I have a Kobelco SK150 MK IV that I recently acquired. I am new to the world of heavy equipment so bear with the stupid questions. This machine has an issue with one track running slow - maybe 70% or so of the other track. This is a problem on both high and low track speeds. At the advice of a friend I have checked for crimped lines, leaks, etc. and cant find any. Any other ideas other than replacing the track motor or how I can further troubleshoot? I suspect the hydraulic fluid may be a bit low but have not topped off yet. Cant imagine this is it. Thanks - love this forum. :notworthy
It may well be your slew joint, this is the joint in the middle of the machine that the track motor pipes flow througth, the seals may be gone! This would be your cheapest way out! You can do a simple check on the motors them selfs, remove the covers on the back (between the two tracks) and you ll see the pipes there should be three pipes two large one small, if you remove the small one and have someone in the cab to turn the track( with it of the ground) and see if there if any oil coming out of the motor, there should be a small amount not much, if there is a fair bit you have a problem in your motor! Hope this helps CPS
thanks CPS - can you explain the logic around the motor test (not sure what the small line is vs the larger lines). Would like to understand it. If I crawl under the center of the machine and look up at the cylindrical unit that the pipes are distributed from - is that the slew joint? Is that where the access is to check it? sorry for the basic questions - still getting aquainted with this machine......
Sure thing, the two large lines at the motors are the travel direction pipes 1 forward 1 reverse as such! The small line is whats called the case drain, this allows excess oil in the motor to drain back to the tank! Like i say there should be a small amount (kobelco manual may give exact specs if you can get your hands on one) if there is a large amount the travel motor may be passing more oil than normal causing it to slow down! But chances are it is more likely the slew joint, yes that is it, you can acess it from underneath aswell as above, both if you need to remove it! theres no real way of checking it, although seal wont be very expensive so most poeple pull it out and reseal it, you may find a bad seal when doing this! Hope this is abit more understanding CPS
Before we get too carried away, lets start with the not so obvious but easiest to rectify! Ensure there is nothing obstructing the travel pedal (Of the one corresponding to the slower side) and limiting its stroke (trap for young players ). Next, check if the maximum pressure can be built up with other movements on the same control valve (Check the MRV pressure) - If the MRV pressure is down, even just a little, get it back to spec as this can have an adverse affect on other components and circuits. (This wont be the root cause). Now check if the movement of the travel circuit spool(s) on the control valve is ok. If the spool is ok (You can skip the last step and do this step 1st if you want, but if this step turns out to be ok then go back) check the pressure of the SRV and again, adjust as required (If there are 2 or more SRV's then the gauge will read the pressure of the one with the lowest setting) Check the condition of the ACV for the travel circuit (If the machine has them) If you find the above to be in spec or in serviceable condition then the probable faults are as follows: Rotary joint (Internal leakage) Hydraulic motor (Excessive wear between barrel/pistons casuing excessive leakage through the case drain) Travel brake (Not fully released, released but deformed lamellas caused by overheating) I think the above is pretty self explanitary to check and rectify, but before you go removing and resealing your rotary joint I would advise checking for leakage first. Quite simple really (If the test fittings are installed), you will need 4 test gauges (And corresponding test fittings and test hoses) Identify and A, B, C, and D ports on the rotary joint. Connect the four gauges to the travel circuit. Label the gauges as per the rotary joint labels, A, B, C, and D. Apply Left and right hand sides, both forward and reverse individually and recorded pressures. What you want is something like this: A 123 Bar B 0 Bar C 0 Bar D 0 Bar What you dont want: A 123 Bar B 123 Bar C 0 Bar D 60 Bar Let me know how you go!
Chris - Very helpful advice, thank you. I like the idea of getting some data before taking things apart. I just got this machine and in the middle of getting the engine back together after repairing some minor oil leaks. Should have that done over the next couple of days. I also just got the manual on it and have started working my way through the maintenance list and I am not so sure the most recent owner was particularly diligent. For starters, the hydraulic level is somewhere below the bottom of the sight glass and the swing motor level is below the bottom of the dipstick. Getting those trued up wont hurt things. When I was messing with the track issue noticed that the handle/pedal arrangement in the cab had a lot more side to side play on the problem side vs. the other side. To me, this did not look like it had anything to do with the actuation of those valves (front and back movement) but I am not an expert on how that valve box is built. I was considering switching the lines there and seeing if that did anything. More to come on this happy subject but it will be a few days until I am prepared to test out some theories. Finding pressure gauges for those 25 mm or so lines here in the US might be a challenge........ Bill
By all means, good thinking, very simple to do and something else to cross off the list. Its definitely not uncommon for the casting lands in control valves to hydraulically corrode causing pitted spools and/or casting lands which, in turn, will reduce the sealing of the valve. When the errosion reaches a critical size, a small orifice is created allowing oil under flow and pressure to bleed off from the pressure port to the tank port, and as such will result in poor performance (In your case, slower travel on one side than the other) Which brings me to my next question Is the side in question slower in both directions!? Remember, troubleshooting is generally used to describe noninvasive methods to determine the cause of a fault.
The travel speed is reduced in both directions and at both high and low speeds......
Whats the latest buddy?
i have been waiting for a gasket to get the engine going again. This machine was not well cared for before I bought it. When I went to change the oil, the oil drain plug was worn completely smooth. Shy of welding a bolt to it, there was no getting this off with conventional hand tools! So I dropped the oil pan and ordered a new plug and gasket. Will have this back together this weekend and will get back at this track issue Sunday - stay tuned! Bill
For next time (or for others), vice grips with good teeth or better yet, a hammer and metal working chisel; just tap it around on the angle - then replace the oil drain plug. Staying tuned. As my drive motors are getting slow too.
well vice grips was not getting it done on the machine. This baby was stripped and tight. What worked on the bench was heat, a pipe wrench and a pipe on the wrench. Then she came. Guess I could have tried all that on machine - next time!
Hi Chris5500, Hitachi excavator EX200-5,one side treak tread run faster so it will run to one side,If we repair it according to what you said on #5.What should we notice? Thank you very much
Hello caiwu, I'm not quite sure as to what you mean by "what should we notice?" If you care to explain as to what you mean, I can try and answer your question
I mean please help me to troubleshoot the problem of Hitachi like you do for Kobelco on#5.Is the pressure the same?Is the test procesure ithe same?I have no service manual. Thank you very much.
The procedure would be the same; it’s a generic one that can be used on any excavator to diagnose poor travel performance. The pressure's I used for the rotary joint leakage test "123" are just an example to show the desired results (no leakage between ports), regardless of pressure. If you followed the earlier steps then the pressure at the rotary joint should be within specification as you would have set the MRV pressure, which I'm guessing would be up around the 300 bar mark. You wont need a service manual to do the above, but you will need specs for the relief pressures and some test gauges. Hope this helps.
Chris, if I wanted to get some gauges to do some DIY work on the farm digger, dozer, bobcat, you know... what should I be buying? 1 or more and a working range pressure ??? Cheers.
I use a variety of different stauff test equipment with Caterpillar and Komatsu test adapters. Depending on what type of equipment you have whether it be Caterpillar or Komatsu, will determine what adaptors you need to buy to fit the machine. Probably your best bet would be to pay a visit to your local Pirtek branch and check out their range of stauff test equipment. I highly recommend the stauff brand, very good quality and compatibility. Off the top of my head I think the gauges are roughly $40-50.00 each for a gauge, regardless of pressure, and the test hoses are roughly $30-70.00 depending on the length you want. What you want: Stauff 63mm, stainless steel dual scale Bar/Psi glycerine filled, bottom entry test gauge. Stauff test hose 1/4" Bsp gauge connection x 16mm x 2mm ‘Test 20’ Female Swivel w/ Dust caps both Ends. For a general service set for the smaller equipment as you mentioned, you'd probably be only looking at one 400 bar gauge (for mains and secondary's) and a 60 bar gauge for pilot pressure. If you were really keen and thought it would be worthwhile you could get four 400 bar gauges for a rotary joint leakage test on your excavator. Hope this helps
Thanks bud, the main animal is a SH145 Sumitomo 1996 (13 ton class) which must stay alive ATM, as it has the most punch. It's due for service and has to track a 1km back to the 40 foot container (workshop). We try to spoil it when it comes in, even break out the MIG sometimes It's going to get new chains this time, so I might look at the slowness in the hydraulics also, yours & CPS tip's have been noted - thanks to both .
removing slew joint OK guys, still plugging away on my track speed problem. Today I finished getting the motor in shape - no leaks and purrs like a kitten so i am psyched about that. So then it was on to the track problem. Checked the motor on that side an no fluid comes out the drain line. So that does not seem to be the problem. Frankly I was considering living with it for a while but in evaluating the motor problem I have found a persistent leak at the top line of the slew joint which goes to that side but not enough to cause the problem. To really tighten this joint I found that you need to remove the two below it and by the time you have all three off you are rapidly draining most of the hydralic oil. I found out by accident that with the bottom line of the slew joint off you drain just about all of it.:Banghead SO here I am with the hydraulics drianed and 3 of the lines off the slew anyway. I am figuring now just take off the damn thing and take it apart and check that off the list. Anyone have any experience with the SK150 and how involved this is - basic steps, etc? Thanks - Bill
rotary joint Anyone have any experience dropping, inspecting and resealing the rotary joint on the kobelcos? thanks - bill
swivel joint There are only 5 gaskets (or slipper seals) and 3 o-rings in the swivel joint it is just a chromed cyl not a big deal to replace as long as the chrome is not scored up but I will tell you that we have had to rebuild very few of them the just don't seem to have many problems and we have hundreds of Kobelco's out at our dealer
dirthog your advice much appreciated. this machine only has 6000 hours on it so I am thinking I am going to go with the odds here and button this thing back up and save the joint rebuild for last resort. The lines have all been replaced in the past around the speed controls and one is much looser than the other so I think I will switch them and see what happens. You never know. Thanks
Would you mine having a look at your travel motors (if you still have the covers off) and see if your numbers are similar to mine from the link below, please. If I do end up having problems, it would be nice to know that there is something which might be interchangeable. Cheers.
Even side to side movement of the controls can be the cause of your problem . A worn bush causing the movement can cause the bell crank to skew sideways a little creating lost travel in the other plane . Also a tight track can cause it to be slower than the other .
Thanks for this advice. Will be my angle of attack this weekend. Stay tuned.
I have now switched the control hydraulics and the same track stays slow so the problem is not in the control valves. Also checked the tension on the tracks - no issue. I checked the motor before - nothing comes out the drain line, so no blow by. To me this leaves only the swing joint. Is there any other possibility? I am out of ideas other than the joint.
So you swapped the service lines at the control valves with no change? Try swapping the service lines at the travel motors, if the fault jumps from the right hand to the left hand travel motor it is the rotary joint, if it remains on the right hand side it is the motor.
What, nothing at all? not even a trickle? I got a steady trickle out of mine when I did the same test.
Nothing to worry about, its perfectly normal, thats what its there for.
before you go too far once you get the machine back together and operational there is one simple check you can do and it might cost a total of $7.00 in o-rings X 2 kits. i have sped read the topic discussions, with track issues the questions would be; 1 - does the machine track straight, or off to one side, and if so which side (referencing sprockets at the rear) 2 - when lifting the track off the ground is it slow in forward direction or reverse or both 3 - when tracks off the ground does the slow direction load down the engine? 4 - does the problem get worse as the hyd oil warms up? i suspect that the 3 o-rings located in the one end plate of your hyd pumps regulator block have gone hard and hyd oil is leaking past the one o-ring which holds the hyd pump swash from that one hyd pump rotating group to not destroke as far as it should. the check is quick and simple, open the pump door, staring at you on the outside pump "p2" that regulator end plate has two adjustments (which should not be adjusted), the one that sits untop a stacked nut affair has a small square screw held by a 13mm nut. scribe marking the orientation of the nut, sqaure, etc... loosen this nut allowing the square adj screw to turn with it. view inside the open hole and it should be dry, if oil drips out the o-rings require replacing. if unsure you can start and operate the machine to allow hyd oil to warm up, no oil should exit past. the hyd pump regulator on the pump closest to the engine is a mirrored version and the end plate faces the muffler. this one sees more heat and is likely the one leaking ph: 905-888-9070 ask for Adam. you do both regulators. at this point call me i'll explain as easier over the phone.
most older kawasaki hyd pumps have this issue come up when the o-rings harden usually occurs every 5000-6000 hours or so. the new kawasaki pumps used in todays machines eliminated this problem for the piston and adjust screw are machined as a one single piece now.
answers... Mr K - First, I have thrown up my hands on this one and have hired a local witch doctor to come have a look for 60 bucks an hour. He comes highly recommended so I will see what happens on 12/15 when he comes. In the meantime to answer your questions things run well just one track is slower and weaker than the other in both high and low speeds and forward and reverse. The main gear on the track seems fine - no grinding, jerking,etc. I do believe it gets worse when the oil warms up...... As I noted early, there is nothing that comes out of the drain line on the motor ( which the witch doctor thought strange over the phone). So here is the stupid question - is the hydaulic pump you are talking about the main one attached to the end of the engine? I will have a look and see if I can find the components you are referencing. For 7 bucks its worth one more shot before the witch doctor. Thanks - Bill
OIL COMES OUT THE FRONT SCREW IN COPIOUS AMOUNTS. Back one seems to seize up when its about 2/3 out but all the threads on the back are dry. SImple job to replace these O rings? Happen to know the kobelco part No. for the kit? Thanks - Bill
Progress Mr. Kobelco - Thanks for the help on the phone. Changed out the o rings on the front unit. Still need to inspect the back unit. O rings were certainly toast - dried and not working properly. Machine now seems to do OK in Reverse - still a difference in speed in forward. I ordered the exact rings from kobelco and when they show up I will change out the back as well. This looks like a PITA as its under the muffler and not easily accessable. However now that I know the routine (thanks to two phone calls) should be no sweat. Will see how the machine operates afterward. Going to use the machine for the day tomorrow and see what observations can be drawn.