air lock? How do I bleed hydraulics?

[canucklehead]

I have a 1962 IH B414. I just had the rod replaced in my power steering cylinder, plus seals. So I hooked it all back up and it's not working. I manually moved the control valve back & forth on the steering cylinder (with tractor at idle), and it didn't move. I also noticed that the left of my 2 cylinders for rolling the bucket didn't move either (no bucket on right now, so it was easy to see). I'm guessing (hoping?) I only have an air lock. I never bled anything and thought it would just bleed itself, but a few hydraulic guys told me I might have an airlock.

So how do I bleed this? Where do i start?

Thanks.

 

[beenthere]

Might loosen a fitting to let the air out (if that is really the problem).

 

[AKKAMAAN]

I have a 1962 IH B414. I just had the rod replaced in my power steering cylinder, plus seals. So I hooked it all back up and it's not working. I manually moved the control valve back & forth on the steering cylinder (with tractor at idle), and it didn't move. I also noticed that the left of my 2 cylinders for rolling the bucket didn't move either (no bucket on right now, so it was easy to see). I'm guessing (hoping?) I only have an air lock. I never bled anything and thought it would just bleed itself, but a few hydraulic guys told me I might have an airlock.

So how do I bleed this? Where do i start?

Thanks.

It is not an air issue, no bleeding necessary.
You have a problem to get oil flow from pump to cylinder....

 

[J_J]

Is your 3pt working? That will tell you if you have flow and pressure. Air will normally purge after several attempts. Most cyl have the ports near the ends of the cyl, and would be hard to air lock. If you level the cyl and open the fittings, you might be able to bleed any air trapped. Have you actually gone through 5 to 10 cycles of cyl operation?

 

[canucklehead]

this thing has always had leakage issues and I would just top it up. it was really low when we replaced the cylinder. We drove tractor from the barn to the shop when it was really low, maybe even almost empty. THEN i filled the resevoir.

we haven't cycled it alot, since filling it up. so how long do I run it and cycle it to get the air out?

the PS was working before all of this, BUT the rod broke, thus reason for replacing it.

 

[J_J]

If your pump is good, and you have cycled the cylinders a good number of times, with no good results, then a gage is necessary to see if there is flow and pressure. Maybe your PS is taking all the fluid. Does your PS go lock to lock with power?

 

[canucklehead]

i haven't really cycled the cylinders. I'll try that. there was probably a lot of air in there. The pump is relatively new and should be good.

 

[Soundguy]

can always remove the pressure line and aiminto the sump and hit it till oil comes out.. install it to a compressed cyl, then do the same onthe others.. then work it back and forth.. then refill the sump.. etc..

 

[canucklehead]

how do I tell the difference between pressure line, and return line on each cylinder?

 

[J_J]

how do I tell the difference between pressure line, and return line on each cylinder?

Both ports on a DA cyl are pressure ports. Same fitting same hose. The lever on the valve and the correct hook up on the cyl will dictate the operation of the cyl. Pull back, something usually goes up, and push the lever fwd, things go down.

 

[J_J]

Question. If a cyl piston seal never goes past the port opening, is it possible for an air bubble to be trapped at the ends of a cyl, especially with the ports mounted down?

 

[AKKAMAAN]

how do I tell the difference between pressure line, and return line on each cylinder?

If cylinders are double action, both cylinder lines have to be high pressure rated...

Return or pressure line to a double action cylinder, will depend on wether the cylinder is extending or retracting...

All spool valves always direct flow from pump to cylinder, the same way.

Work port closest to lever gets flow from pump to cylinder when spool is pushed in by lever, and same port will send oil from cylinder to return, when spool is pulled out by lever....

 

[JoelD]

Really doubt it is air, the system is ultimately open to the air and continually "bleeds" it's self.

Maybe something got into the valve body?

Pressure guage is best way to check.

Be careful, high-pressure oil can do some real damage to skin.

Joel

 

[AKKAMAAN]

Question. If a cyl piston seal never goes past the port opening, is it possible for an air bubble to be trapped at the ends of a cyl, especially with the ports mounted down?

No cylinder is designed so piston seal can go past the port opening!!

I have never ever had to bleed a cylinder, no matter how it is mounted....

All connections in a hydraulic system are designed to seal for hydraulic fluid.
Air is a GAS, and no hydraulic flange seal or even o-ring seal will hold back GAS at max hydraulic system pressure.

If cylinder is vertically mounted ROD DOWN, yes it is possible for a a FEW cc to get trapped for a while, but that wont show as a total loss of motion on a normal cylinder...

Cylinder mounted ROD UP, always bleeds air easily by the piston and gland seals


Horizontally is probably the most critical position, will trap some smaller amount of air if work ports on cylinder are positioned down...

trapped air can never "lock up" a cylinder, only slowdown the response of the cylinder, till air is pushed out of the system.....
Under high pressure air will compress to almost zero volume, and decompress when pressure is reduced...