Hi All, I purchased a 2nd hand Kubota KX41-3 excavator, & have problems with jerky hydraulics. Operating the stick & bucket curl is OK, they are relatively jerk free, however when operating the boom & swing of the excavator, it is really hard to be smooth. You have to be super sensitive on the joystick, or it just jerks all over the place, & its impossible to keep up a decent work pace, as you have to be super slow on the joystick to stop the jerking. The jerking is very unpleasant & makes the machine very tiring to use, as does trying to be super sensitive with the joystick to prevent the jerking. It dosnt appear to be joystick related, as I have changed the pattern so that the other joystick controls some of these functions, & the jerk is still there, I also have the same problem with going forward or back with the tracks when manouvering in tight spaces, & I need to go super slow. If the drive contol levers are pushed all the way forwards the drive is relatively smooth, however if I need to go super slow, & need to only have the levers part way pushed forward, the machine again gets really jerky, & will start to kangaroo hop all over the place, which can be pretty dangerous, especially if going up or down a slope. At times it feels like I am going to get thrown out of the seat, the jerk can get so violent. Anybody have any idea what can be the cause of this. The problems seem to get worse as the machine gets hotter, although it could also just be that I am more fatigued, as the problem also exists when the machine is still relatively cold.
Hi Dirtydigger did this problem of jerky travel in slow mode get sorted? If so what was the solution, thanks John
Good day Suggest you check the servo pressure as a first step. Kind regards Uffex
Thanks, put on the list to check, hopefully this weekend John
Good day John I believe your machine the tracks are operated by mechanical means (Rod & Cables) which are unaffected by servo pressure. It maybe that you have two separate issues or there is some history which may give a clue as to the origin of the problem. I have not noted any previous adverse comments in respect of the KX41. Kind regards Uffex
Thanks, I'm afraid I don't have much history on the machine as I have only owned it for a few weeks. The machine was over greased everywhere and someone did mention, when I stated that the tracks did not seem to have any play at all, that they may have been over tensioned by the excessive use of greasing. I have to agree about no adverse comments as I have trawled the internet and found no other reference to the Jerky travel other than dirtydiggers' post on here.
Good day I suggest a good starting point with the crawler controls would be to make sure the lever’s / pedals are free of obstruction and excessive play in the joints & lubricated - disconnect at the main valve spool and be sure the mechanism moves smooth and responds to the lever. Kind regards Uffex
Illustration
Thanks, this would make sense to me, in that a hard push forwards or reverse overcomes any prresure/resistance causing the jerky movement.
First Chance I have had to look at the problem again. In view of the over greasing everywhere I am wondering if the track tension has been over pumped with grease. There seems to be no slack at all in the tracks and I mean no deflection at all even if I stand on them and bounce up and down. I'm sure I have read somewhere there should be a little play in them?
Good day See attached. Kind regards Uffex
Thanks again. I seem to have a problem with the tensioning mechanism. Even with the grease nipples removed, no grease comes out so hence no movement in the release of tension in the tracks. Any other ideas?
"Any other ideas" on releasing the tensioner mechanism that is.
Good day The common reason for the problem you describe is that of a broken spring tension bolt, see attached. Requires the removal of the track belt for repair. Kind regards Uffex
I've now managed to release the over tensioned track rubbers, which has helped a little in reducing the jerkiness. It is still there however and is not pleasant at slow speed due to still jerking very much. I did notice as well that the 2 speed function doesn't seem to work. I'm sure the other day that at least the light indicator worked but it isn't now. There are beeps when you press the green 2 speed button. Getting a steep learning curve on this machine.
I recently purchased a used kx41-3v and am having the same transport issues with jerkyness. Have you had any success in fixing the issue?
Not as yet. I did have someone look at it and when he drove it on the gravel it wasn't as bad as when it was on the concrete. He was of the opinion that he had driven worse. He did think that there was more play in the swing bearing than there should be. I did look at this video posted here which is a very clear and concise explanation of what is involved to replace it. HeavyEquipmentForums At present I am still trying to sort out the lack of two speed travel, as I still only have low speed. So far, I have established that the two speed switch on the joystick works and beeps correctly. All fuses are ok and relays all seem to latch that are to the left of the fuse block. I haven't as yet identified the speed change solenoid. Ideas on where to find it would be appreciated. I'll keep you posted if I come across a solution. Good luck John
I have just purchased a kx018-4 that has the same issue with jerkyness when travelling forward very slowly. Did anyone solve this issue?
Having same issues with my kx41-2v… Any info would be much appreciated!
I have a KX-33-4 that appeared to have a problem that I'm a bit embarrassed to admit. While traveling it would "jump" or hesitate then surge in slow or rabbit mode. I'm a big guy and I realized my left thigh was very slightly pushing the left control just enough to rob some hydraulic supply. Simple solution in my case, don't sit with the legs spread.
Thanks for the thought, but not the case for me. Something else. Trying to figure out if relief valve, check valve. Not sure where to start.
Do you have any test gauges? I assembled a set of 4 today to help diagnose problems with my grader. About $110.00 each.
Ordered a kit yesterday. Should be coming in today. Replaced the hydraulic oil and suction filter… the other filter’s stuck!! Going to try to remove again later today if the rain stops. The suction filter was pretty dirty with particles in it. Pretty sure it’s been in there for a while! Still can’t believe how tight the other filter is and what’s the purpose of over tightening it… especially when there’s a set screw at the top to keep it in place. Anyways, will get back once I get back on the machine. Regards