IT28F need help with hydraulics

Hi

I have an IT28F that abruptly failed the tool tilt system.

The tool holder just hangs all the way down and even if we lift it bake up it just falls back down.

I had resealed the right hand tilt cylinder several months ago so I remove the hose from the extend port of the left hand cylinder and tried to retract the tool holder, large quantity of fluid flowed out of the cylinder and no fluid out of the extend hose with no movement of the holder. This indicated that the piston seal had failed. So removed the cylinder and resealed it.

Today after installation of the cylinder I tried to retract it with the extend hose removed. This time I got large amounts of fluid out of the extend hose and nothing out of the cylinder.

Now I am convinced there is a problem with the control circuits. This machine uses hydraulic pressure to operate the main hydraulic valve located under the machine just behind and above the front axle.

Is there anyone here that is familiar enough with this machine to give me some trouble shooting advice to find the location of the problem?

Phil P

hi, serial number please. did you isolate each cylinder as they operate in parallel it may be that the cylinder you repaired has failed again more info please
Mark

I agree with Mark250, the most likely scenario is the first cylinder is now leaking past the piston again. You might try disconnecting both lines from the right hand tilt cylinder and plug the ends of the lines. With no load in the bucket the left hand cylinder should operate normally. Oil will shoot out of the open ports on the right hand cylinder.

Or, if it's possible, you may have gotten the two lines swapped somehow?

OK

I will get SN today.

Here is more information.

I have now connected the upper hose and removed the lower hose. When the control is moved to retract both cylinders I am now not getting fluid out of the lower hose. I have the upper end of the cylinder pined with a 1 ¼ inch pin so I should see some kind of moment. The cylinder is not receiving any power as it doesn’t even wiggle.

It is obvious the control system has failed in some way.

The operator said he had rotated the bucket down so he could use it to push dirt and when he pushed the system failed like a hose had broken. However there are not any hydraulic leaks.

Phil P

S/N 3CL00239


The machione is now porting fluid to both side of the cylinders at the same time.

Possible you have port relief issues....

Not familiar with this machine but just thinking out loud. Is it possible a piece of the failed seal from the resealed cylinder has now worked it's way around the system and is holding a check valve or something open? If it would help I could upload the schematic for the hydraulic system. Hate to have to admit it but I never got too good at working with those.

Hi

Yes a schematic would be of great help.

Thank you

Phil P said:

Hi

Yes a schematic would be of great help.

Thank you

Click to expand...

Here you go, hope it helps!

hi ,here is section of schematic and photos of line relief locations also ghost view of control valve, if you are positive the cylinders are ok there is not much left to check. these old girls are basic as

Thank you both.

I had come to the conclusion that it had to be in this valve.

I will let you know how I make out.

Phil

Most likely one or both of the line relief and makeup valve cartridges, there's not much can go wrong with the spool section.

Thank you Iantraxo

That would have been my first part to remove. Can you tell me if they come out as a cartridge? If so can they be disassembled? How about fluid will it free flow from the main tank or will the valve keep it from draining?

Yes, I think so, and not sure. You may want to have something handy to plug the hole with. I usually pull a vacuum on the hydraulic tank anytime I break a connection, or at least cap the tank with a zip lock bag and some rubber bands to create an air lock, usually helps.

It looks like there's a threaded section that unscrews to let you pull the innards out, keep careful track of the order and orientation of the parts.
Try not to change the settings if you can help it, or if you need to unscrew the adjusting screw, mark it or count the turns so you get it back close.

Well here we go.

First the machine is repaired and back in service Friday 7/15.

I found a fellow that works for CAT that has been around long enough to have worked on the IT28F and knew it very well. He agreed with all the information I have received here so I drained the hydraulic system by removing the tool lock line and pumping the fluid into a 55 gallon drum that originally had hydraulic fluid in it. When I finished I pumped the fluid back in to the machine thru a 10 micron filter.

I went thru the “B” element of the main hydraulic valve I removed every valve and both ends on the spool valve to make sure there were no broken springs or contamination.

This did not fix it.

So I did something someone had recommended. I caped and plugged the hydraulic line and cylinder port of the cylinder that I had sealed about 3 months ago. Had I followed the suggestion 2 weeks early I would have had the unit repaired in 2 days.

The system worked with the line caped. So I retracted the tilt system all the way up and chained it so it couldn’t fall. When I removed the cylinder cap the shaft fastened to the piston just fell out. I had to “fish” the piston and retainer bolt out of the cylinder with a pipe and wire hook.

There was no seal damage and the bolt had lost only the last 1 ½ threads. Liberal amount of Red Locktight and the ¾ impact wrench put it back together and had it assembled and back in service in about 3 hours total.

Thank you all for your help.

Phil P

Glad we could help
Mark

I would like to suggest you that please check your entire system so that you can actually understand the issue of your machine. Use proper strapping tools for it so that your can easily assemble and re-assemble it.

Hi

Just so you all know this stuff I am working on is used in a large agriculture research facility (11,000 acres) and most was wore out when they purchased it. LOL

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regards
angela belly
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