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danc
04-20-2009, 04:58 PM
Hi all

I have a Hitachi ex-120-1, this is my 1st excavator and I use it for works around my own property.
I don’t have an operators manual, so real greenhorn, so bear with me if questions seem silly.!!.:)

I am building a house at the movement so with little spare time I try and squeeze in some repairs to the 120. I have only spent a few hundred hours in this machine, and the problem with the track motors, is there since I bought it, and got no worse.


When I lift up and spin the tracks mid-air, one side is much faster than the other, and during tracking, there is a turn to one side,
I am expecting work case the slower motor is dying., but id’ like to rule out that I’m not running a hare on one motor, a tortoise on the other first.


The hare and tortoise modes, fast/slow,are these only for track speed, and what does this switch activate on/off, is it related to solenoids on the track motor pilot controls??

The switch does turn the green indicator on the dash panel, on/off, but there is no change in speed, to either motor, so what should this switch be activating, relay/solenod etc..

willie59
04-20-2009, 10:35 PM
I'm not familiar at all with the dash 1 series of the EX120, I'll put that out right up front. It seems you have two problems. 1) motors tracking at different speeds, and 2) hi/lo speed not working. Let's say, your left drive is slower than your right drive, going forward. Is it the same going reverse, left slower than right? Secondly, I'm going to take a guess that the hi/low drive of the motors is done by changing the angle of the swash plate at the motors. If this is the case, you should have 4 hoses connecting each drive motor; 2 large lines for drive, 1 small line for hi/low speed change, and 1 small line for case drain. Update us on these tidbits of info and we'll try to take it from there and see if someone can help you out. ;)

cderekbower
04-21-2009, 04:55 AM
I'm not familiar at all with the dash 1 series of the EX120, I'll put that out right up front. It seems you have two problems. 1) motors tracking at different speeds, and 2) hi/lo speed not working. Let's say, your left drive is slower than your right drive, going forward. Is it the same going reverse, left slower than right? Secondly, I'm going to take a guess that the hi/low drive of the motors is done by changing the angle of the swash plate at the motors. If this is the case, you should have 4 hoses connecting each drive motor; 2 large lines for drive, 1 small line for hi/low speed change, and 1 small line for case drain. Update us on these tidbits of info and we'll try to take it from there and see if someone can help you out. ;)

very kind of you to help the man out. some nice guys on these forums.

danc
04-21-2009, 01:25 PM
some good folk on here alright, :)
Thanks for the input atcoequip...


Some futher detail Ö

The one motor is always slower both directions, there is a real obvious difference in speed, you donít have to count sprocket rpms, itís very clear., Iíd say one is at least twice as fast as the other.
This is in either direction, and the same speed achieved by fast and slow motor in either direction, if you know what I mean, a constant difference.



From below the area around the swivel joint was all oily and wet, with oil drips, so I said Iíd tackle this first.

I removed, stripped, resealed, and refitted the swivel joint, itís now bone dry around this area, no drips.

The one motor is still slow.


The plumbing to the motors is as follows, from the swivel joint:

2 pipes per side to each motor., forward, reverse. Then a common pipe from the bottom plate of the swivel joint, is Teeíed of to each motor (return?)
So 3 pipes per motor.

Without checking pressures I know this is a tough one, but any ideas welcome.

cps
04-21-2009, 02:04 PM
Hi danc, Where abouts you based at?

It sounds like the small pipe is the leak return from the motors! although some have 2 small pipes one for the brake! Not sure how hitachi works!

If the small pipe is the leak return take it it of have someone move the track and see if a good bit of oil comes out of it!

Or it may be that you could have nipped a seal when you rebuild it the slew joint!

danc
04-21-2009, 03:24 PM
yes the smaller pipe seems to be a return, it goes from each motor to a T just before it connects to the bottom of the swivel joint.

then 2 larger pipes to each motor.

I don't know what a flow from the small pipe will tell me if i can't be sure of what flow is going in, through the larger pipes.

would a large flow from the return indicate fluid passing motor seals or similar?

as far as a nipped swivel joint seal goes....the behaviour is just the same as prior to rebuilding the swivel joint, only no leakage from the joint now, so i'm hoping the joint is good, for now.

based in donegal...:)

cps
04-21-2009, 05:09 PM
Yea a high flow would indicate trouble with your motor! seals or worse maybe (hopefully not) , there should be no more than a dripple if its ok!

Im from Near Cookstown in Tyrone, was up in the Downings Easter weekend!

AtlasRob
04-21-2009, 05:18 PM
I'm not familiar at all with the dash 1 series of the EX120, I'll put that out right up front.

Neither am I, but I have learned something :D :drinkup


Yea a high flow would indicate trouble with your motor! seals or worse maybe (hopefully not) , there should be no more than a dripple if its ok!


Thanks cps, I did not know that. :notworthy

danc
04-21-2009, 05:46 PM
so if i lift one side up , get the track turning at low engine rpms, with the pipe open, I should have only a dribble on the good motor.

So where does the 'working' fluid go creating the rotation, back through the other direction pipe?

so the 2 main pipes serve as supply and return, when reversed, the travel changes direction?

I had it in my head that one main pipe for forward, other for back, with the small pipe as return to tank, after the fluid has done its 'work'

I'll try it on the fast one first in case i get a flood from the other :D
thanks for the tip..

I'll check it out ...

Cmark
04-21-2009, 06:21 PM
The flow is in a "loop". In through one hose, through the motor and out the other. This then reverses for the opposite direction. The small hose is a "case drain". It takes any internal leakage from the motor and sends it back to tank. It can be a rough indicator of motor condition. Large amounts of oil from the case drain = high internal leakage = not good.

However....

For your problem I would be looking at a pump flow issue. I am not at all familliar with your model, but I would guess that like most smaller HEX's there are two main work pumps. Generally, one pump supplies oil to the swing, dipper and one track. The other supplies boom, bucket and t'other track.

So...

I would suggest study the speed of the cylinders. At full rpm, compare the speed of cylinders controlled by the right joystick to those controlled by the left - any difference? Run each track in turn and operate a cylinder - any difference?

Can you post a photo of the pumps? I worked on an old Hitachi a long time ago and, from memory, each pump had a lever on the side to control the flow when an implement was operated.

Hope this helps.....

danc
04-21-2009, 06:34 PM
the pipework to the motor makes sense now, :) the case drain similar to an engine crankcase breather somewhat..


I'll hopefully have her back together for the weekend for the pumps test you mention, good info... I'm changing some bottom rollers as well so some more bits to be fitted before a test drive..

My first excavator to drive and own so nothing to comapre to really, but I will do the trials mentioned, and post some pump pics too.

cps
04-21-2009, 08:15 PM
The flow is in a "loop". In through one hose, through the motor and out the other. This then reverses for the opposite direction. The small hose is a "case drain". It takes any internal leakage from the motor and sends it back to tank. It can be a rough indicator of motor condition. Large amounts of oil from the case drain = high internal leakage = not good.

However....

For your problem I would be looking at a pump flow issue. I am not at all familliar with your model, but I would guess that like most smaller HEX's there are two main work pumps. Generally, one pump supplies oil to the swing, dipper and one track. The other supplies boom, bucket and t'other track.

So...

I would suggest study the speed of the cylinders. At full rpm, compare the speed of cylinders controlled by the right joystick to those controlled by the left - any difference? Run each track in turn and operate a cylinder - any difference?

Can you post a photo of the pumps? I worked on an old Hitachi a long time ago and, from memory, each pump had a lever on the side to control the flow when an implement was operated.

Hope this helps.....

To the best of my knowledge The ex120-1 have a single pump!

lgp
04-21-2009, 08:50 PM
I spent a lot of hours on an EX100 -1 back in the late eighties/early nineties. That machine had two pumps. One for slew motor, dipper ram, and one track motor, the other for main lift rams, bucket ram and the other track motor. The travel speed switch on the dash (hare/tortoise) operated through a microcomputer and electro-magnetic valve along with the working mode and auto-idle switches, and appeared to govern the engine revs downwards on the "tortoise" setting for a slower travel speed. I never operated an EX120, but I would think it would be similar in layout.

willie59
04-21-2009, 08:55 PM
Wow, you guys are all over this one before I could get back in here, rock on! :D I agree with checking the case drain on the slow motor. And if you only have 3 hoses at the motor, then the motor is fixed displacement and the speed change has to be done upstairs. I still leaning to that being a different problem, but we to do some testing on the slow motor first. The EX120-2 uses a single hydrostat pump, don't know if the dash 1 is the same. ;)

danc
04-22-2009, 03:45 PM
will hopefully get to do some tests over the weekend. took a few quick snaps before I headed to work.

motor had years of crap caked in behind the covers, a good clean up and paint required after i try and get things working better

willie59
04-22-2009, 08:53 PM
Whoa, that does look like a double pump, although I can't say I've seen one quite like that one before.

John C.
04-22-2009, 10:57 PM
Single speed motors and a double pump. As I recall those machines change travel speed by changing engine speed.

I have resealed about a half dozen swivels in EX200s. My first guess as to your problem would be that.

I didn't see in your posts if any other functions were slow. If you run a boom up cycle time it will pretty well tell you if your pumps are OK. Stretch the stick all the way out and put the bucket in the fully dumped position. Set it all on the ground, max out your engine speed and put in the fastest mode. Use a stop watch and time lifting the boom from the ground till it tops out. That should be around four seconds. It can run as high as five seconds and you will still be OK. If it's real slow then you could have a pump problem. Otherwise I'd pull that swivel apart first and reseal it.

Good Luck!

danc
04-23-2009, 01:32 PM
Hey John, I’ll do a timed run on the boom, do you mean a boom lift while traveling or stationary?


The area around the swivel was wet, and I was hoping after resealing that the slow motor would have improved.
Anyway it’s not leaking around the swivel now, so I’m looking at other possibilities.

The fast/slow speed not working is obvious now after some studying of the plumbing, there is a bank of solenoids next to the pilot filter,that have been unplugged, one of these leads to the injector pump, so looks like these guys are controlling the fast/slow via engine speed alright.

Went to try a few response tests today, but the faster motor sprung a leak in the casing, at the centre of the casing where the hex bungs are for the frinal drive filler, level.

A square plate has been welded to this casing, not sure why, but the weld has sprung a leak, so must fix this first. Some day I’ll get there….

danc
04-23-2009, 09:12 PM
Well things are not looking good on the fast motor now after it sprung a leak today

There was some dampness around where the blue line is for a while, and it was on my to-do list, but today when trying to troubleshooting the slow motor issue, the good side goes bad.

today a 4-5ft hydraulic leak came from the weld around the plate on the outer cover.
Iíve never seen inside one of these final drives, and trying to visualize how it works internally. I am thinking there should only be gear oil, and not hydraulic fluid in this part of the drive?
I didnít get to removing the hex bungs, but I think this is now full of hydraulic fluid. I stopped the engine within a few seconds as I was looking down in that area at the time.
If this is a seal problem, is it common, and can it be resealed without special tools?

John C.
04-23-2009, 09:20 PM
Seeing your photos and hearing your description I'd say the drive motor is shot. Your are correct that there should be gear oil in the sprocket side of the drive.

Basically you have to split the track and roll it off the final. Mark the relation of the hose connections on the motor with the track frame for when you reinstall the unit. Take out the ring of bolts that holds it in and you will need something to lift it clear.

I don't know what the parts situation is on those units these days but Hitachi was always pretty good for carrying them. I'm afraid you are going to find that there isn't much left inside that motor but shavings.

Good Luck!

danc
04-23-2009, 09:52 PM
and that is the drive with motor that was fast,

the initial issue was with the slow speed to the other side....



it was very smooth in operation , from what i could tell just prior to the leak, so fingers crossed, it's not as swarf

willie59
04-23-2009, 10:11 PM
Swarf??? Now I have an Irish lineage, but I hail from the hills of East Tennesssee. Please enlighten me on "Swarf". :)

danc
04-24-2009, 10:59 AM
sorry meant to say .. hopefully it's not all swarf...:D

swarf aka.. shavings... the debris that results from metals having a fight...:)


I figured in my head that there must be some seal set that keeps the hyraulics from the gearset, and the gear oil. maybe similar to the centre joint..

when this medium is breached are things so bad, that something metalic has worn beyond repair, or can this seal set just wear out.

Or is it always catastrophic failure.. game over.:confused:

cps
04-24-2009, 05:03 PM
Hi danc You may just be ok! It looks to me like it has blew the output seal on the motor just! This seal is around the output shaft of the motor, this in turn will fill the final drive will hyd oil and pressurise it untill some thing gives like the seals!! I have seen this happen and the motor and drive were ok!
You will still need to remove the complete unit from the side frame to seal it! Or at least this will be the easy way!

I hope I am Right and the motor is ok!

cps
04-24-2009, 05:25 PM
39662

39663
Got these from the Johndeere website (this relates to my tread Deere v's Hitachi) Johndeere and hitachi are the mostly same digger! They likely wont be the exact same as yours but it'll give you an idea as to what is in there!

willie59
04-24-2009, 08:52 PM
swarf aka.. shavings... the debris that results from metals having a fight...:)


I see, I too have seen the swarf that resulted from heavy metal prize fights! :D

danc
04-27-2009, 12:22 PM
cps, many thanks for the drawing, it makes sense now...

I have been told the seal kit is around Ä200,

So I need to tackle this before I get back to the other motor!

danc
05-06-2009, 05:00 AM
Well I have the final drive complete assembly removed and ready to strip it down..

The hydraulic lines to the travel motor were really tight and difficult to loosen.

Took the cover off the gearcase, and no metal or signs of any swarf.

Anyone got any pointers as to which side to tackle this from. I seems like stripping it from the motor side would be the way to go. No manual unfortunately

danc
05-07-2009, 10:43 AM
Well I got it pulled apart. CPS was correct looks like the motor output seal has blown.

I donít know if this is a result of something else failing inside the motor . Or if this seal failing just happens due to wear. If I change it will it be ok for many hours to come, or has something else made the seal blow.
Iíll try and tear the motor down for a closer look maybe

finaldrive
05-13-2009, 10:41 PM
Unfortunately this is a very common problem with the EX120 and 490D machines. The gearbox is built well but the motor shaft seals always fail.
I suggest contacting Plant Parts in the UK. There's no one I know that knows more about travel motors than them.
This particular motor is pretty simple to reseal, but you will more than likely find that your pistons and valve plate are going to be heavily worn. In my experience, if you don't replace the wear parts while you have it apart, you will always have excessive case drain.
Thank goodness you shut it down immediately. Otherwise the high pressure hydraulic oil would've destroyed the gearbox.

ncbschzzt
05-14-2009, 01:08 AM
ohh yeah this brings back some memories

danc
05-14-2009, 07:51 AM
I dismantled the motor to see if I could see another reason for the seal failing. I donít want to put it back with new seal to find it blows out again. Or maybe they just go over tiem, the output shaft is nice and smooth, no grooves

I have the motor apart and the pistons look good to me, but Iíve nothing to compare to.

Anyone got a photo of worn piston. How do they wear, does a ridge , lip, or groove form, or should they be checked by vernier, laser mic etc..?

I am waiting for brake seals to come, now I have it apart.

This motor was fast, the other side is the slow one.

ncbschzzt
05-14-2009, 09:42 AM
Did you check case drain pressure before you disassembled? Blowing this seal is almost always caused by excessive case drain. You are going need to either have to replace the motor or rebuild it. Pretty cut and dry solution for this type of failure. I will look up some prices for you.

finaldrive
05-14-2009, 10:34 AM
The depth of the oil groove on the piston will tell you how worn it is.
I have a workshop full of worn parts from cores, I'll try and post some photos later.

ncbschzzt
05-14-2009, 12:39 PM
usually you don't even need to look at the pistons, you can look at the valve plate and right away know its time. Any scoring, cracks or warping will tell you all you need to know. If your valve plate is damaged don't even waste your time, rebuild or replace the motor. Rebuild means all seals, orings, valve plate, rotating group, friction plates, bearings. If shaft is damaged it might be more cost effective to replace with a Reman component. You will find that many hydraulic repair shops will want to try and repair a motor with a damaged shaft and get labor hours. When actually it would be more advantagoues to simply replace, so beware of your the motor shaft as well.

finaldrive
05-14-2009, 12:51 PM
If the pistons are within serviceable limits you can lap the swash plate, pistons and valve plate and have it perform very good.
This motor is longer made by Uchida for Deere. Maybe ncbschzzt can tell us if they are even available Reman. Last I looked there were none in the Reman program. When they were, they were over $6000.00
Hopefully he can provide better news on price and availability than that.

ncbschzzt
05-14-2009, 04:51 PM
Sure you can lap the swash plate etc... However if the valve plate is cracked or damaged then its a waste of time. Usually are out of wear tolerances as I am expecting you already know. I couldn't count how many machines I have been to where the motor/pump was repaired and now the component experienced a catastrophic failure. Then the customer spends another few thousand on clean up and checking other components for contamination.
There are of course exceptions and I know machines are out there that have made it through. Many have been sold at auctions and moved on to guys like "danc" and now they are having problems. Countless auction machines have repaired hydraulic components and usually fail in the next 500 hours give or take of course. That isn't stamped in stone like I said, but it is a generalized statement in my experience with Deere/Hitachi excavators.
If the motor or its components are no longer available, then it wouldn't matter either way. I haven't had a chance to look yet, but if you want since you seem to already know the part number of his motor send it to me. Just because Reman doesn't have it doesn't mean its not available somewhere else. Could be a used one out there also, that is an option as well.

finaldrive
05-14-2009, 08:36 PM
TH111936 is the part number for the gearbox.
TH111937 is the part number for the travel motor.

ncbschzzt
05-14-2009, 11:24 PM
TH111936 is the part number for the gearbox.
TH111937 is the part number for the travel motor.

Where did you get that number from, an old parts catalog? Its subs like 6 times, I will have to research it tomorrow.

finaldrive
05-15-2009, 01:46 AM
Top of my head..I have a really good memory with part numbers. What's the subs? I'll memorize those too..haha

danc
05-15-2009, 07:49 AM
Thanks for the input guys. Iíll get another look when Iím home.

Just a quick recap, I have 1 slow and 1 fast motor ( the one that blew the output seal, is the fast one)

I had some leakage around the swivel joint, so I resealed this, leaks fixed now.
I did an airborne track speed test on each side, to find same motor still slow.

Moved the machine a few meters, then the leak sprung from the planetary gearbox, on the slow side.
The shaft that leaves the track motor, through the gearbox, is seated in place by a spud on the gearbox cover, I assume to control thrust, this had been reworked at some point, and the spud was welded in place. Lucky for me there was a weak point in the repair to the gearbox cover plate, and from a small hole in the cover a leak shot out. This leak happened when moving the machine as mentioned above.

So I have pulled the entire unit off,

I didnít get to do a case drain check, I was about to, until the seal failed



The drains on both motors are tee-ed before the swivel joint, is there a possibility that the other side could be causing over pressurization of the opposite side, or is this not possible.


Finaldrive
Some worn piston photos would be great, maybe some of a worn valve plate also.

I donít think I have a swash plate, piston ball assemblies acts direct on the sockets machined into the output shaft cupped area . ( wouldn't there be a another piped line to control swash?)
I'm not well up on the names of all componets, ( but something tells me I will be soon :D)


Iíll have a closer look at all components over the weekend

junior3434
06-08-2009, 06:35 PM
I have worked on quite a few of these machines...you seem to have tried all the usual solutions. i did have one that had a lot of muck around the track levers which made one track slower than the other....i know that sounds obvious but ive seen it happen.... failing that and with the other things you have tried....it would seem you may have one of the pumps not putting out enough flow...if you swap over the 2 pressure pipes on the main hydraulic pump(you will have to make a hose to do this)then swap over the 2 small hoses on the top of the pump, then start the machine,try out the speed of each track and if the opposite track is now slow then it will be your pump

ltafta
06-12-2009, 02:13 AM
If the link from stick to valve is mechanical check that the actuation of the valve is equal for each side. My Kubota suffered the same problem after I completed the reconstruction and it took me some time playing with the linkages to balance the actuation of ecah control to actuation of the valve.

danc
06-16-2009, 02:01 PM
Well Iíve been sick for a while, so just getting back to this again. My last post bit misleading, the output seal failed on the fast motor, sorry if I mislead anyone.

I fitted new brake seals when I had the motor dismantled, new output oil seal.

The pistons, valve plate and all components looked good to me, but Iím no expert.

I got a new spud welded to the planetary box cover to control thrust on the shaft from the motor. I have it refitted to the machine, and will be trying it again soon hopefully,
so back to trying to sort why the other motor is slow, I have some more stuff I can try thanks guys.


I have a slight suspension as to what the problem is, but I wonít say until I check it out first ;)

MrKomatsu
06-16-2009, 05:20 PM
case drain is 5gal. per min.....on motor..ex120

jetta125
06-17-2009, 09:54 PM
hi, i,ve been running a 120-1 for a few years now,if you hav a slow track chances are your problem is in the final drive gearbox bearings and or gears, that spud you had welded is just a guide and there should,nt be any thrust or force on it ,wear in there cause centre shaft to run out against cover and wear it ,thats prob why it welded up in the first place,As for your question about hi-low switch it only lowers engine rev,s on a 120-1, so cant cause any prob,

wstan01
06-18-2009, 05:16 PM
Hello guys-- Newbie to the forum!!! can anyone tell me if the serial #s are stamped into the frame on a grey market machine? I am parting one out and some genious removed the data tag. It is a Hitachi 120 Thanks and I enjoy reading all the posts and think its great how everyone helps out others with questions problems etc. I will do the same with my limited capabilties!!

cps
06-18-2009, 06:42 PM
Hi wstan01, i could be wrong but i think if you look around the bottom of the hoist rams or on the bottom side of the cab in the same area it should be stamped around that area! I think!!!

Hope this helps!

finaldrive
06-21-2009, 05:01 PM
Hello guys-- Newbie to the forum!!! can anyone tell me if the serial #s are stamped into the frame on a grey market machine? I am parting one out and some genious removed the data tag. It is a Hitachi 120 Thanks and I enjoy reading all the posts and think its great how everyone helps out others with questions problems etc. I will do the same with my limited capabilties!!

Email me a photo of the machine, I'm sure I can ID it for you from that.
Engine should be an Isuzu 4BD1T, check the valve cover for the arrangement number, that would help to.

482budget
06-23-2009, 11:10 PM
Wstan01
I can tell you that a Ex120-3 has a single stage pump HPV 091 ES. But I can't tell you about the later models 4 and 5.
If you have a -3 I am looking for electronic parts for mine machine (not sure what yet). It is in getting checked out right now.
It is getting slow and stupid for some reason on the track drives and stick cylinder. Pump and pilot pump are doing what they suposed todo ( flow and pressure).

danc
06-24-2009, 09:35 PM
fast motor repairs:

jetta125 as you say the gearbox cover was repaired before, the outer welded plate can be seen on previous posts, thankfully a little leak sprung out through a weak spot where it was welded, and I caught the track motor seal failure fairly quick.


I have it all together with a new spud welded in place to control thrust, and stop the input gears trying to ride out though the cover.

When I stripped it down I found the input shaft gear had white writing 'ex120 21 teeth', so this had been replaced before, this got my thinking/hoping someone had fitted the wrong ratio shaft , some guy stuck for a part, used what was available etc.... but on pulling the cover from the slow side, it too has 21 teeth, so much for wrong gear ratio theory, :rolleyes:



The old spud was was well worn down, and a full circle, so this time I have cut a few slots to aid oil flow around this area.
BSP pipe fitting bungs are cheap, I got a few of these and have drilled/pressed in a magnet. I will running with one of these bungs instead of the original filler bungs,for a while to catch any metal flying around inside. Iím surprised the original bungs are not magnetic

Iím checking clearances to the spud with some sealant, (some cling film to control the mess) Take it off next day, measure the thickness.

The teeth marks on the cover show how the gears try and head outward, when the spud wears down.

danc
06-24-2009, 09:44 PM
Slow motor repairs:

When I pulled the gearbox cover off this side to count the teeth, I pulled most of the gears out, to find them all turning freely, all looks good.
Iím going to get a pipe made to enable swapping over the pumps outlets to the valve block next so I can continue investigating why the other motor is slow.
If the pumps are giving different flow rates, can they be balanced?

jetta125
06-26-2009, 10:30 PM
Hi D,looks like your final drive has a lot of work done,if some one replaced the centre shaft theres 2 reasons,she chewed the inner splines or the outer gear which is most likely, u need to pull out the outer and inner planetery gears and check all 3 bearings on each, if it ran on bad oil these are first to go, u could swap all the gearbox parts from 1 track to the other to see if that moves your problem, hav you checked final drive main bearing ? ,also you can tweek the pump flow 2 adjusters on bottom of pump head, these are very sensitive..

Aardvark
06-27-2009, 03:15 AM
Whats the go with the pump adjustment Jetta ?
Does that adjust the swashplate does it mate ?

jetta125
06-27-2009, 10:18 PM
ya adjusting these increase the pump flow, but u want to check your main pressure release valves first,connect pressure guage to hydraulic pump, 8mm allen key? stop 1 track and guage should read 300 bar, if not you need to remove ,these are found under the front of your chest valve ,very difficult to remove,32mm or 36mm spanner(a short one),with 17mm or 19mm long lock nut dropping down,take down complete valve, mark r measure position of adjuster,long nut is just a cap,clean complete unit.You,ll need a pressure guage to re-set these,1 pressure valve for each side of pump, with guage on 1 side of pump, stop the relivant track an u should get 300 bar on guage if lower adjust release valve with short flat screwdriver,these are sensitive,,
IF thats all OK ,you need to trace the pipefrom your bad track to the pump,lift this track and adjust the relavant valve on pump outwards(i think),very small movements, this will increase flow ,and should speed up your track,without a flow meter you,ll need to play with these to get speeds right..
BUT you must keep in mind that one side of your pump could be a little weak???

danc
06-29-2009, 04:23 AM
I got everything back together yesterday.

I got a pipe made and swapped the pump pipes .

Both motors behaving the same, so the pumps seem to be matched.

I put the pipes back as they were.



Jetta125, most of the work done so far is on the fast finaldrive. I ran it for around 15mins since re-sealing, and all seems good, no leaks, nice and smooth. :)


The slow one:


Prior to this I had pulled the cover off the slow finaldrive.

I removed the 2 sets of planetarys, all 3 gears on each turning smooth.

I havenít yet checked the main final drive bearing,

Things ruled out so far:

Pumps, both are giving similar flow, the pipe swapover showed similar speeds in each finaldrive.
Gear ratio, both are the same ( 21teeth on input shaft)
Swivel joint, resealed this.

Iím doing a idler seal change on this side next, so when the track is off I can pull the input shaft out of the box, and see how smooth the drive turns manually.
If this turns up good, motor case drain check, pull apart the motor,
The hardest part of pulling the motor is getting the pipes off !, rest is easy

jetta125
07-02-2009, 07:16 PM
Well ,did u get those pipes off ? how did the rest go ??

d47u
07-03-2009, 06:14 PM
hi , i have a similar problem on my older UH081 with one track motor that will rotate the traks when lifted off the ground and the other that is lazy but works.
we did the seals in the center joint , all new and ok , then then the center distributor on the faulty motor ,found missing broken orings (we recovered these from the filter in the tank) fitted new orings , still no change cheecked oil pressure was well within spec , looking like we will have to pull down the actual piston motor and do all those seals in both motors to reslove our issue , sorry to be so negitive i could also do with some advise on the UH07-5 drive motor even a page from a manual would help
i think like yours problem ,at least the tracks can rotate with no load so i feel the oil is by passing in the motors them selfs , we checked all the soliniond valves they all worked good as well
have not yet gone any deeper
all the best john

wstan01
07-04-2009, 10:24 AM
Wstan01
I can tell you that a Ex120-3 has a single stage pump HPV 091 ES. But I can't tell you about the later models 4 and 5.
If you have a -3 I am looking for electronic parts for mine machine (not sure what yet). It is in getting checked out right now.
It is getting slow and stupid for some reason on the track drives and stick cylinder. Pump and pilot pump are doing what they suposed todo ( flow and pressure).

Thanks to all that replied with help I did find s/n stamped inbetween boom lift cyl frame at base of boom on frame, I did have a 4BD1T Isuzu and not sure yet on pump, again thanks to all for your help. s/ n 12n 30463

d47u
07-06-2009, 03:39 AM
hi guys can i ask a quick question it the track motor in the uh07-081 a similar style to the one in the photos? as the problem i have with mine seems similar
cheers

danc
07-06-2009, 03:47 AM
Didnít get back to this yet with all the other stuff Iím doing with the house.

After stripping the good motor while I had it off, from what I can see there are no seals that will cause the motor to have excessive internal leakage.
It will be down to either wear between the surfaces of the pistons, block or top plate..

The only rubber seals within the unit are the brake seals, and o-rings for mating surfaces when the back cover is pulled off.
Unless the brake mechanism can go bad, and fail to fully release when the pressure is applied.

Iíll report my findings when I get it pulled off and stripped down :)

danc
07-10-2009, 03:57 AM
Still havenít got around to removing the slow track motor yet, but others are having track motor issues, so I have some pics from when I replaced the output seal on the good side, they may help someoneÖÖÖ


The motor is held on with the two bolts marked in green...

The 4 hex bolts marked in red hold the back cover on.

I didn't have a puller suitable so I removed only two of the hex bolts diagonally, and fitted longer bolts , to pull the motor away from the planetary box...
there is an o-ring seal beween the two, revealed when they separate.

danc
07-10-2009, 04:06 AM
Some oil will spill out of the planetary box if not drained from the other side.
When the motor comes away, Iíd stuff some rags into the box to keep the crap out.

Take the motor to a cleaner place, then remove remaining 2 hex bolts, and pull off back cover.

When pulling off cover watch the top plate doesnít fall to the ground.

Note the thin metal rod insert through the centre shaft to keep the block steady. Only really need this for alignment when rebuilding

danc
07-10-2009, 04:19 AM
Lift away the metal disc to one side ( red)

2 more o-ring revealed at this point ( green)

danc
07-10-2009, 04:24 AM
Look down the centre shaft of the block, a small circlip holds in place, remove from itís groove, and slide it up.

The block will then slide off the pistons.

Some rags around the sides, to stop metal to metal contact help protect the pistons when they tip over

danc
07-10-2009, 04:26 AM
Rags removed for pics

danc
07-10-2009, 04:30 AM
Remove lower circlip

danc
07-10-2009, 04:37 AM
Take care not to loose the ball thatís sits at the bottom of the centre shaft.

danc
07-10-2009, 04:39 AM
When the centre shaft is out, all pistons can be taken out .

I was looking for cracks/damage below these, but all was good.

Beyond this point there are discs and brake seals, no pics, but Iíll get them the next time.

To further strip the unit and change the brake seals, the shaft can be knocked out with a light drift from the other side ( where the output seal is)

danc
07-10-2009, 04:45 AM
When rebuilding I found that the metal rod shown earlier helps a lot as a guide.

Another thing I did was remove the other 2 small hex bungs for a tie wire to hold the top plate in place

cps
07-10-2009, 08:23 AM
Your getting real good at this dan!
Think i'l send you any motors i have in the future:drinkup

danc
07-10-2009, 10:05 AM
Hey cps sure thing :D

Iím hoping to tackle the slow motor when I get a break from working at the house, so gotta do it all again, will be easy next time. As I said getting the big pipe nuts off, is the hardest bit. 5í levers and lotsa shouting.:bash

Another thing I did was do a rough gauge on bore clearances.
I knew this was a fast smooth motor, it was stripped for a seal failure, no performance issues.

I took each piston with the block removed onto the bench. I coated each piston with a film of hyd oil. Then 1 at a time I let them slide into their bores. On all pistons none dropped through quickly. They slid down the bore nice and slowly under their own weight. Good enough clearances for me.

This for me is my benchmark for the others side when I strip it down, unless there is something more obvious, top plate ..etcÖ ( or the fault is elsewhere)

BTW there are guys out there that have done lots of these Iím sure, so feel free to comment/ suggest other methods

This motor is back on the machine, and going great

AtlasRob
07-10-2009, 06:32 PM
This motor is back on the machine, and going great

VERY impressed :notworthy

That is a lot of very useful information for anybody thinking about entering a track motor.

Me ! I think I'll pass, thanks :D

willie59
07-10-2009, 09:07 PM
I agree Rob, danc layed out a nice procedure, and the pics are excellent! :notworthy

danc,
are you saying your having difficulty getting the fitting nuts loose? The trick I have done tons of times to great satisfation is a hammer, and AtlasRob will vouch for me on this one :). Take a good size ball peen hammer and give one of the flats on the side of the nut several good smacks, hitting dead square on the flat. And if you can smack a second flat next to it is even better. After this, you should be able to remove fitting nuts with ease. ;)

krich
07-12-2009, 02:19 AM
Danc
Good job, but just some things to remember when stripping motors and pumps, as you have done always mark position of pistons in there bores, normally the critical things to look for are unusual scratch marks particually on the presure plate to barrel mating surface, if you can feel it with your finger nail then it will leak pressure, also base of the piston on the ball, also look down the center of the piston and you will see a small drilling, this should be clear.
The most inportant advice I can give you is keep it clean, dont force it particually when you reassemble it and remount the motor head back on the travel motor housing, it should evenly close together and the last 3 or 4mm should be under some pressure as you are compressing the barrel spring, dont forget the small oring as this operates the brake.
Also most importantly make sure you bleed the air out of the motor when you start it up normally do this can be done by jacking the machine up, engine on low idle and rotating the track slowly in both directions for a couple of rotations, two things kill hydraulic system, no oil and air.
Good luck.

Mopar Todd
02-05-2011, 02:20 AM
Good info guys . . . way to help the man out. I have a couple ideas as well.

* Have the lines been traced all the way from the valve stack to the slow motor? If the steel lines in forward or reverse have been smashed, the flow from the pump will be impeded which will slow the motor. If there are any sections of hose they would be suspect as well. I've seen hose liners fail even when the hose looks fine from the outside. The liner can wad up inside and restrict flow. If there are any bent tube fittings look to see that they have not been pulled on and bent further. ( A bent tube 90 should not be bent 120 degrees and flattened out)

* Remember, since the case drains are tee'd together the internal seals of each motor feel the same pressure as case flow exceeds diameter of case drain line. Pressurized oil finds the path of least resistance. If the slow motor has a healthier shaft seal than the fast motor, the fast motor shaft seal will fail first, even if the slow motor is the one with large case flow.

* Heat is a clear indicator of excessive motor or pump clearances. If the bucket is placed against a VERY stationary object and the machine is tracked forward, the case drain line on a bad pump or motor won't take long to heat up. I've seen bad pumps and motors turn blue paint brown from the amount of heat produced.

* Also, port reliefs at the valve bank could be allowing pump flow back to tank on one side.

Hope this helps, Todd :beerchug

ditchdiggerjcf
02-05-2011, 11:46 AM
If swivel joint is bad, the machine will not travel worth a damn.

danc
02-18-2011, 06:53 PM
Hello back after a long break, Iíve been doing very little travel with the machine since

but I thought Iíd post the root cause of the track motor seal failure on my fast motor.
( I never got round to stripping the slow motor.. itís moving upward on my to-do list before summer!! )


The track motor output seal failure was due to a blockage in the case drain, in the upper section of the swivel joint.
After resealing the swivel joint, during refitting, all ports were stuffed with rags..
Fearing the crap from the upper body would enter the ports, when pushing it through the large rubber grommet on the frame.

Main ports point upward, case drain to the side. The short fitting to the case drain port must be removed,or it will tear on grommet, itís a tight fit.
So a rag was stuffed flush into the portÖ.
Usual story got called away in the middle of fitting the swivewljoint, :rolleyes:back 2 hours later, removed all rags, fitted fittings, and pipesÖforgot there was a rag stuffed in the case drain portÖ:Banghead

mexlee
12-28-2011, 09:33 PM
Dear danc,
I had hitachi ex120-1 and got the same problem like yours.the other side track move faster than the other.before that both track wont even want to move an inch,so i ask mechanic to fix it.they install a new vavle plate ,rotor ( cylinder block ) and piston assy. After the new part was installed, there was still the problem. However, after the mechanic did some adjusting to the main pump, both of the track move with same speed. Hope this help :-) .

mexlee
12-28-2011, 10:39 PM
86798

Dear all,
Recently i just bought a second hand hitachi ex120-1 with tons of things to be done to be perfect running machine, the 1st owner used this machine for 16 years and lots of things has been modified, lots of wiring were missing. The tortoise/rabbit buttons were unplug, no lights, no diesel fuel gauge meter to look onto, all of those sensor and the electric wiring were gone. But still the machine run ok for now. Im planning to connect all those sensor and do a new wiring, for your information im a newbie in excavator world with zero knowlege without any manual book to seek help LOL, i just had a basic knowledge with cars so i think this will help me a bit. As u see the picture with rounded green marking,im wondering is it a sensor or what? Where is it to connected to? Mine still attach but without the wiring someone cut it. Im stuck in this and my brain blowed off LOL, can someone help me with this? Any advice?. Oh by the way can i install intercooler for my ex120-1? I want to install it but need some advice before doing it..

chuck42
07-18-2012, 03:45 PM
Hello everyone, i have a Hitachi EX200LC that is having the same problem of one track being slower than the other> for about 1 hour the machine works fantastic however when she is running at temp is when it will start to get really bad, by the end of the day it will almost not move, all i have done so far was inspect fluid levels and for visual leaks... not sure if this matters at all but when i pulled the plugs to check the fluid level i noticed the slow side had a considerable amount of pressure build up compared to the other, not sure if that helps!!

fiathitachi130
09-23-2012, 07:49 AM
new to all this. have a fh 130-1 and looks very similar. did you find out what the solenoid controls? On mine there are three solenoids, two of them control the engine idol.The third one is piped to the bottom of the main hyd pump. Machine seems to work fine, but always wondered if this was to give more hyd pressure or more track power or something like that?