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Old Feb 02, 2013, 10:32 PM
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mx_ata2d's Avatar
United States, CA, Simi Valley
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Help!
robart retracts kickin my butt

OK, could really use some help. I bought a used Top Flite Cessna 310 with Robart retracts. I can not for the life of me get these things to work. The main valve leaked so I replaced it. Still no go. So I figured there had to be a blockage somewhere in the lines. No problem, I replaced all the lines including the T's. Still no go. There are no leaks anywhere and the can easily pumps up to 90+ lbs. Occasionally they will cycle either up or down, but not up and then down. I tried reversing the in and out lines at the valve this also didn't work. All 3 cylinders couldn't have gone at the same time could they? Am I missing something? Help please!
MX
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Old Feb 03, 2013, 09:18 AM
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The volume of air needed is probable more than you anticipated, and the pressure drops with the first movement, and had not enough pressure to continue the next. Get a pressure guage of some sort, and check that. Seems like I was running more than 100 psi on mine.

Les
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Old Feb 03, 2013, 10:51 AM
Zor
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Justification

Hi guys,

I will follow this thread to see if you find a reason for this problem.

I decided that I will use an electric system for the retracts on my PA 30 design. This thread sure seem to give me justificaton for my decision.

Thanks.

Zor
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Last edited by Zor; Feb 03, 2013 at 12:26 PM. Reason: Corrected "dccision" to "decision".
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Old Feb 03, 2013, 11:30 AM
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United States, WA, Port Angeles
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another quality add-on by zor!

ok on too something more constructive! start by making shure that each retract is clean and moves freely! if there an older set, they might need a good cleaning!

as noted above, my century jets I have on my mustang, start at 120psi, and start falling off at around 80psi.

when you are shure that they are clean and free of any obstruction, and they are still not working properly, then you will need to remove them one at a time, and check that they where mounted properly! if a retract isn't mounted properly, then it will bind!
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Old Feb 03, 2013, 11:50 AM
builder and crasher
United States, FL, Sebring
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Is it the Robarts Valve? It has speed controls on it, maybe they are closed? Can you disconnect the lines from the valve and actuate it to see if the air shifts from 1set of fittings to the other? Can you attach the pump directly to the retract to manually extend or retract it? Does the servo fully actuate the valve in both directions?
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Old Feb 03, 2013, 12:21 PM
Zor
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Quote:
Originally Posted by whiskykid View Post

another quality add-on by zor!

ok on too something more constructive! start by making shure that each retract is clean and moves freely! if there an older set, they might need a good cleaning!

as noted above, my century jets I have on my mustang, start at 120psi, and start falling off at around 80psi.

when you are shure that they are clean and free of any obstruction, and they are still not working properly, then you will need to remove them one at a time, and check that they where mounted properly! if a retract isn't mounted properly, then it will bind!
whiskykid

I am glad and appreciate that you have something more constructive.
I give credit to mx_ata2d for assuring that the units are not all full of dirt or sticky stuff and are free to move as expected.

mx_ata2d stated that there is no leaks but did not explain how he knows that. The symptoms seem to be that he has a lost of pressure (leak) within a single actuation.

Any obstruction (mechanical) would not be cause for any pressure drop. Any improper mounting causing a bind again would not cause any operation failure. If it binds either going up or down then a reversal would still work.

Any further comments whiskykid ?

Zor
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Last edited by Zor; Feb 03, 2013 at 01:06 PM. Reason: typo
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Old Feb 03, 2013, 01:30 PM
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I just thought about this, since it seems that all 3 are acting the same way, it is possilble that they are on the dry side!

robart says"Use white lithium or silicone grease only. Using other oils or types of grease will destroy the “o”-rings in the air system and void the warranty. There are only 2 components of the Air System that will need further lubrication: 1. retract mechanism air cylinder “o”-rings, and 2. air control valve “o”-rings"

oh and yes, robart say's "that there retracts operate from 90 to 120 PSI!" so at 90 psi you will probably only get movement in one direction!
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Old Feb 03, 2013, 01:36 PM
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I've pumped the retracts up with a robart pump that has a pressure valve, but at this point only only to about 80 or 90lbs. I left the pressure valve connected over night with zero drop. Everything does move freely. I will try pumping them up to advised 120lbs and let you know the results. I very much appreciate all your help. Stay tuned.
MX
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Old Feb 03, 2013, 01:50 PM
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thats great ta hear about them holding air!

just keep your finners away from them at 120psi, they will be moving in a hurry!

I tried to regulate mine with a wheel coller, still not happy with that set-up!
should break down and get a needle valve I guess!

I am jelous, I have always like the 310! very sexy airplane!
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Old Feb 03, 2013, 06:48 PM
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OK, so I pumped everything up to 120. While filling the tank the gear retracted. The two wing wheels locked in the up position but the nose gear didn't lock. It went up, but I was able to pull it back to the down position. The valve had zero effect in opening or closing. They only went up while pumping air to the tank. Can one bad cylinder cause the valve to not work? Cause them not to work at all?
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Old Feb 04, 2013, 08:23 AM
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depending on how you have them plumbed, yes a cylinder that has blow by, will pressurize in the oposite direction!

not knowing how old those retracts are, you could get a rebuild kit from robart, for like less the 20 bucks I think!

or try lubing them! I would start with the nose gear by the sounds of it!
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Old Feb 05, 2013, 05:41 AM
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Check for a pinched line.
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Old Feb 05, 2013, 09:12 AM
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I just remembered a problem that I had once. The air system was drum tight at both ENDS of travel, but leaked like a sieve once the piston got off the end, i.e., during travel.

Les
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Old Feb 05, 2013, 08:43 PM
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Quote:
Originally Posted by LesUyeda View Post
I just remembered a problem that I had once. The air system was drum tight at both ENDS of travel, but leaked like a sieve once the piston got off the end, i.e., during travel.

Les
I'm beginning to think this May be the problem. I think the problem is with the hnose gear. I've ordered a new cylinder from robart. I'll take it from there.
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