I had noticed my right hand track has been weak in the forward direction since I started using this machine earlier this year. Serial #7547 Recently a couple times it went from weak to not moving at all - even when lifting that side off the ground - still would go backwards full speed though. I had decided that the hydraulic rotary joint must be leaking, but today I think not. I noticed today that the lever felt like it was not moving forward freely like it does backwards and like the other lever does forward and back. Opened it up to check the cables and adjustments and they all looked fine. So with the lever jammed forward, at first you cannot hear any oil flowing, hold it long enough and the track slowly starts to move and you hear oil flowing hold it long enough and the track will get up to about 1/2 - 3/4 speed, and the noise of oil flowing fades away. Additionally I found that if I operate the boom down function the track will speed up but the boom will not lift the machine with the travel lever and the boom lever operated at the same time, lifts immediately though when you let off the travel lever. I have come the conclusion that there is something haywire in the valve not letting that spool move in the forward direction freely. This is based on the feel of the lever and the intermittent nature. If I lift it up get it going good forward, sometimes the lever will feel like it’s moving forward freely. As long as I keep going forward travel is fairly normal. If I back up, then it slows back down when I try to go forward, and the travel lever will then feel like it’s not going all the way forward again. I had replaced an aftermarket hydraulic solenoid valve for the thumb function when fixing all the other issues this machine had - inside this valve there were some pieces of plastic stuck in it. I am wondering now if this is what’s going on with this travel spool. Sorry this is so long! Would appreciate anyone’s thoughts/ experience with this. Thinking of tearing into that valve body this weekend.
Good day From your description our thoughts are either spool not shifting correctly or leaking shock valve, we guess that the shock valves are installed to your motors one for forwards and one for reverse switch them see if the issue moves to the other side, word of caution you no doubt have open centre spool on the tracks so be aware fluid will flow when you pull the valves out, make sure you have released residual pressure before you attempt the switch. Kind regards Uffex
Thanks for the reply! I was not aware there were shock valves! Are these normally located at the final drive motor? Will have a look at my manual and see if I can find them.
Good day Batkom If you have a picture of the drive motor email this to us we can help a little more, if you have an hydraulic schematic it would be even more helpful. Kind regards Uffex
I believe that machine is CLSS system which is closed center. You need a schematic to troubleshoot the problem.
This reminds me how hard it was for me to understand the OLSS but I finally got it! Then I newer used it - and forgot, only thing remember is something about jet stream distrupting return oil flow and creating pressure drop.
Spent some time last night looking over the service manual I have. Could not find mention of a shock valve. Did looked over the valve disassembly, looks pretty straightforward. Will open it up tomorrow n see what i find.
Update Started to pull track spool first without removing hoses n valve body. I will never know if there was something in there or not! The volume of oil that rushed out would have flushed it out! Went ahead and removed the body completely, disassembled and cleaned and thoroughly inspected. Someone had been into these before and there was an obvious deformation on the track spool where something had been in there. Also found similar on the boom spool. It had been cleaned up, but not very well. Inspected the spool bores with a borescope and they did have a couple small scratches in them, but looked suprisingly good. Stuck spools in a lathe and stoned any minute highs off with a superfine ruby stone. Spools all fit very well, almost snug, just a little drag. So I have reassembled and am now working on replacing the final drives. Have one leaking hydraulic into the gear side. Found it is going to be cheaper just to replace both than try n get parts n rebuild them with the down time n labor n parts.
Also, the travel lever moves freely both directions throughout the travel. There definitely was something in there, cause it never moved free like that before
Finish drives install today, and put it all back together. Tracks straight, tracks have lots of power! Pushed some dirt and it works awesome now. Did some digging, and there was an improvement there as well, quicker response and slightly faster. I attribute that to the sport Beijing sticky and stuff floats around in the valve. Time well spent!
The spools being sticky! Stupid autocorrect!
Glad you fixed it!!!