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Problem with hydraulics and air


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#1 frenchy OFFLINE  

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Posted September 13, 2011 - 11:31 AM

So i've setup a secondary hydraulic system on my Dynamark 14/MF14 using a GM power steering pump driven off the main drive from the engine. I'm having a hell of a time getting the air out of the system. It seems like all the air is in the cylinder as I can pull and push the cylinder with no problem. How can i get the air out of the cylinder? The system is very basic, one pump, one 2-way control valve and one cylinder. Thoughts?

#2 ducky OFFLINE  

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Posted September 13, 2011 - 11:52 AM

I have ran into sutuations were the pump was sucking air in through the pump shaft. I have even seen a pump that was mounted to the engine timing cover and would over fill the hydraulic system with engine oil by sucking it in through the shaft seal.
I have something going on with my Dodge/Cummins steer brake pump aireating the oil. I am starting to think that is what is going on there.

#3 MH81 ONLINE  

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Posted September 13, 2011 - 07:11 PM

What kind of oil are you using? I'm wondering if you need to switch to something that foams less.

#4 olcowhand OFFLINE  

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Posted September 13, 2011 - 07:17 PM

Unless the pump is sucking air somewhere, multiple cycling of the cylinder should eventually purge the cylinder of the air.

#5 JDBrian OFFLINE  

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Posted September 13, 2011 - 07:26 PM

I've seen it before where a bad seal in the system would suck in air. Once it was on a Destroyer helicopter pulldown system. The thing would oscillate and they were blaming the control system. Turned out to be a bad seal pulling in air. Does your reservoir have an air space and is it vented?

#6 frenchy OFFLINE  

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Posted September 14, 2011 - 10:06 AM

I'm using ATF fluid and it is a vented reservoir. I need to get back on this project as i've been busy. Thanks for the help everyone. I'll repost when I try a few more things.

#7 frenchy OFFLINE  

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Posted September 16, 2011 - 11:47 AM

Update: cracked the pump housing while tightening the nipple. I'll repost when I have the new pump installed... :(




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