Cat IT28G need hydraulic schematic

[Will-Power]

Hi all, I am new here, been following for a while. I have a customer that has an older Cat IT28G loader, the work functions stopped and he cant lift or tilt the bucket. The steering circuit works fine. I checked pressure going into the HRC (Hydraulic Remote Control Joystick) for the work functions and there is 300 psi going in. I didn't check the pressure coming out of the HRC for the functions. I removed the pilot pressure control valve for the HRC and it looks fine, and I also removed the relief valve for the main work function valve, and it doesn't appear to be jammed or have contamination in it.

My guess is that the HRC is bypassing oil directly to tank and not allowing oil to go to the work functions. It would be good to have a schematic for this loader as the customer bought it at auction and has nothing of course.

Also the hydraulic cooling fan circuit is not working, I havent looked into this yet because I would like to see the schematic first.

Any help would be appreciated.

Thank you,

Will-Power

 

[kshansen]

Hi all, I am new here, been following for a while. I have a customer that has an older Cat IT28G loader, the work functions stopped and he cant lift or tilt the bucket. The steering circuit works fine. I checked pressure going into the HRC (Hydraulic Remote Control Joystick) for the work functions and there is 300 psi going in. I didn't check the pressure coming out of the HRC for the functions. I removed the pilot pressure control valve for the HRC and it looks fine, and I also removed the relief valve for the main work function valve, and it doesn't appear to be jammed or have contamination in it.

My guess is that the HRC is bypassing oil directly to tank and not allowing oil to go to the work functions. It would be good to have a schematic for this loader as the customer bought it at auction and has nothing of course.

Also the hydraulic cooling fan circuit is not working, I havent looked into this yet because I would like to see the schematic first.

Any help would be appreciated.

Thank you,

Will-Power

Will try to help with schematic, but , need at least the prefix for the machine S/N.

Found at least two different schematics: One for WAC 1>UP and DBT 1>UP, the other says it's for 8CR 1>UP and 9AR 1-UP

 

[Will-Power]

Okay great thanks, serial number is 4TF65434. Pin is 8CR02862.

 

[Nige]

Just a thought. You are probably going to need the electrical schematic as well, in order to see where/how the signals come from for the fan control valve.

 

[Will-Power]

Yes you are probably right Nige, so if anyone has an electrical schematic that would be helpful as well.

Thanks.

 

[kshansen]

Yes you are probably right Nige, so if anyone has an electrical schematic that would be helpful as well.

Thanks.

Attached should be PDF files for both the Electrical and Hydraulic schematics.

Hope they help,

Would have posted earlier but had a couple bikes that needed riding and some Ice Cream to get on the way, hope the delay was not a problem!

Ken

 

[Mark250]

hi, did you check the hyd lock out lever. people forget what they do on these old machines


there are two main things I would check
the main relief which is at the left rear or main control valve unless it has optional 4th valve installed in which case it is in the add on valve .if this is ok I would pull the back off the main (rear) vane pump and check the cam ring and the splines on the shaft and rotor
the splines wear out and the cam rings crack
The fan drive is part of the brake circuit with a priority valve protecting the brakes. there are no electrical controls that can cause issues
check the pump pressure at the test port on fan/brake pump on engine .if pressure is ok check the relief valve in the fan motor first
Mark

Mark

 

[Will-Power]

Thanks for the help Ken and Mark, I will let you know how it goes.

Cheers

 

[walker ag]

Hi all, I am new here, been following for a while. I have a customer that has an older Cat IT28G loader, the work functions stopped and he cant lift or tilt the bucket. The steering circuit works fine. I checked pressure going into the HRC (Hydraulic Remote Control Joystick) for the work functions and there is 300 psi going in. I didn't check the pressure coming out of the HRC for the functions. I removed the pilot pressure control valve for the HRC and it looks fine, and I also removed the relief valve for the main work function valve, and it doesn't appear to be jammed or have contamination in it.

My guess is that the HRC is bypassing oil directly to tank and not allowing oil to go to the work functions. It would be good to have a schematic for this loader as the customer bought it at auction and has nothing of course.

Also the hydraulic cooling fan circuit is not working, I havent looked into this yet because I would like to see the schematic first.

Any help would be appreciated.

Thank you,

Will-Power

Was this problem ever figured out? I'm having the same problem with one of our loaders doing the same thing, it will get all the hydraulics back if you shut off the loader and restart it, or if you move the steering wheel back and forth while trying to raise the loader.

 

[kshansen]

Was this problem ever figured out? I'm having the same problem with one of our loaders doing the same thing, it will get all the hydraulics back if you shut off the loader and restart it, or if you move the steering wheel back and forth while trying to raise the loader.

Walker, Kind of don't think he is going to respond as last time he was on the forum was Nov 6, 2016! Just another case of someone finding the forum asking for help and then disappearing. Hope the guy is okay and just had a computer meltdown and forgot how to find us again.

Maybe jump-starting this thread will get someone's attention who can help. Not sure if there are any trouble shooting charts on SIS that would help. I'll try to look and post here if I find something.

Well I looked and not any real trouble shooting info right off.

I looked in the Systems Operation on Hydraulics and see this, which you may already know:
Oil for the pilot circuits flows from the steering pump. The oil flows from the pump to a pressure reducing valve. Then the oil flows into an accumulator and on to the pilot control valves.

So it does make some sense that working the steering can effect a "cure" of some kind. I'm going to attach the full System Op to the bottom of this message on the chance something in there give you an idea of something to check!

 

[walker ag]

ok thank you kshansen I'll give that a look and see what I can figure out hopefully I can get some more info to help figure out this problem.