Air in loader system

[zrtext]

On my Case ih compact tractor I seem to have gotten air into the loader and bucket cylinders. The cylinders have slop in them and I can move the bucket 4" by hand. Causes problems when I back drag to level of material.
What's the best way to bleed out the air without a big mess? I think it might have ran low on fluid one time after I purchased a new backhoe. I bad I know.

 

[WinterDeere]

The usual method of bleeding is to crack the nut loose on the cylinder fitting on the side of the cylinder being compressed. But yeah, it makes a big mess.

Others just run the cylinders through many full cycles, hoping it eventually works all of the air back through the line, but I’ve never had much luck with this. Loader lines are very long, so it’s easy for air to get trapped out at the end of what is basically i
a dead end system.

 

[JimRB]

I have rebuilt hydraulic cylinders on my JD. I just work the cylinders both directions to purge the air.

 

[WinterDeere]

I have rebuilt hydraulic cylinders on my JD. I just work the cylinders both directions to purge the air.

I'd bet there's 35 feet of line between the tilt cylinder on my snow plow and the hydraulic reservoir on the tractor, because JD routes their 3rd function from the end of the loader arms to a solenoid and ports on the rear of the tractor, where it's then routed forward again to tie into the main loader hydraulic manifold.

I'd guess you could eventually work all the air from that little cylinder thru all of that line. But given the volume in the lines is many times greater than the volume of the cylinder, it's going to take an awful lot of cycles!

 

[RayIN]

I'd bet there's 35 feet of line between the tilt cylinder on my snow plow and the hydraulic reservoir on the tractor, because JD routes their 3rd function from the end of the loader arms to a solenoid and ports on the rear of the tractor, where it's then routed forward again to tie into the main loader hydraulic manifold.

I'd guess you could eventually work all the air from that little cylinder thru all of that line. But given the volume in the lines is many times greater than the volume of the cylinder, it's going to take an awful lot of cycles!

Wonder how workers on the assembly line accomplish the task? Time is money on an assembly line.

 

[TMGT]

I'd bet there's 35 feet of line between the tilt cylinder on my snow plow and the hydraulic reservoir on the tractor, because JD routes their 3rd function from the end of the loader arms to a solenoid and ports on the rear of the tractor, where it's then routed forward again to tie into the main loader hydraulic manifold.

I'd guess you could eventually work all the air from that little cylinder thru all of that line. But given the volume in the lines is many times greater than the volume of the cylinder, it's going to take an awful lot of cycles!

I've done it on my backhoe and loader after cylinder rebuilds, that's fairly large cylinders and a lot of line. Only takes a few cycles to remove the air.
It sounds like the op either has a problem thats introducing air into the system, or there are some seals going out, if its a persistent problem.



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[TMGT]

Wonder how workers on the assembly line accomplish the task? Time is money on an assembly line.

The system in that video has a small reservoir that can't handle the volume of fluid the cylinder requires, thats why it has to be done in stages.

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[RayIN]

The system in that video has a small reservoir that can't handle the volume of fluid the cylinder requires, thats why it has to be done in stages.

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That applies to the vast majority of hyd. systems. HWH builds closed hyd systems for RV's, they say it can take up to 3x to remove all air from a system that has been opened.

 

[TMGT]

That applies to the vast majority of hyd. systems. HWH builds closed hyd systems for RV's, they say it can take up to 3x to remove all air from a system that has been opened.

I wouldn't say majority, most systems used on equipment have extra capacity for cooling.
The only systems I've really seen with small reservoirs are limited use systems, like you might find in electric over hyd leveling jacks that maybe see a minute or two of cycle time for the day.

Tractors, construction equipment, log splitter etc. have enough capacity that you can fill the reservoir, and cycle empty cylinders and then just top off.



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[Bentrim]

As has been stated before work the cylinder thru a few cycles, that will work the air out of the cylinders. It may help if you can level the cylinder or raise each end as you cycle the cylinder so the air goes out of the cylinder first.
I used to work with farm equipment and installed a lot of new cylinders and loaders and found just cycling the cylinders a few times removed all the air, be sure to check the oil level in the resourvoir after bleeding.

 

[flyingace43]

On my Case ih compact tractor I seem to have gotten air into the loader and bucket cylinders. The cylinders have slop in them and I can move the bucket 4" by hand. Causes problems when I back drag to level of material.
What's the best way to bleed out the air without a big mess? I think it might have ran low on fluid one time after I purchased a new backhoe. I bad I know.

Had a case 45C and it did the same thing so I would raise the loader all the way up then cycle the bucket a few times and it would be ok until the next time I used it. Fixed by trading it in on a Yanmar YT347 and no longer have any problems now.

 

[RandyT]

The biggest issue with most of the compact tractors is the pump cannot produce enough volume to keep up with refilling the cyinder as the cylinders move under heavy loads when lowering or dumping the bucket. This causes a vacuum to form in the gravity side of the cylinder leading to cavitation of the fluid. This creates a low pressure issue and basically boils the fluid creating air pockets that then have to be purged to get the rigid hydraulic feel back Normally more common with dumping the bucket then raising or lowering the arms, but produces that floppy issue.

Restrictor valves are suppost to help prevent this and in some cases does, but are not totally effective especially for somebody that doesn't run at full throttle when using the loader.

 

[D&D]

On my Case ih compact tractor I seem to have gotten air into the loader and bucket cylinders. The cylinders have slop in them and I can move the bucket 4" by hand. Causes problems when I back drag to level of material.
What's the best way to bleed out the air without a big mess? I think it might have ran low on fluid one time after I purchased a new backhoe. I bad I know.

If you’ve cycled the cylinder(s) 6, 10, 12 times (w/e , pick a number) air is being introduced somewhere. Check tightness on all the hydraulic fittings and every o-ring seal (orfs, orb, q/d) becomes suspect. As an example,

https://www.hydraulicsdirect.com/_next/image?url=https%3A%2F%2Fapi.hydraulicsdirect.com%2Fimages%2Fdetailed%2F27%2FSS-6801-08-08_TopView_Rect.jpg&w=3840&q=75

 

[WinterDeere]

This creates a low pressure issue and basically boils the fluid creating air pockets that then have to be purged to get the rigid hydraulic feel back

Wow... I learned something, here! I can understand how this would happen, but not being a chemist, I'm wondering how the bubbles would persist once that side of the system regains pressure. No air is introduced, the bubbles would be at low pressure, and I would think they should disappear every bit as quickly as they appeared, immediately upon the restoration of pressure.

 

[RandyT]

Wow... I learned something, here! I can understand how this would happen, but not being a chemist, I'm wondering how the bubbles would persist once that side of the system regains pressure. No air is introduced, the bubbles would be at low pressure, and I would think they should disappear every bit as quickly as they appeared, immediately upon the restoration of pressure.

They do, but the second side of this is the side of the cylinder that was under vacuum becomes an open return to tank when the cylinder is actuated. So unless special valves are used, one side of the cylinder is always under system pressure and the other side is low pressure or neutral.

 

[zrtext]

If you’ve cycled the cylinder(s) 6, 10, 12 times (w/e , pick a number) air is being introduced somewhere. Check tightness on all the hydraulic fittings and every o-ring seal (orfs, orb, q/d) becomes suspect. As an example,

https://www.hydraulicsdirect.com/_next/image?url=https%3A%2F%2Fapi.hydraulicsdirect.com%2Fimages%2Fdetailed%2F27%2FSS-6801-08-08_TopView_Rect.jpg&w=3840&q=75

thank you as i will check into the fittings and hoses for issues

 

[zrtext]

They do, but the second side of this is the side of the cylinder that was under vacuum becomes an open return to tank when the cylinder is actuated. So unless special valves are used, one side of the cylinder is always under system pressure and the other side is low pressure or neutral.

yes I'm well aware of the of that, thank you

 

[D&D]

thank you as i will check into the fittings and hoses for issues

Being a bit of a Debbie downer now. I’d start with the suspected cylinders and valves. Unfortunately, it could be on any part of the tractor. Last one I had, it was under the seat on the 3 point fittings