tanks of my Springairs. 100 lbs works just fine for me on my Thirtyeights.

John
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Old 08-09-2010, 10:17 AM
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If your servo motion to the control valve is any more than what is absolutely necessary to operate the valve then you stand a good chance of the control valve leaking.
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Old 08-09-2010, 10:28 AM
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The valves' leak in the close position. I manually checked these vales to eliminate such a problem in the linkage set-up. Air is escaping around the barrel. This leads me to believe the internal seals are defective. I willing to bet there are two "O" rings, one at either end of the housing which the barrel slides through. This is a sealed assembly suppossedely, is it not? The valve supplied with the "Spring Air" retracts leaked also.
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Old 08-09-2010, 12:49 PM
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Let me try this one more time. The inside of the valve is indeed a stem with two O rings. When attached to a servo - if the servo moves any more than absolutely necessary there is a chance that the servo linkage is putting the stem on a "bind". It doesn't take much to cause one of the O rings to leak when your dealing in this type of pressure. You could test the valves by disconnecting the servo linkage and operating the valve by hand there by it would be a linear motion operating the valve and could not be putting any thing on a "Bind" no matter how small.
I'm not sure of what the range of motion required for Spring Air retracts but Rhom Air's only require approx 1/4" of motion - end to end.
Not trying to cause any problems here but it seems strange that two new valves would both leak in the same installation.
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Old 08-09-2010, 01:14 PM
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I tried the manual approach and the valves still leak. The travel amount is 1/4 inch as per the instructions. I also find this odd that all three valves leak air.
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Old 08-09-2010, 05:24 PM
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For all those who have provided information and advice I have found the cause of the second air leak. A "T" fitting was leaking air at the base of one of the barbs. This fitting was adjacent to and in close proxmity to the air valves that I thought were leaking. Thinking about this problem told me that the odds against all three valves leaking was not probable. I used the old technique of using saliva to locate the point of origion of this leak. I could hear it hissing but it was not until I applied this wetting agent did the problem reveal itself. Thanks againg.
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Old 08-09-2010, 05:28 PM
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Soapy water in a spray bottle is great for detecting air leaks in retract systems.
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Old 08-10-2010, 08:55 AM
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ORIGINAL: flycatch

For all those who have provided information and advice I have found the cause of the second air leak. A ''T'' fitting was leaking air at the base of one of the barbs. This fitting was adjacent to and in close proxmity to the air valves that I thought were leaking. Thinking about this problem told me that the odds against all three valves leaking was not probable. I used the old technique of using saliva to locate the point of origion of this leak. I could hear it hissing but it was not until I applied this wetting agent did the problem reveal itself. Thanks againg.
Glad to hear your getting the system sorted.
Every air leak Ive had has been due to poor quality plastic T's. I have a plane/system I set up about a year ago and everything was great initially. The system would hold pressure all day and was trouble free. Then a few months into use I had two T's just develope leaks for no appearent reason. At first the leaks were a minor nuisance, losing about 1-2psi over 20 minutes or so. But the leaks worsened and forced me to go looking for the prob.
All Im getting at, is that if later you discover a minor leak go after it. Odds are the leak will just get worse.
Just for future reference? Ive swapped out all the SA and Robart plastic T's I had for AirPower T's. So far, so good. 9 months now with no issues.
Cheers,
James
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