Serial number YQU4681 The left hand track is slow until you partially operate the right hand side. Would this be a valve problem or the lever servo that you push to engage the track? Any help is appreciated.
Good day Troubleshooting weak crawlers can be found excatech.org >Library>Common defects>H2 Weak Crawlers Pi Hope that helps Kind regards Uffex
On the kobelco they have a straight travel spool so when you stroke the right side power from that pump goes to the left as well
On the mark 4 straight travel is not selected automatically, you have to turn the kpss switch to position D. Then one pump drives both tracks and other pump drives upper funchions. With kpss in D if both tracks travel at the same speed then you know the problem is not in your motor or turning joint unit.
Not independent travel the l that splits the machine from the tracks. I'm talking about the spool in the control valve that they use to balance travel pressure so the machine travels straight. The straight travel spool.
OK, I have 600 PSI on the pilot pump but only 225 psi at the spool and relief valve for the bucket. What valve or component could be stuck to limit the pilot pressure at the spool and relief valve? I am (almost) certain that the spool is not being opened all the way on either the left track or the bucket hydraulics. Thanks for any help!!
Good day Suggest you make double sure that servo pressure is good, the inlet or "P" ports to the track RCV have filters may have blocked some. Check there is no obstruction to the RCV movement. Kind regards Uffex
Thanks UFFEX. Can you tell me where the filters are? Since both the bucket and left track are slow, I think it may be a valve between the pilot pump and the spool.
Good day The filter I refer too is part of the connection adapter which is between the hose line and RCV, your post has changed it is no longer an individual circuit it appears that the illness has spread. I will try and post an illustration, however I suggest you double-check that servo pressure as the attachment. Kind regards Uffex
Good day Please see atteched, take note of the inline filter at the servo pump, if it hase alluminium particals sure sign of servo pump failure. Kind regards Uffex
You are correct, the problem has changed. The bucket hydraulic cylinder appeared to be bent which is why we thought it was slow. However, when we changed out the cylinder with another, it remained slow.
Thanks!!!! That helps a lot. I will check the screens and report back.
Well, no luck. I checked under both the joystick hydraulic hoses for the bucket and the hydraulic fittings for the travel (foot) valves and all the fittings were the same size.
Good day The fillings may appear the same however if you remove the "P" line and take out the connector you will see the filter screen. Beware have a plug handy fluid will run from open connections. From your more recent posts I am less convinced that is your issue. Please measure the servo pressure at full engine speed and idle, any internal leakage will show up with that test. Kind regards Uffex
Mechanic number 6 is out working on the machine today (for the second day) and cannot figure out what the problem is. Stated all the cab functions are good, the relief valves are good, spools are good. I sent the both the service manual and parts manual to help them. When I left they had the spools out again. Any suggestions what would make the bucket and left track run slow? THANKS!
Update: The mechanic went through each spool and relief valve, cleaned and each and put them back. When done, there was no difference. The pilot pressure was good at spools. They started working on the three electric valves located under the hydraulic pump. One was broken, but they don't think that it may be the problem - but will continue to work on the electric valves. Is there a way to bypass the solenoid valves? Any other suggestions? Thanks for any help.
Good day I am trying to follow the situation with your machine - the original issue was that the left track was slow until you operted the right sde - the bucket is also slow - the pressure at the pilot line of the spool cap is only 225 psi. with full pedal movement (Shoulkd be 600 psi.). The servo pressure is at the pump 600 psi. with both idle and full revolutions. Please confirm this understanding is correct.. When you specify a slow circuit it can be wise to check out the rest of the machine. Regards Uffex
Help, Komatsu excavator model pc220lc-3 serial no. 21496 Thumb and right track at 15% power, about 1987. Could this be hydraulic or valve problem. Picture would be great. Thanks Randy
Did you find out what the problem was with your kobelco excavator. I have a similar issue. But it's the right track slow in forward but it's fine in reverse. And the crowd cylinder is great going out but very week going in like digging. It so bad that it stops when it is balanced and after a few seconds it starts coming in. I can move it back and forth when it gets to the point of balance. Any ideas?
It's a sk200lc mark 4 YQU2944
My machine was purchased out of auction and was screwed up when it was bought. The problem with the machine was that the pilot pump hydraulic lines were taken off then incorrectly put back to the wrong connections. Probably not much help to you, but that was my problem. When the hydraulic lines were put back correctly, the machine operated MUCH better.
I was told that the main hydraulic pump was bad. I checked it out and it was putting out the correct psi. I started looking for the pilot system filters and everyone I found was pretty much stopped up. After cleaning them out it started working. This was at first when I got it. I have cleaned every filter I can find and this is where I am now. I rebuild the pump anyway. It had been replaced 18 months before I got it. The people who rebuild it was a great help. They looked at all the parts after I took it apart and said that it should be fine just to put it back together. I went ahead and lapped everything anyway. But the arm and right forward motion on the track is all I have left to fix.
Thank you for the reply, I had the same issue but it didn't help when I did the same thing.
I have done everything I can think of. I only have one place to go to look for filters. The problem is that I don't have the hydraulic system shop manual. It shows exactly where they are. Go figure you pay 350 for a shop manual and find out that it's a general repair manual. The hydraulic system has a shop manual for it alone so I understand. These are the filters for the negative pressure office. It says it got a filter before it so that it won't get stopped up. But if it is then you don't have negative pressure. I remember the simple days when the only hydraulic thing to worry about was the 3 point hitch hydraulics.
Have you checked the port relief for the arm in circuit? Your travel issue could be a bad relief in the travel motor, you can swap them and see if it changes.
I have a kobelco sk200 mark 4 I seem to have a problem with my tracks not reversing.....when I push forward individual levers I don't get track movement....when I push forward both levers the machine crawls weak and go forward....when I pull the left lever back and right lever forward the tracks reverse the tracks just do not work individually any more...Amy suggestions???