I have an 89 Hitachi ex60URG - there is a lack of power in the track motors. My center joint is not visibly leaking hydraulic fluid but can they leak internally? Or maybe the track motors are bad. One is slightly slower than the other. Is there any easy way to tell whether it is the center joint or track motors?
Need more info. "One track is slightly slower..." I assume you mean while tracking. Is that track slower than the other in fwd and rev? How well does the machine turn from sitting still (not turning while tracking)? Is the same track still weaker than the other in both directions? Do both tracks labor to turn the machine from sitting still?
Yes the track motor seems to be slower in both directions while tracking and yes the machine has a GREAT difficulty turning from sitting still. Is the same track still weaker than the other in both directions? -- I think but would have to check to be sure.
There's still a number of things that can cause this, but given what you've said, I'd check the case drain on the motors. You'll have two large fittings connected to each motor, and one small fitting connection. The small one is the case drain. The case drain is for draining off normal leakage inside the motor, but it should only be a small amount of oil while motor is operating. Excessive leakage from the case drain could indicate motor with worn/bad internal components, which would cause a weak motor. I think the EX60 has a blade. If so, lift one end off the ground with the blade. Spin the machine around. Lift the other end off the ground so you can work tracks and not move. Remove the case drain line from a motor. You'll need a plug for the hyd line. And it would be great to have some kind of hose to connect to the fitting on the motor so you can run the hose to a bucket. Operate the motor and monitor how much oil comes out of the case drain in a minute. Repeat the process on the other motor. If one motor has a considerable amount more of oil filling the bucket in a minute, it's likely that it's a bad motor. And you should do this with the machine and oil warmed up. It would be really good if you could do this while the machine is tracking under load, that's a little more difficult to do though. Try this out and post back the results and we'll go from there.
Okay thanks for your help. I will try to do this this week sometime.
Case drain is the basic check with the motor stalled you should get but a few ounces in 15 sec there is a spec for it some were if you get a gallion its a bad motor but double check the max spec. and yes the swival joint can and does leak inturnaly that is a mutch cheaper fix so dont over look it. there also can depending on the machine be other suspects strait travel valves pilot psi problems switches theat stroke the pumps in differant functions but start at the case drain.
Today I ran the machine for a while to warm it up -- lifted tacks off ground and tested case drain from the motors. L side was 250ml (8.5 ounces) in one minute. R side was 2 L (1/2 gallon) in one minute -- This obviously was the motor that had a lack of power. I imagine that motor needs to be rebuilt? What are the chances of a new seal kit fixing it? Thanks again.
Well it does appear that there's a difference between the motors. At this point, I would really try to find out what the leakage spec is on the motors if possible. If it turns out to be bad, it's unlikely a simple seal kit will repair it. Most excavators use axil piston motors. Excessive internal leakage via case drain is usually worn internal components like wear between end plate and piston chamber, disassembly of the motor will usually reveal the failure.
Ill bet 1/2 gallon is not out of spec a seal kit would only fix external leaks.I never realy worked on that small of machine but max is probly closer to a gallon.
I found a spec for it -- looks like "allowable limit" for an ex60 is 2 liters or 0.53 Gallons when raised of the ground and 4.3 liters or 1.1 gallons "at relief pressure". What does at relief pressure mean?
At relief pressure would occur when you are applying full power (pressure) to the motor. Like when you lock the track up and it won't turn.
Doesn't sound like your too far from spec, sounds like it's something other than motor. One thing you always want to check is the pilot valves at the drive levers. Make sure they're not fowled up with dirt preventing full movement of levers which would limit drive control. If everything is good there, I believe I would go after the rotary joint next. Yes, there are other things that can cause this problem as well, but if the machine has some age on it, chances are the swivel seals are aged as well. It's not a hard component to repair, not terribly expensive, and even if it's not your problem, it's one more component on your machine that you have in good order.
I Looked at the pilot valves at the drive levers -- everything okay there -- looks like everything is getting full movement. So I'll order a seal kit for the center joint and see what happens.
Center joint is easy to reseal its just an oil mess to get out i used to dig a hole out in the field so i could stand under it and step out of the way when the oil flows depending on the machine maybe on that you can do it from the top mark all your hoses good. and make sure the joint gets back in the same index as it came out.
We just resealed our center joint on our ex60 this past week. Just alittle oily coming out!
my UH 07-5 has similar issues done all the above centre joint seals and pressues and the centre distributor seals at the track motors but still not resolved i will now have to pull out the motor assemblies and check the seal/ replace the seals there , when i did the main center joint all the orings and packers were good we fitted new anyway , one set of the distributors at the motors were damaged , we thought we found the problem , but no still there having to go deeper in dos any one no what type of piston motor was used in the uh07-5 learning a lot about excavators only had mine 7 months cost quite a few dollars so far cheers
I had a similar problem with my newly acquired 1998 Yanmar (12,000 lb mini). Reverse was weak and one track stronger than the other. After a couple of weeks, I took off the floorboards and voila! the previous owner didn't have the linkages set up properly. Now I can run up and down hills, and even back up the ramp to load on a trailer. Did you check your linkages?
Yes I did check them... they were okay. I am still planning on doing the center joint - got the seal kit... now just waiting for some time to do it.
Ok, I just took a stab at it. Good luck on your rebuild. Hope you have some room to swing the wrenches. Mine would be a bugger! Ooops! I guess I should have said I just joined this forum. I'm a bit nervous, but I've been reading a lot before I joined in. I think I can learn a lot and perhaps contribute too. Cheers..
You may just want to recheck your leakage again under load as Bigstevex4 has suggested with that amount of variation from the left to the right I would take a closer look at the motors first, easy way to do this is insert a solid bar into the sprocket segment as you slowly rotate and lock it against the track frame in each direction, this will give you a try indication of the motor condition. With travel motors or hydraulics te thing to remember is flow makes it go, but pressure makes it go hard!
Sound to me like a centre joint seal. I have workek on lots of hitachi excavators and it seems that the centre joint seals are only good for 5000-6000 hours. From what you are saying 1/2 a gallon isnt really a lot of oil to leak off in one minute.
Panorama, Did you ever figure out what your issue was?
I did buy a center joint kit for it but have not put it in yet -- I am building a house so have not had any extra time. I will post a reply when I try the new kit.
I have a EX50URG and I resealed the centre joint, the job is much easier to do with open ended crows foot spanners, three eighth drive with very long extensions will do the trick to get down behind the main boom and undo hose connections. The hub comes out from the bottom of the machine, you have to remove the bash plate to get to the mounting bolts and steel lines. The tang that locates and locks the top part of the hub to the body has to be in the same position as removed from the machine, if not it is very very difficult to turn after the new seals are installed and the hub assembled BUT with a bit of thought and safety precautions it can be turned to the original location to bolt the tang on. Don't forget to mark the hoses that you take off with different coloured cable ties to the corresponding connections, makes life so much easier when it comes to fit the hoses back on. Goodluck.