Can a Bleed Line Improve Air Removal in Hydraulic Circuits?

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prickerbush
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Hey all,

I never studied hydraulic circuits but I needed to design/make a hydraulic system for some research equipment. The system (in the attached schematic) has been hooked up and used for 6 months or so. However, I think we went the hard way on with getting the air out (we had no idea what we were doing.

Anyways, my question is can I put a bleed line on this system to help with getting the air out. Never mind if the symbols are drawn incorrectly as this is pretty much just a general schematic for what we have done. If it helps, the max pressure we will ever run in the system is about 2000 psi.

Thanks for the help!

-Marc
 
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A system should have a place where air naturally accumulates. If the cylinder is mounted vertically, that would be the place. Put the air bleed there. If in a simple system you have no such point, then don't worry about it. The air will wash back to tank and automatically purge itself from the system.
 
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The only way I have ever had to bleed a hydraulic injection moulding machine circuit is by cycling it. Over a few hundred cycles it does makes its way out. They all have an open tank as in your diagram.

Take care though - hydraulic oil compresses the air until stiction is suddenly overcome and then the cylinders jump - too far sometimes! That much air is usually gone after a dozen cycles or so and it behaves better after that.