Kobelco hydraulic excavators

[MR. KOBELCO]

Hi Gents, just starting to check hydraulic pressures on my SK130lc. According to Kobelco the traction motors need to be stalled and pressures measured at stall. In order to do this it looks like they offer a special tool which locks the sprocket but our local Mazer Group parts guys are not familiar with it. I think they`ve only been handling Kobelcos for a short while. Was wondering if this is something that most guys just fab up to hold the sprocket. Looks like the proper way to do it is to lock both sides at the same time. Don`t want to break anything! From the Kobelco test procedure sheet I could not really see what it looked like. Also I presume that by secondary pilot pressure they mean pilot pressure right at the (for example) swing control valve. Do you T into that pilot connection or dead end it to the gage or does it matter.

hi,
this tool is nothing special - just take an old say bucket pin of the diameter which will sit in the tooth groove of your sprocket and when moving forward direction it will jam against the frame stalling the travel motors. can even stall it in reverse by placing the stalling pin on the underside groove which will then jam in the upward rotation.
cut the pin to make your two pieces, weld a t-handle untop for safety, when placing and stalling do not stand right in front keep off to the side.
pressures read when stalling both travels simultaneously together, h-mode, wide open throttle.
as far as secondary pilot prs you'd have to tell me where this reference was made in the data.
cheers!

 

[rippy154]

Hi Gents, just starting to check hydraulic pressures on my SK130lc. According to Kobelco the traction motors need to be stalled and pressures measured at stall. In order to do this it looks like they offer a special tool which locks the sprocket but our local Mazer Group parts guys are not familiar with it. I think they`ve only been handling Kobelcos for a short while. Was wondering if this is something that most guys just fab up to hold the sprocket. Looks like the proper way to do it is to lock both sides at the same time. Don`t want to break anything! From the Kobelco test procedure sheet I could not really see what it looked like. Also I presume that by secondary pilot pressure they mean pilot pressure right at the (for example) swing control valve. Do you T into that pilot connection or dead end it to the gage or does it matter.

I usally stall the machine aginst something if I am by myself.....for example I have a large pile of steel road plates I walk the machine up slowly and wait for them to stall and then raise the idle.... I have also used a dozer blade, jersey barriers.....

I have no update with my machine since I have had my hands full with all the other breakdowns on a big ledge job. I am planning on getting it back in the shop soon so I hope I will be able to help you.

As far as testing pressure at you swing control valve you would T into it. If you are checking Secondary pilot at the pump you would T in as well

Is your 130 the same as mine??? Has no steeping motor or does it have metronics???

Take care

 

[rippy154]

If you are checking Secondary pilot at the pump you would T in as well Take care

I meant if you are checking negitive control pressure at the pump you also would T into the pilot line

 

[rippy154]

Hi Gents, just starting to check hydraulic pressures on my SK130lc. According to Kobelco the traction motors need to be stalled and pressures measured at stall. In order to do this it looks like they offer a special tool which locks the sprocket but our local Mazer Group parts guys are not familiar with it. I think they`ve only been handling Kobelcos for a short while. Was wondering if this is something that most guys just fab up to hold the sprocket. Looks like the proper way to do it is to lock both sides at the same time. Don`t want to break anything! From the Kobelco test procedure sheet I could not really see what it looked like. Also I presume that by secondary pilot pressure they mean pilot pressure right at the (for example) swing control valve. Do you T into that pilot connection or dead end it to the gage or does it matter.

Had a little time today to look at my 130 and had start over since I have been so busy with other stuff and couldn't really remeber what was going on. Not sure if this will help but here is what I have done so far and the results I have gotten


SK130 serial number YPU2412

The problem is "WEAK SWING"

The main problem is i'm having a hard time stayig on this one project becuase I'm the only mechanic so I keep starting and stoping my trouble shooting.

Anyway here I go


1) Tested pilot pressure had 810 psi (i know it is a little high and will set to 710 psi)

2) Tested Mains by stalling tracks and had 5100 psi spec calls for 4980-5050 psi (again a tad high and I will reset them)

3)Checked port reliefs (swing) by stalling bucket I had 1600 psi stalling to the left and 3800 psi stalling to the right (both below spec and I think they are adjustable with internal shims and for now continuing with tests) SWAPPING RELIEFS FROM LEFT TO RIGHT DID NOTHING ....PRESSURES STAYED THE SAME

4)Checked negitive pressure and had 400 psi spec calls for 455-668 psi ( again a little low and will reset)

5)Checked secondary pilot pressure at swing control valve had 200 psi swinging to left and 300 psi swinging to right

6) Did a swing motor drain test had 3.5 gallons in 1 minute while stalling swing to the left had less than a pint stalling swing to the right.... the spec calls for Standard 1.8 gallons per minute Maxium 5.3 gallons per minute ( not sure but seems odd to me to have some leakage one way but none the other??????)

7)Checked to see what the negitive pressure dropped to while stalling swing While stalling swing to the left it dropped from 400 psi to 380 psi... while stalling swing to the right it dropped from 400 psi to 220 psi

8)I decieded to swap the pilot lines at the swing control valve (port PA and PB) and checked the negitive pressure drop and it stayed the same While the swing stalled to the left the pressure dropped from 400 psi to 380 psi and while the swing stalled to the right it dropped from 400 to 240 psi

9) With the pilot lines still swapped (port PA and PB) I rechecked my port reliefs (swing) and noticed the problem switched sides at the relief valves with stalling the swing to the left was 3400psi and stalling the swing to the right was 1400 psi

So this is where I am at and I hope I am going in the right direction or at least it offers a little more insight for you...

Take care
Stephen (rippy154)

 

[rippy154]

6) Did a swing motor drain test had 3.5 gallons in 1 minute while stalling swing to the left had less than a pint stalling swing to the right.... the spec calls for Standard 1.8 gallons per minute Maxium 5.3 gallons per minute ( not sure but seems odd to me to have some leakage one way but none the other??????)

QUOTE]

FYI.... just looking in my other service manual and it says that 1.32 gallons per minute is the maxium in a case drain test and my other says 1.8 to 5.3 gallons per minute??????? I think 1.32 sounds more believable but hopefully I can find the correct information

 

[jey_c]

Interchange left and right relief valve and check again

 

[Kobe130]

Thanks Stephen (Rippy) your documentation is excellent. You are way ahead of me. Just picked up my RH joystick from the shop today. They resealed it and did not find any stuck or broken parts so now I am really worried. The boom was drifting down fast in neutral until I cut pilot pressure then it would hold like a rock. They tell me that possibly means a porous casting or an internal crack in the joystick case. Kobelco only offers a complete control not just the casing and its $1050 cahunas. Ouch. I won't get the resealed unit on for another week so I don't know if this problem is fixed but I'm expecting the worst. After that I will have to continue checking pressures so I can isolate the slow swing problem. I guess there is always a good reason people sell off used equipment. Anyway, one problem at a time and eventually they will get fixed. Meanwhile, the temptation to work on my new (to me) Crownline 225 is getting overpowering! Chiao

 

[Kobe130]

I went out to my machine today and installed the resealed RH joystick. To my great relief the boom holds when pilot pressure is on now. Apparently there must have been an internal leak which was corrected by the reseal job. The outside of the case was completely dry so this was a surprise. Probably a good idea to reseal both of them when one exhibits a serious problem - would have saved some time. Now on to the slow swing problem.

 

[rippy154]

Sorry its been awhile without an update but I had a tough week with all the rain we had here, the good was when I got back to the garage I walked over to the machine and said " I know I am losing pilot pressure so lets find out where"

The 1st thing I did was deadhead all my left hand pilot pressures at the main control valve. At Arm in ,Arm out and swing right I had 680 psi of secondary pilot pressure and at swing left I had 320 PSI.

I decieded to go right to the pilot control handle to ellimanate a bad hose ,restrictor or clogged screen

Result was the same coming right out of the handle. I disasemmbled the pilot control handle and at 1st glance everything looked fine and than I realized that for some reason one of the spring seats was in the wrong positon. 1 and 3 have differnet lenth spring seats than 2 and 4... put the parts back where they belong and now everything is working fine.

The only thing I can think of is one of my operators (sometimes the operators like to play mechanic and tell no one) or another mecahnic (the company had 1 other full time mechanic before the economy crash a few years ago now its just me) resealed the handle due to leaking and didn't realize that the seats differ

Anyway What a pain but it freshend me up on my troubleshooting skills

 

[rippy154]

I went out to my machine today and installed the resealed RH joystick. To my great relief the boom holds when pilot pressure is on now. Apparently there must have been an internal leak which was corrected by the reseal job. The outside of the case was completely dry so this was a surprise. Probably a good idea to reseal both of them when one exhibits a serious problem - would have saved some time. Now on to the slow swing problem.

Is your swing problem only to 1 side or is it just real slow in both directions????? Does the speed increase when you arm in while swinging?????

I always check pilot pressure 1st. Put a 1000psi gauge right on your pilot pump and you want around 710psi with warm oil around 775psi or close to 800psi with cold oil but always set pressure with warm oil

I would check your circuit (swing) reliefs by putting a 5000 psi (minium) gauge on pump 2 and stalling swing both right and left and than check your secondary pilot pressure right at the swing control valve using a 1000 psi. i wouls tee in to see your working pressure but also deadhead it to see what deadhead pressure is as well

You could also take the caps off the spool at the swing control valve to make sure the spool moves smootly by hand and that the spring is not broken.

You very well could have an internal leak in your left pilot handle as well but first you have to figure out what circuit your problem is in Primary Pilot, main or circuit reliefs, secondary pilot

Let me know if I can offer any other advice

 

[Kobe130]

Glad to hear it was as simple as that! The slow swing problem on my sk130 seems odd to me. When I throw it into swing on either side nothing happens for a second or two then it slowly begins to swing smoothly - no noise. If I pick up the boom it greatly increases in speed. Same going the other way. Does this sound like a broken spring in a pressure relief (or its jambed) where its given up and can not hold much pressure? I'll have to pull out all the relief valves to check them. Hopefully this is not a main pump issue.

 

[rippy154]

Glad to hear it was as simple as that! The slow swing problem on my sk130 seems odd to me. When I throw it into swing on either side nothing happens for a second or two then it slowly begins to swing smoothly - no noise. If I pick up the boom it greatly increases in speed. Same going the other way. Does this sound like a broken spring in a pressure relief (or its jambed) where its given up and can not hold much pressure? I'll have to pull out all the relief valves to check them. Hopefully this is not a main pump issue.

What swing control valve do you have??? There should be a tag right on it.

Swing is a 1 pump function using only pump 2 which is the pump furthest from the engine. If you really feel you have a pump problem you can swap the 2 feed hoses off your pumps which would switch your swing to run off pump 1. If it worked better you could assume that pump 2 is bad... however pumps rebuilding is very very expensive so you will want to be sure. I have seen regulators go bad but usually you will have two functions go bad at the same time that run on the same pump

Do your pressure tests tell will tell you a lot. I'm not sure how many machines you have but you don't need to buy a bunch of gauges get 2 6000 psi gauges and you can do all your tests. You will also need a few adaptors and T's.

When I was talking about a spring I was talking of the spring on the spool in your swing control valve. The spool is held in a neutral position by spring pressure and when secondary pilot pressure enters either Port Pa or PB it will overcome the spring pressure swinging the machine left or right. Sometimes the spool can get hung up and not slide real smooth.. Its rare but real easy to check.

Where do you live????

Do you have a service manual???? If not I could copy some pages out of mine and mail or fax or scan and emil them

The test are easy you just need some time and if possible lots of beer Sometimes I wish i could drink at work LOL

Anyway let me know if you need anything

 

[Kobe130]

Thx, Rippy. My limitation is time - just not enough of it. I have the Kobelco service manual for this machine - it is a must for doing this kind of trouble shooting. I see guys commenting in these pages all the time about not having one. The simple answer is ya gotta spend the 250 bucks and get one. We're up in Manitoba about an hour's flight north of Minneapolis. The Kobelco brand is just inching its way up here the last few years. Seems to be mainly Cat country. Have some high pressure gages now just need to get some Ts. Think I will start to check the relief valves tho as that seems the easiest thing to start with and I'd like to reseal 'em and check for breakage anyway. I'm not a HD mechanic by trade but this machine and my 580s are turning me into one. Regarding the pumps I hear awful numbers like $5000 get thrown around to rebuild one so I'll make sure it really needs it before I go that route. There are Chinese made internals for these main Kawasakis - wonder how they compare to the originals? At any rate I will track down the swing issue and now I know its not the same joystick problem you had. Cheers.

 

[Kobe130]

To answer your questions, machine is 1998 sk130lc, serial YPU2328. Stepping motor removed by me, replaced with straight cable throttle. Only pressure measured at this point is pilot at the gear pump read about 700 psi. Travel seems good, boom, arm functions are good. Main problem now seems to be very slow swing although it does operate in both directions. Eventually I will measure all pressures and readjust to spec. Both LH and RH joysticks have now been disassembled and resealed. Both boom cylds leak at the gland so off they come this winter. With all these hydraulic troubles I take some comfort in that the previous owner put a reman 4BT in it only 2 years before I bought it. Purrs like a kitty. Yep, it was so hot this summer I went thru plenty of cool ones while cussing at the thing.

 

[StumpyWally]

New Holland EH 80 (Kobelco) 2005

Bought this machine used in 2008 with only 615 hrs. Steel tracks, short arm 5'-11", Isuzu engine, excavator s/n N5TA18019, with Geith hydraulic thumb & 24" Werk-Brau bucket.

Have 2 problems:
1. Travel alarm does not work, never has, but fuse is OK. Is it the alarm itself, or some relay or sensor??

2. Bucket cylinder does not hold position when control is in neutral, bucket drops very slowly. There are no external hydraulic leaks. Is it the cylinder (so a repack may help), or the control valve?? Where is the control valve??

Otherwise it is a great machine & I love it!!

 

[Trinhvo]

Hi Mr Kobelco and everybody, i have some trouble about the engine and the hydraulic system with my Kobelco K904c excavator, so i really need a shop manual of my excavator, please help me!

 

[MR. KOBELCO]

Hi Mr Kobelco and everybody, i have some trouble about the engine and the hydraulic system with my Kobelco K904c excavator, so i really need a shop manual of my excavator, please help me!

hi,
please provide the serial number of machine and which may help out the engine make, model and eng serial number too.
adam

 

[MR. KOBELCO]

Bought this machine used in 2008 with only 615 hrs. Steel tracks, short arm 5'-11", Isuzu engine, excavator s/n N5TA18019, with Geith hydraulic thumb & 24" Werk-Brau bucket.

Have 2 problems:
1. Travel alarm does not work, never has, but fuse is OK. Is it the alarm itself, or some relay or sensor??

2. Bucket cylinder does not hold position when control is in neutral, bucket drops very slowly. There are no external hydraulic leaks. Is it the cylinder (so a repack may help), or the control valve?? Where is the control valve??

Otherwise it is a great machine & I love it!!

hi,
1- travel alarm failure is common, likely just needs to be replaced.
2- bucket cyl, does the bucket rod extend? that is bckt dig motion? when you lift the lever lock does it stop moving?
have you checked the hyd cyl for bypassing past the piston internally ?
adam

 

[StumpyWally]

hi,
1- travel alarm failure is common, likely just needs to be replaced.
2- bucket cyl, does the bucket rod extend? that is bckt dig motion? when you lift the lever lock does it stop moving?
have you checked the hyd cyl for bypassing past the piston internally ?
adam

Thanks for travel alarm suggestion.

Bucket cylinder works & digs fine. What do you mean by "when you lift the lever lock"?? The machine has full pilot controls, so the bucket cylinder is operated by moving the right-hand joystick left or right.

As for checking if the piston cylinder is being bypassed internally in the cylinder, that's what I suspect is happening, but how do I check for that??

Also, I forget in my 1st post, but I have the same problem with the hydraulic cylinder on the Geith hydraulic thumb. It works fine, but when the thumb is not being used, or the machine is off, the hydraulic cylinder position creeps & allows the thumb to very slowly fall from its fully retracted position. So that I have to periodically fully retract it again by pressing the top right button on the right hand joystick. Same question on how do I check that cylinder for internal piston bypass leakage??

Tom

 

[Trinhvo]

hi,
please provide the serial number of machine and which may help out the engine make, model and eng serial number too.
adam

ok, the model is K904C, serial number is k-14354, the engine is Mitshubishi 6D14C.