Have a 140G with AWD that is not working. Seems like most everything on that system points back to the charge pressure which should be 450 psi with AWD off and 350 psi when it is on at idle. I only get 60 psi no matter what I change the pressure relief to. There are 2 charge pumps that Tee together before the filter and pressure relief. How would be the best way to test one or the other separately? Can't imagine just plugging the output of 1 to be a good idea.
Pumps provide flow, resistance causes pressure. You probably need to use a flow meter to see what each pump puts out, at the specified pressure. Or on the outlet of the relief valve to get total flow. Lack of charge pressure usually means something downstream, either a drive pump, or motor, or valve, is bypassing off to the case drains, there should be a specification for case drain flow from each pump and motor.
Here is where I am at. To eliminate all the functions off the charge pump I capped the output from the filter so it basically comes in on the hose to the right of the filter from the 2 charge pumps, then goes out left to the valves and up to the pressure relief, Tees to another return then back to tank. My theory was if I eliminate the valves from the circuit its just going from pumps, to filter, to relief then back to return. Even in this configuration even adjusting relief can only get 60 psi idle.
I see you say you have tried adjusting the relief valve but have you opened it up to check if anything is broken internally such as a poppet spring..?
I removed the pressure relief from its housing and tightened and loosed in and confirmed it changes the amount of force required to push the fluid side in.
So you didn't disassemble it then..? Do you have a Parts Book and if so what is the Part Number of the relief valve..? Also the machine Serial Number would help.
should also note that the return goes through the cooler and there is a cooler bypass with a 60 psi relief valve there. Thats what made me first think the main relief is stuck and I'm in that 60 psi range because of that cooler relief. When I took the main relief apart I loosed it all the way and I could fairly easily push the pin on the inlet side then I tightened it all the way and I could still push it in but had to rest it on the bench and put a little umph into it. Is there an easy way to test the pressure relief? Maybe I can swap it out with another one on the machine?
The book I am working out of is the Supplementary Product Support book for the AWD system on the 140G. Book number SEBF0600-01. The machine s/n is 72V13881.
SEBF0600 - I was afraid of that. The AWD literature on the 140G back in the day was all Custom Shop stuff which was only ever produced in paper form and doesn't appear in today's online systems. Without access to any data on the system I'm lost I'm afraid. I've never worked on an AWD but with access to a hydraulic schematic and some test & adjust information I could probably figure it out. Without that - no chance.
Looks like the relief is p/n 3Z4681
Looks like a plumber's nightmare? Got a schematic there you can scan up for Nige and I, and anyone else that might be of help?
here is the relief
Description of the charge system in the book. I think the way I have it now with the valves plugged off from the filter it goes from tank to each charge pump which are piggy backed on the main pump. From the charge pumps they Tee together and go into filter housing. Out of filter it only goes to the pressure relief then back to the cooler and cooler bypass relief then back to tank.
Here are some of the schematics Left pen is pointing at the pressure relief and hoses going to the freewheel valve, etc that I currently have capped off. Right pen is pointing at the charge pump that mounts to the AWD pump This shows the return after the relief that goes back to the cooler and the pen is pointing at the 60 psi pressure relief cooler bypass.
3Z-4681 is a Custom Shop Part Number and doesn't appear anywhere in the online system unfortunately. It's made from 9T-6204 but even that isn't used anywhere in the system - bugger. Those photos are the parts manual which although it shows us where everything is it doesn't tells us how it works. Is there a Hydraulic System schematic anywhere in that document that looks anything like what's shown below - this is a section of the hydraulic schematic from the AWD system of a 140M.
Here is a picture of it. Linking to it so hopefully it stays in a larger resolution to see it better https://drive.google.com/file/d/0B5oqdBnWEkKbbU1yd0xOek1XMGs/view?usp=docslist_api
The 25cc and 18cc are the charge pumps
That schematic helps a lot and I think you are on the right lines with your troubleshooting. So in your first photo, the relief valve is in the block to the left of the filter, correct? To eliminate the relief valve, I suggest capping the line from the filter so you are effectively dead-heading the pumps. Don't run the engine in this condition but crank it over on the starter motor whilst carefully watching the gauge. You'll soon know if you are building pressure or not. If you still can't make pressure then either both pumps are faulty (unlikely) or one of the pumps is faulty and letting the flow from the other one back through. You can pin point which pump by disconnecting them in turn where they tee together, cap the tee, run the free line into a bucket and repeating the test. If you get this far, I would bet a dollar on the drive coupling to the end pump having failed.
That schematic really does help and I can't add much to the procedure suggested by CM for troubleshooting the system. Trawling through the information that is available it would appear that the Transfer Gear Gp (aka pump drive) for the AWD system was the Achilles Heel of the AWD machine. There have been various mods over the years, some of which apply to your machine and some don't. One of the mods is an improved input shaft, a later mod from 72V16373-Up was a complete new Transfer Gear Group. There is also a very comprehensive procedure on disassembling & reassembling the unit and reading the level of detail it contains leads me to believe that either it was difficult to get the bearing adjustments correct or there was no detailed information out there in the first place.
Now that would be interesting... dual charge pumps which is odd, one pumping happily, the other spinning backward due to a sheared shaft? Hmmm.... LOL
After reading the documentation regarding the drive for the 2 pumps my money would be on a sheared input shaft. It's gone through so many iterations it will make your head spin......
Ok, this morning I capped the output of the filter housing (the pressure relief is that block left and above the filter) and on the starter only saw 15 psi. Had a guy watch gauge so I could fire and shut down quickly and still only saw about 50-60 psi. Then unhooked the Tee between the pump and capped one side then the other and for sure the pump on the left side of the machine is not working. Pump on right side hit about 400-500 psi in the few seconds machine ran and when I had that side unhooked (first of course) it pretty much rust proofed the shop floor for about 25' radius around the machine..... . Will start digging into that pump next and try to decide if pump or shaft. I cut open the old filter and it has some metal in it but IMO nothing excessive.
Do you have a photo of the particles that came out of the filter..? TBH it shouldn't have anything that's visible to the naked eye if the system is in good shape. The fact that it has is somewhat perturbing.
Here is a picture of the opened up filter off the charge pumps. This filter is about 500 hours old.
Panic over - I see nothing to worry about there. From your post #22 I got the impression there was a significant quantity of metal in the filter. Next step would be to check if the pump input shaft is broken,
didn't think it was too bad but thought it might be worth cutting into the filter to see. Just big enough particles to barely see but not full of it either. Wish it was the other side since that pump is basically a bolt on pump, the left side is integrated into the AWD pump. Will start tearing into it next...
Well, found the problem in the charge pump off the AWD pump. Now to try to find a part number and order one.
If that's the charge pump that's mounted on to the end of the Piston Pump I think the Part Number is 6E-5074. The complete Pump Group is a 3Z-4624 which is a Custom Shop build. PM me with your email address and I'll send you the document I found with the details on it.
that would be great, thank you. Looking through my book I have the picture of the 3z4624 and it has this pump drawn up but no number for it. Can find the other charge pump off the implement pump but not this one anywhere in this book.
If the document Nige is talking about is the one regarding the updated head and charge pump assembly, you probably know by now that it is no longer available. If you post a photo of the entire pump, someone will probably recognise the manufacturer.
I suspected that. The complete pump is listed as "contact dealer regarding availability" but there is a price against it which usually means it's available based on a confirmed order although not necessarily kept in stock. The wheel motors for the AWD front wheel drive system were made by Poclain, I wonder if the pumps were also..?
Just talked to the guy at the used parts dept at cat and he found me a new one in Ohio for $2500.
I've seen a service mag showing a breakdown of the pump and it looks to be the same design as the drive pumps on a 953C. We repaired one a couple of years ago and I think, but not sure, they were Rexroth.
That's pretty much the price I saw when I checked.
Its on its way and hopefully gets our front end working again so we can start sloping canal banks. Thanks for the help!
Well got the pump installed last week and they have used it a little and seems everything is working good again. Thank you for the help.
Nice to hear a success story.