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Old Jul 11, 2015, 05:52 PM
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Robart valve trouble

Is it just me? I've been having leak-down trouble with the last couple of valves. I even put a seal kit in one and lost air in 15 minutes.
Is it possible I am adjusting them down to where they are too soft (slow) and that is causing problems?
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Old Jul 11, 2015, 10:03 PM
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Hi, check your air cylinders first.
When the retract system go's up or down the waist air from the retract cylinders expels through the valve. When the retract system is not being used it looks like the valve is leaking but its just slowly draining from the cylinders.
I had the same problem but after scratching my head for a couple of days traced it back to the cylinders.
For me i always make my complete retract system removable to trace leaks underwater.
Also a detergent froth and a paint brush painted round connections is an old trick.
I wire on all connections and pump mine to 120 Pounds.
Dave.
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Old Jul 12, 2015, 07:21 AM
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I use a Windex spray bottle for in plane tests. It has enough soap to make bubbles if there is a leak. I think I made some progress. It seems I reduced leaks by opening up the needle screw settings. Maybe a problem with having them too low (slow)? Will try again today.
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Old Jul 12, 2015, 05:48 PM
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I have a pair of extension connections so I can do leak checks with the wings off and the fuse open. I use Robart air lines which are transparent. Put a few drops of light oil in the air system, pump it up to pressure and watch the oil move. It heads for the leak.
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Old Jul 12, 2015, 09:02 PM
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Quote:
Originally Posted by aghost View Post
I have a pair of extension connections so I can do leak checks with the wings off and the fuse open. I use Robart air lines which are transparent. Put a few drops of light oil in the air system, pump it up to pressure and watch the oil move. It heads for the leak.
Good idea
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Old Jul 13, 2015, 04:20 PM
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If you do the oil thing, it helps to cycle the gear a few times to distribute the oil throughout the system.
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Old Jul 13, 2015, 09:47 PM
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If the valve leaks after it has finished exhausting either the up or down air .
You can test with the bubbles, then the air bubbles can only come from one place and that is past the "O" rings in the retract cylinders.
Oiling may help.
On one of my aircraft where i needed maximum lift i ran the retract valve without the screws in.
Dave.
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Old Jul 14, 2015, 12:22 AM
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Quote:
Originally Posted by dave steffan View Post
If the valve leaks after it has finished exhausting either the up or down air .
You can test with the bubbles, then the air bubbles can only come from one place and that is past the "O" rings in the retract cylinders.
Oiling may help.
On one of my aircraft where i needed maximum lift i ran the retract valve without the screws in.
Dave.
Oh - didn't know you could do that?
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Old Jul 21, 2015, 01:32 PM
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i had a similar problem but mine would NOT leak on the ground. i even tested after overnight without leak, but the system lost air pressure in flight (AHHH!) trying to trace it down, i did note that it occurred after i slowed the gear movement to very slow. so i adjusted them to go a little faster. that seemed to cure it.
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Old Jul 21, 2015, 03:23 PM
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Well, I have two of these valves now that of gone to ****. One I put new seals in last week. At the time it held, now it's leaking out of both ends ???
My flying buddy is having similar troubles with one of his valves.
We bought rebuild kits. Installed them with no luck
I have ordered a different brand of valve.
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Old Jul 21, 2015, 04:15 PM
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well, at the risk of sounding like im insulting your experience, is your servo rod/arm pushing and pulling the actuator rod STRAIGHT in and out (no pressure sideways)? also, i read somewhere that you should (or was it should not?) go all the way to the stops (this may have been in the operating instructions for a different robart valve - green?).
.
i ordered a new one when i was having the problem, but haven't needed it. btw, the shaft on mine seems to have some minor scratches. not sure about that.
.
s what kind did you order?
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Old Jul 21, 2015, 04:43 PM
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Quote:
Originally Posted by pretendpilot View Post
well, at the risk of sounding like im insulting your experience, is your servo rod/arm pushing and pulling the actuator rod STRAIGHT in and out (no pressure sideways)? also, i read somewhere that you should (or was it should not?) go all the way to the stops (this may have been in the operating instructions for a different robart valve - green?).
.
i ordered a new one when i was having the problem, but haven't needed it. btw, the shaft on mine seems to have some minor scratches. not sure about that.
.
s what kind did you order?
That's okay. I believe there is nothing to be gained by going hard against the stops.
I went with this valve here. I read it has 4 seals vs 3 so maybe a better way to chamber it? I hope, it's working now.
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Old Jul 25, 2015, 07:02 PM
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Did you check the tank fitting itself? Robart seems to have a problem there.
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