Bleeding lines on new grapple install

[RKJeepXJ]

Everyone says the hydraulic system is self bleeding. I find that hard to believe. If I start out with lines run from my rear remotes to the front for my grapple, the fluid won't travel all the way up to the cylinder before it runs out of travel. If I cycle it a few times, yea it would eventually mix and a good amount of air would get pushed back on the return stroke. I just don't see this really bleeding it out well.

One thought I have is since I have male and female couplings up front, I could simply hook them together and actuate the valve and essentially bleed the loop. Then to only air introduced would be from the grapple hoses and cylinder. Seems better than nothing. Thoughts?

 

[Winmac]

You are correct, some circuits will not never purge themselves of all air and require manual bleeding. Hooking the lines into a loop is a ideal way to clear most of the air.

 

[Wa11banger]

I had the same question a while back and got many of the same responses but was also unsure and do not know the answer. But, I will have more info for you this weekend if my parts arrive. I have a completely dry hydraulics system on a backhoe and as you know many many circuits to clear of air.. So after thinking about it I have broken the system down into recirculatory section and the fill and bleed section..

The recirculatory system is the reservoir, pump, and valve gang/block this should self bleed.

However the circuits beyond the valve block just moves fluid a distance forward and a distance back.. so here is what I think the possibilities are with that
The pressure will compress the air and get a large amount of fluid into the cylinders and eventually the air will work its way back but only through repetitive cycling over a long period of time.

Or

The air molecules are smaller than the hydro molecules and the can be "pushed" past the seals in the cylinders and this is how it is self bleeding.

Or

Like you suggest they will either have to be manually bled each cycle at each cylinder or looped to force each circuit to recirculate itself. Hopefully it will be an enlightening adventure for all of us

 

[kennyd]

Or

The air molecules are smaller than the hydro molecules and the can be "pushed" past the seals in the cylinders and this is how it is self bleeding.

Bingo.

 

[kennyd]

Everyone says the hydraulic system is self bleeding. I find that hard to believe. If I start out with lines run from my rear remotes to the front for my grapple, the fluid won't travel all the way up to the cylinder before it runs out of travel. If I cycle it a few times, yea it would eventually mix and a good amount of air would get pushed back on the return stroke. I just don't see this really bleeding it out well.

One thought I have is since I have male and female couplings up front, I could simply hook them together and actuate the valve and essentially bleed the loop. Then to only air introduced would be from the grapple hoses and cylinder. Seems better than nothing. Thoughts?

If that makes you sleep better, go for it.

 

[Tx Jim]

Back in the 60'-late 80's while employed at a JD dealership all the FEL's and other farm equipment that I assembled the hydraulic components self bleed and I believe that will do the same today. One can get enough oil on ones clothes working around farm machinery without attempting unnecessarily to bleed the air out

 

[Wa11banger]

Hah hey kennyd. Thanks for the reply.. btw I have pushed those hooks and shackle mount well past what I should be doing with them and they are still straight and strong. Thanks for the great product.

TxJim I was worried about that as much as anything. I didnt want to be spilling anymore hydro than I had to

RK, sorry for the highjack but at least its an on topic highjacking

 

[k0ua]

Back in the 60'-late 80's while employed at a JD dealership all the FEL's and other farm equipment that I assembled the hydraulic components self bleed and I believe that will do the same today. One can get enough oil on ones clothes working around farm machinery without attempting unnecessarily to bleed the air out

All I can say is that after hooking up my dry hoses from the rear remote, and into the grapple cylinder, all the spongyness (is that a word?) seemed to go away in about 10 cycles of the grapple. Maybe took a minute. No bleeding necessary.

 

[SpudHauler]

Hydraulic cylinders have seals that are oil tight not air tight.

Crack the fittings at each cylinder connection and move the lever until each leaks a small amount, re-tighten and do all the rest the same.

Cycle cylinder a few times, job done.

 

[kennyd]

Hah hey kennyd. Thanks for the reply.. btw I have pushed those hooks and shackle mount well past what I should be doing with them and they are still straight and strong. Thanks for the great product.

Thanks for the compliments Rick :drink: I'm glad your happy with the products.

 

[wdchyd]

Hydraulic cylinders have seals that are oil tight not air tight.........

???.....:confused3:

 

[/pine]

???.....:confused3:

Actually I don't think it (air) needs to get down to molecular in size to pass by a seal (that holds oil)...
Air can be compressed and doing so makes it (air(bubbles)) much smaller...

...most hydraulic cylinders will work with air the same as fluid under a NO-load scenario...

 

[Wa11banger]

Wdchyd, yessir we have many filters in our lives that separate differing liquids due to their molecule size. Now filters are not seals but I would assume the same principle applies to all things with a specific tolerance.

 

[wdchyd]

Wdchyd, yessir we have many filters in our lives that separate differing liquids due to their molecule size. Now filters are not seals but I would assume the same principle applies to all things with a specific tolerance.

Then why are hyd cylinders and air cylinders manufactured with the same kind of seal materials (buna, polyurethane, Teflon).......we are talking tractor hydraulics right?......or space shuttles

 

[aczlan]

Then why are hyd cylinders and air cylinders manufactured with the same kind of seal materials (buna, polyurethane, Teflon).......we are talking tractor hydraulics right?......or space shuttles

Air cylinders don't generally see 2000-3000 PSI, Parker lists 250PSI as the max pressure for their air cylinders: http://www.parker.com/literature/Industrial Cylinder/cylinder/cat/english/0106c002.pdf.

Aaron Z

 

[J_J]

Hyd cyl should be both liquid and air tight.

If not, then we would be bleeding a lot of air.

If a hyd cyl was not air tight, we could just push all the air out through the seals.

If you can push air past the seals of a cyl, the you can also push fluid out.

 

[Wa11banger]

Actually I work for NASA so I kinda was talking space shuttles! But in all seriousness I see your point. The scale of tolerance in our tractor hydraulics may not be to the exacting tolerances required in the aerospace industry.

JJ it is feasible that air can leak past our seals more easily than hydro fluid as these are not perfect seals. Matter of fact a little oil leaks out of the cylinder every time it is cycled. Just at the microscopic level

 

[wdchyd]

Actually I work for NASA so I kinda was talking space shuttles! But in all seriousness I see your point. The scale of tolerance in our tractor hydraulics may not be to the exacting tolerances required in the aerospace industry.

I figured that anyone from Huntsville works there

 

[Little Tractor Ferndale]

I installed a anbo grapple on my TC30 also a WR Long 3 function Aux. valve and did not bleed in any other way then running the circuit in one direction. The air in fact does bypass all on its own!

 

[Mike476]

Todays hyd systems that are self bleeding have check valves in the system that allow air to breathe out, usually in the actuating cylinders themselves. Aircraft hydraulic systems do the same; they also maintain a pressure in the header tank to ensure positive flow.

Hyd fluids are chosen because of their compression ratios and resistance to foaming, it is essential that air be bled from a system to prevent that from happening.

While the system will bleed itself I would probably look to loop the new lines as well, if for no other reason than to make sure I maintain a good level of fluid in the system.