Hydraulic Counterbalance recharge

[Kool Parts]

In the Haas service manual it shows a recharge kit...has anybody used this to just raise the pressure? I need to add a 100#s or so.
Gary

[serviceman]

just be very careful opening and closing the valve on the nitrogen tank if you do not have a regulator as soon as you crack the valve on the nitrogen tank you are opening up about 2000 lbs of pressure so it starts filling the tank right away. you should be very careful.

[Kool Parts]

No regulator...now that would take balls.
But I was thinking of Acetylene in stead of Nitrogen so it would have more...bounce

[HaasTech83]

I have a kit just like that, without the regulator. I'm going to buy a regulator for a several reasons.

It would be much safer.

You can set the correct pressure before opening the schrader valve so you don;t get oil in your fill hose.

You will have another gauge to tell how much pressure is actually in the tank, sometimes the machine gauge is off.

[Kool Parts]

Yes its called a High-High regulator (both gauges are 4000#) I have trans filled more than a few cylinders over the years...but none with oil in them...

[qualitytool]

had mine charged by factory service he used a tank and hose cracked valve on tank very slowly to charge cylinder

[Mike K]

I'm new to this forum and couldn't believe the timing of this thread.

I just went through this filling process and it really sucked.

I noticed the pressure was a little low and hooked up an unregulated nitrogen bottle. The valve was very tight and when it finally let loose, I overfilled it by about 100#. It didn't take long at all to let too much in. Being a compulsive type I tried to bleed it down a little.

Bad idea! The only thing that came out was hydraulic oil. I saw the error of my ways and decided that a little extra pressure wasn't so bad after all and proceeded to disconnect the nitrogen line.

Oil everywhere! The stupid Schrader valve had failed! I tried frantically to cap it but there was no way I could overcome that kind of pressure. So I watched the oil bleed out until it was almost gone, at which point a pink fog started spewing out.

Then, as the pressure dropped to 400# the head started dropping!! Fortunately the spindle was over an empty space between a vise and rotary table. It actually slowed down near the bottom of the travel and came to a gentle stop that didn't damage anything but the bracket that the programmable coolant nozzle mounts to. The spindle didn't touch anything. Very lucky!

So then I had to refill the bottle with 2 quarts of DTE 25 oil, replace the Schrader valve and recharge the system.

I did all that, and wouldn't you know, as I was removing the nitrogen line oil started coming out again! The new Schrader valve failed too! This time I hadn't yet fully removed the fitting so I tightened it back up and left it there. Still hooked up to the refill bottle.

So, if I had it to do over again, here are the things I would do differently:

1. Make sure the valve on the fill bottle can be cracked open easily. It would then be easy to avoid over filling.

2. Bring the head down to a block of wood so it doesn't have anywhere to go if you unexpectedly lose pressure.

3. If I ever bleed it down again, I will install a high pressure needle valve between the Schrader valve and the system. With this, I won't be depending on a tire valve to hold 750# of pressure. It will make filling a lot easier to control as well.

Good luck!

[serviceman]

i have had the schrader valve fail on me as well it is a scary thing it is not a bicycle valve though schrader bridgeport http://www.schrader-bridgeport.com/i...cation_id=1134 they sell the valves and the fitting to fill the tanks a regulator always helps and if you invert the tank before you start you will not loose as much oil. you really do not want to breathe misted hydraulic oil i always wrap up the end of the hose with rags shove it in a bucket and walk away when i discharge the tanks.

[HaasTech83]

You should always have the Z-axis all the way up when you charge the system to get the correct pressure. I always leave the servo's on the prevent the head from dropping, but you must remember if you loose the pressure that nothing is going to keep that head in place during e-stop.