hi. our hitachi is again fooling with us. works fine, but the bucket cylinder got very slow just in a snap. it takes about two minutes to get it move from side to side. owner said that he think maybe the digging boom got slower before. bucket moves little faster if i do an other movement at the same time. i think it is somewhere in pilot hydraulic system, or in main valve bank is the bucket valve sticking. any advices where could i start?
Hi there, not fimular with the Hitachi system, but that problem on a Cat would be in the resolver system. Not much help I guess.
Hi! Im not really sure what is resolver system?
You check the cylinder for internal leakage? ie piston seals.
doesnt feel like internal leakage. it really takes for two minutes to go from side to side, but there still is power even its REALLY slow. and it gets little faster when i do some some function to the top and leave the lever at full movement. and, the epc box shows me red lights blinking. so there is some electric pain.
It's part of the pilot system. I honestly don't even know if you have the same kinda set up. One simple thing you can do to narrow the problem down would be to swad the bucket pilot lines with the boom pilot lines. You would have to do this at the joystick or under the cab at the pilot manifold, and NOT at the control valve as the boom will be 2 pump flow and the bucket 1 pump. If the problem moves over to the boom, then I would pull the pilot control valve ( joystick ) out and strip it down. If the problem stays with the bucket cylinder then pull the bucket spool out of the control valve. They may seem like a lot of work, but it's nice to know that when you pull a part off you are working at the right thing.
I have also seen the bucket anti cav valve cause the same problem but the easiest thing to do is switch the pilot lines with another function and see what happens, as long as the bucket feels strong then there is a really good chance the seals are ok. Does the machine mistrack?
What or where is the anti cav valve? I think when i pull the lever to move the bucket, i think it tries to fight back little the joystick i mean. And the pvc:s confuses me with the red lights flashing. Ive got a feeling about the buckets spool valve at the control valve, because any other movement taken to the top strenghtens the bucket move. But the red lights, as i remdmber correct, shows an electric problem. Or could a not-moving spoolvalve fool the sensors? Tracks work normaly, as everything else.
You don`t need to swap anything. The manual already will tell you what pilot pressure is, make an inline running tee fitting on either top or bottom pilot line so you can see pilot pressure right at the spool cap. your pressure is either at spec or it isn`t. The spool either moves or it is stuck and not going full stroke. The reason asking if it mistracks is one pump runs left track and one runs right. If it mis tracks as soon as you begin travel, one pump is not going to full stroke. Always remember, speed is flow, power is pressure.
I know i should next measure the pilot pressure, it woult tell a lot. I just got home and i got distance to the machine 75 kilometers, and i dont have t-part and pressure gauge to check it. Does someone remember what size should it be? Flow is speed, pressure is power, good thing to remember. I did not think this when i started this thread. This is why i thinked from the start that the problem is that the spool does not open full, just a little. The electrics still are hounting on my mind.
There is probably nothing wrong with the electronics. The lights on those computers are supposed to blink about once every second, this shows that they are working. Like the others say I think it's a problem with your hydraulic system.
yes, i think so too that the problem is in the hydraulics. but as i remember, light are suppose to blink green when everything is ok. but ill get back to that if cant find nothing wrong from hydraulics. but as i understand, there is no any electric component what could cause problems like this. just some components using the autoidle and other functions. could the tee fitting be just 1/2"?
If I remember I think it is #4 JIC on the hose to spool cap. Yes the control boxes are supposed to flash a steady 1 second or so red flash. If you move the joystick and the pilot pressure is correct and the spool is free to move, the pump is at stroke and your cylinder isn`t leaking internally, something has to move. And no you won`t be able to feel like the cylinder is leaking internally, it needs to be tested for a leak.
im pretty sure ihere can not be an internal leakage in cylinder, because when i move the bucket cylinder, it does not load the engine, but when it gets to the top it loads the engine like any other movement taken to the top. and it gives me the feeling about the spool valve, i know one way or other its not opening correct. but i think anything can be possible with these things machines owner takes my speaches really sceptic about the hydraulic problem, he just says its the box or its the pressure switch or some else electric part. but im 95% sure when i get there with pressure meter, we find out whats the problem.
i tried to change the pipings from the fc valve, so the pilot pressure came from turn to bucket cylinder, still not moving. i could not measure the pilot pressure because i still dont have the parts to engage the meter, but i think that in the fc valve cant be such a problem that blocks this hard the oil flow. but there is some thing that makes me confused. its this when i try to turn the bucket, it moves so slow it can just be seen. but when i pull out the digging boom, and keep the lever at full move, and then turn the bucket it moves much faster. not as fast as normally, but not much slower. i tried to knock the relief valve (as i think it is relief valve) and friend was moving the bucket. he said that always when i knocked it it moved faster, but i m not sure about that.
so i took the spool valves out, found a little metal piece from one. now we noticed that also the upperstructure turn is sticking often, so next im going to take out the fc valve and see is there more metal in, because the both, turn and bucket operating pilot pressure hoses are going through the same valve. the turning is quite funny, it does not turn, but loads the engine, but when i touch some other function it wakes up. maybe it will work some day.
found nothing. now i really need to get the pressure gauge engaged. i started to think maybe theres some pain inside the control valve, im pretty sure those metal pieces came from it. sounds expensive.
what could be the possible places that could cause this problem? im pretty sure theres no enough pilot pressure going to the spool valve.havent got my meter engaging parts yet. whats the function of that solenoid valvebank? this really makes me crazy. other functions works well. only turn and bucket cylinder are not working. turn locks up and does not open before i touch some other function and it wakes up. only place thats connecting these two functions is the fc valve, and theres nothing in it, just tree metal balls. i ripped it off and cleaned it but nothing changes. the pressure goes to the levers from lock valve, but if there is something in lock valve it should effect to other functions too. i changed the pipings from the lever, so the lever should be ok too. between the lever and spool valve there is just the fc valve, where is just a straight hole in it. even if the pump would be lazy, it should too effect other functions. help?
Maybe you should do speed test on all functions because flow combiner will compensate for a bad pump making it seem that other functions are better than they really are. Does this machine track strait?
The flow combiner valve is meant to supply one pump flow to both tracks when a front function is used while traveling. So if it continues to travel straight but slower when you use any other circuit, it is doing it`s job.
yes, it is tracking straight, as ive been driving it. pilot system has it own pump, and im pretty sure it is somewhere in pilot system, because bucket does have its power left, its just slow. so the spool valve is not opening for some reason. what is funny it is like ten times faster when i pull the digging boom or some other to full movement and keep the lever pulled. i just dont get it how can that make difference. tomorrow ill go to hydraulics shop to get some parts and ill take now the parts to get the pressure meter engaged. the pilot pressure should be near 50bar, am i right?
I'm not familiar with this machine, but most machines have some way of upstroking or destroking the pumps depending on the demand. This is sometimes done through a load sensing function. Someone earlier mention a possible issue with the "resolver" network, thats how caterpillar does it in some of its machines. Its just a series of shuttle valves that lets the highest pressure through. A red flag to an issue with the resolver network is when one function is very slow, but speeds up when another function is used at the same time. Might be your issue
It`s been a few years since I`ve been into one, but whatever a "resolver" is, there isn`t one on a Hitachi.
Sorry what I meant to ask is was is one track slower than the other, lift tracks one at a time and count seconds to do 3 revs then do the other side and compare if one is slower than I think pump or regulator, if this is the case the put gauge on main pressure port of pumps if it makes relief pressure than its good and your maybe looking at regulator problem. Or possibly O-rings on control spools shot on pressure getting by and not stroking spool or some junk physically stopping spool movement. If it is the spool getting hung up than your flow sense will be low and will stroke the pump.I chased a similar problem around a 300-3 and it ended up being a regulator problem.
today got the t fittings to measure some pressures. then ill tell you do i have enough pilot pressure. it is just like the spool valve is not opening. it does not load the engine until the movement reaches a top, then it strokes the engine as normal. really weird, but now ill get some facts with the gauge. i will do the track test when i get there. i just dont believe its the pump because it started in a snap.
The pilotpressure is fine. Also the cylinders gaskets seems fine, bucket stands in place even if i pull the excavator with it. I changed the shuttle valves between an other function, still quiet. Next ill do the tracking test. Where is this regulator, and what is its real full name? Could search for some info. Could it be fixed, or replaced only. How much work it causes? Thanks really much this far, yours help is worth of gold to me. Johnnyboy, tell me about your 300.3 case?
If your finding metal parts in the control valve than maybe you should have a look in filter too. How do all other functions work? one weak track?
Did not yet test the tracks with second counter, just drove it a bit and it feels like its going straight. Also tried some boom functions when tracking, didnt notice any mistracking, only slows down when boom is moved. How did johnnyboy your hitachi story go? I really do not know where to look to solve this problem. Spool valve moves freely when its taken off, it has got pilot pressure, shuttle valves have been changed.
Our problem initially was a bad pump, then reman pump we got had regulator problem so it was hard to diagnose. Machine will still track strait with one weak pump because it has flow combiner in control valve- this is why you need to test track circuits seperatly. One pump for each track. I have never worked on a ex100 either so I'm not familiar with this machine. With dual pumps there is a one pump, two pump stroke -meaning bucket out=one pump and bucket in=two pumps. If your tracks are equally powerful when used individually than both pumps are probably good. Try switching pilot lines at control valve from arm to bucket you will have to swap all four lines and see if that makes bucket work as it should. HeavyEquipmentForums here is link
With pilot lines do you mean pipings going from valve block to cylinders? I suppose thats next thing o should do. If the bucket works normally with other functions pipings, the problem is in valve block somewhere. Just cant reaconize where. Well, theres like three weeks when we should have allmost ten kilometers
With pilot lines do you mean pipings going from valve block to cylinders? I suppose thats next thing o should do. If the bucket works normally with other functions pipings, the problem is in valve block somewhere. Just cant reaconize where. Well, theres like three weeks when we should have allmost ten kilometers ditch digged and havent even started yet.
No not pipings but the pilot lines that control spool movement, there should be one on top and one on bottom that push spool back and forth, and remember that I'm just assuming your machine is similar to the 300. Any chance you could take a pic of pumps and regulator lines on top?
Have tried it, and also measured pilot pressures from spool cap. Pressures were normal, and bucket did not move with another pilot line. I think problem is in main valve bank, but have no idea where in it. I changed shuttlevalves which are situated close the pipe outlets, one for each pipe. Took them from the next spool and changed them between. Nothing happened. Cant understand. I scare that there is some broken line inside the valvebank because of the little metal pieces at one spool valve, but dont know how it could be tested. But feels strange still because there is still power in bucket just only not flow. Like a broken shuttle valve.
just to clarify how are all other functions? Also you only have one variable pump- is this correct?
Correct, all other functions are fine, just the upperstructure turn has some issues. Im really not sure about the pump, but as i know there is one variable pump.
Don't know about the ex 100 but on 120 to 220 ther are proportional valves on some spools. Thier function is to restrict the flow on one circuit so that other functions will work. If one was closed it would only allow a small amount of oil through. From memory they are either in front or behind the bucket spool. Have another look at your shuttle valves and not just the one next to the bucket spool. On a the bigger models there are also solenoid valves that overide the proportional valve,these can be identified by looking fo tubeing that goes from a solenoid bank tothese proportional valves. If your machine has a steel tube going into the area next to the bucket spool disconnect it , plug the tube end and give it a try You have metal in hyd system so you need to find where it came from. Excavators a notorious for the slew motor finding contamination because the anti cav line suck unfiltered oil into the motor when decellerating from slew. Regards Mike
There is this solenoid valve bank or something next to the main valve bank. http://m.ebay.com/itm?itemId=251384254252 theres solenoids like this six or eight peaces. Their name is proportional something. I just dont know this solenoid valve banks function how does it work and where it effects. Could the problem be in these solenoids? Im writing with my phone, i have the pictures and partlists at home in my laptop so i cant now show you what i mean. Ive heard that the hydraulics are same in ex100 and ex120. And some of the terms i use might be wrong, pictures would help a lot in this thread so i could be sure we are talking about the same things.
I went and took a look at the valves and thinked your words, there is going little steel pipe from each spool to this solenoid valve bank where is six solenoids or proportional valves. I swear the problem is in there. Im sure. So if i unplug the pipe and plug it, it should make a difference? Im not sure do i have parts to plug it so i open few valves and look inside. There should find a little spool valves inside. Thank you mike, ive been thinking a long time this solenoid valves function.
Be very careful with these valves. The solenoid does not do anything under single operation of a function. Not sure the exact sequence but it is something like when you move two spools the lower pressure one will close off a bit and also when you change dig functions it sends a different pressure to these. I would look at the section where they screw into the main control valve first. Maybe swap a couple around or unplug the wires. regards Mike.
Thanks mike. Took off the spools that the solenoid valve operates at main valve, nothing unusual. Took off two solenoids from the solenoid valve bank, took a look at them, everything seemed fine. Had no multimeter by my hands so i swapped the solenoids places, no cure. Then i unplugged the wires from the solenoid that works for the bucket spool, and it woke up! Theres some problem with the wirings maybe, next time ill take my multimeter with me so i can do some research, but i just left the wires unplugged so far, seems that it does not make any harm if unplugged. Thank you very much guys, your advices helps me step by step closer to learn this machines parts and functions and how one effects the other. Thumbs up for these forums and helpful people. Someone like me can learn a lot from here and save thousands and thousands of euros.