I have a 322 mini ex that I bought for a project knowing it had the issues. Ive got the manual for the machine but I'm not a hydraulic mechanic necessarily. All 2 speed functions work on the good drive, good power, and good speed. The other side is all but dead, I can stop the track with my hand if the tracks are off the ground. Ive tried swapping lines from one to the other and the problem follows the hydraulics not the drive motor so the motor is good. The pump seems to be good because all the functions running on the same pump function. I don't have a hydraulic gauge for testing but have one ordered. It seems to be a simple system and I don't see anything other than the valve or a blockage in the valve causing the problem. I guess it could be a check valve in the manifold or something, but the manual does a poor job of labeling part locations in the manual so I have no idea which valves to even check on the manifold.
Good day May be best to begin checking that the spool for the lame track is shifting as it should. Kind regards Uffex
Thanks for the quick reply. The valve is physically moving the full stroke or appears to be compared to the other drive valve. I was hoping not to have to pull the entire valve block but looks like thats where its headed lol Don't think I can get the spool out without pulling the entire block.
Good day That's a lot of work, have you checked out the central joint. Make the same test prior to the central joint to determine that the MCV is at fault. Kind regards Uffex
I will check that out as soon as I get my gauge set in here.
Is it that common for the swivel joint to cause drive issues? I assume the cause would be the seal between the two drive lines would be leaking basically bypassing the drive motor? Ive replaced swivel joint seals in my bucket truck so its not completely foreign. I checked case drain flow of each motor and the one that is not functioning is less than the one that isn't functioning proving its not getting th eflow it needs. The engine also lugs when I activate the drive motor on the non working track, meaning there is a clog somewhere more than likely? Or am I wrong in that assumption?
The engine loads up when running the weak side? Undercarriage components aren't sticking/seized up?
No they are free. I pulled the track and all bearings are good. And also swapped lines from the good side and it functions correctly and the problem moves to the side that was good. n Which makes me think the valve is actually good. Short of a complete blockage in a hose I am lost. Im pulling all the hoses on that side tonight to check to see if they are clogged.
I'd test the center swivel. Could be bypassing.
Good day Blockage or clogging of a main line is totally alien to me, it is possible to get port cross over from seal failure on only one side of the crawler drive. Experience of central joint failure is far more probable than the MCV being at fault. Equal pressure to both "A" & "B" ports would explain the engine loading. Illustrated, a typical Bcat central joint (Swivel Joint) Testing and identifying faults often involves some work. This is not only of an immediate benefit fixing the machine, the knowledge and confidence will also grow. Knowing your machine can also save you money. Guessing is a gamble and on some occasions it will pay off especially when the fault is a known issue, systematically working through a system.
Thanks for the input. I was planning to rebuild the swivel joint anyway as it has a bad lower seal only evident when operating the blade which is the lowest section of the joint. I did cap the lines at the motor and blow air through the hoses and there was no bleed over between the hoses, but I do realize the hydraulic pressure is much higher than 165psi. As soon as my gauges get here I’m going to reassemble everything and get some readings. I’m leaning towards a bad pump at this point. That same pump runs the boom rotation which is terribly slow, the boom up and down which is slow and honestly haven’t used the machine enough to know if the down force is what it should be.
Just a quick update. So I filled the machine with fluid again today after losing so much swapping lines around. The fuctions on one pump all function flawlessly slew, blade and auxiliary are on that pump. The functions on the other two pumps are really jittery/jerky when opening the valves to max and functions are much weaker than they should be. Boom and arm will not pick the machine up but bucket will (which is odd). Right drive motor works fine although is slower than expected, but left still won’t do anything at all other than a creep that I can stop with my hand. I’m the manual all troubleshooting charts point back to the main relief valve being adjusted wrong or bad. However I don’t see how that could effect the track without another issue in that circuit. I am hoping to have the gauges tomorrow but I don’t have a way to test the flow. I’m guessing bad pumps at this point.
Good day Michael The most recent post paints a slightly different picture, could you post the hydraulic schematic & index we will try to help some more. Kind regards Uffex
Here’s the schematic and index.
Hi Michael The schematic refers to 320 however it maybe the same, a point that jumps out is that the three pumps use a common relief valve separated by check valves. Should one of these leak it could result in the issue you have. A simple check you can make operate the sick circuit and then pressurize the good one's, if it recovers it most probably is the check valve. Make the same test with both bucket & slew. Kind regards Uffex
320 and 322 are identical except the 322 has a track width adjustment cylinder which is out of the equation because it was leaking and capped off.
It did recover at times to full speed when operations different circuits. But after further tests slew is strong one way and weak the other. Boom, slew left, and bucket are the only circuit that are consistently strong and moves within specs. All other functions are either jumpy/jerky at max open or very weak at times yet function at other times. Another thing I notice is bucket controls are backwards from what they should be, Left is out right is curl. Probably just two reversed lines when last owner hooked it up wrong I can figure that part out.
I was incorrect about the schematic. It had a serial number split. It has more valves in the manifold.
Good day Michael You are having a number of issues, I suggest taking them as individual problems. If I am interpreting your post correctly, pressurizing the other circuits resolved part of the problem? Switching the pilot lines for the bucket is fairly simple, an issue with slew in one direction only generally points to the valves in the swing motor head. Please see attached. Kind regards Uffex
Good day omitted If you could post your manual on a Gmail drive and post me the link, I can make better details of the swing issue. KR Uffex
Yes sir. While activating the sick circuit then moving other functions of the machine it did in fact make the track go to full speed at times. It wasn’t consistent but did function and have power. Here’s the manual. Any help is appreciated. This manual assumes you know where the check valves are because the book does a poor job of showing locations. And I agree to having multiple issues. Lol https://drive.google.com/file/d/1gsN5jwQLF35uxMEHbQW74zqTXZOCt4uu/view?usp=drivesdk One thing I noted was when I pulled the input hoses from the pumps to the manifold…. One input had zero leakage, one had a slight trickle and the third was pouring oil, which should not happen if I am reading the check valves in the schematic right.
https://drive.google.com/file/d/1gsN5jwQLF35uxMEHbQW74zqTXZOCt4uu/view?usp=drivesdk
Got my gauges in today. Ran the tests and they were kind of all over the place. This is high idle tests best I can do on my phone. In order after joystick. Second pic is wot readings. According to my gauges. Not sure what it means but operating tracks the good track was at 500 psi at test port g the bad trac was 2500 Blade is very very slow as well but works and has plenty of power.
Update on the issue I’ve been having. It’s been too cold and nasty to work on the machine lately. Yesterday I got it all back together. Things I have done are Rebuilt all valves in the manifold block Rebuild the swivel joint. replaced some of the hoses. Same exact symptoms as before. Drive will not pull at all unless weight of the machine is off the ground. There is little to no case drain at either drive motor. The bad drive will pull when off the ground. While moving the machine I activated high speed and the machine lugged so bad it almost died. I did notice if you bottom out arm while traveling the bad motor seems to pull somewhat harder and the good track runs a good bit faster, which I thought was odd.
Good day Michael I suggest we go back to basics, are we sure you do not have a mix of motors on the machine? If the labels appear the same, switch the motors and let us see if the problem shifts before we move on. Kind regards Uffex
Yes sir. Same identical motors. Appear to be originals. I will swap the motors one more time. Unless I got confused I almost positive when I did it last time the problem followed the hydraulics not the motor.
so I got home today swapped the lines on the final drives and the problem follows the hydraulics, meaning the issue became the same exact symptoms on the other final drive, no power and very low speed.
Good day That is good diognostics we either have an issue post central joint or plumbing iat the joint, is it possible some lines have got crossed? Kind regards Uffex
Good day Can you measure pressure both main lines to the travel motor when you activate the right side, inside the main valve you have a couple of chokes, we can tell if this is the trouble by cheking those pressures. Kind regards Uffex
I can do that. I cap one line at the motor and test the other and then reverse the process correct?
Good day Michael I have been looking deeper into your trouble, befor we suspect the valve can you please check out the attached, The switch see if this is pulling the solenoid when you activate the right side spool. Turn the key on, no need for the motor to run pull the spool and see if you got power. Kind regards Uffex
Will do. I think we may be into something here. But would we get any motion of the solenoid wasn’t opening? Just a question.
I do have power when I pull the spool and machine is in high speed. Solenoid is activating as well or you can hear it activating whether it’s actually switching or not or not i don’t know. It only activates the solenoid in high speed though not in normal operation.
Good day Michael From your post it sounds as though the solenoid is shifting, the check valves within the manifold must be leak free to prevent the issue. I will make some information to help out may take a little time. Kind regards Uffex
Good day Michael I have taken some time to look at the problem. We can be sure it is not the track motor and because we can get high speed on one track means the valves are shifting correctly. The manifold could be suspect but I cannot see any obvious reason for the fault. I have made the best from the Bcat information but there appears to be a contradiction of which valve is which so I have attempted to straighten the parts out see attached. Please check it is connected correctly. Kind regards Uffex