Hi guys im back again after a long season working in a quarry, I have a problem with hyd in a 988B, first i explain what i did to that machine, the equipment was stoped for more than 1 year, many missed parts, (brake acumulator, 2 hyd pumps, tranny pump, oil cooler and many small things) I install all the missed parts new and used but I took them from a machine that just broke engine, now the problem is this. today when i come back from quarry, they called me and told me that boom and bucket stop working after 1 hour of work, i just told them was tha hyd oil cooler that is in radiator, but im still thinking what else can be the problem. any suggestions? Thanks in advance Lou
Check the pilot system first. Later Bob
Where are located Bob? Sorry I misspelled last part of my last post I told them wash the oil cooler located next to radiator
Lets see if this comes through clear enough to read:
Some basic information on how the system is designed to give you a starting point. Copied from SIS: The hydraulic system has two gear-type pumps. One is a double-section pump and the other is a single-section pump. The large capacity of the oil from the single-section pump is for the lift and tilt cylinders and for other hydraulic implement attachments. The large section of the two-section pump is for the steering system. The small section of the pump is for the pilot oil system for the implements and for the hydraulic brakes on the wheels. Assuming this is how your loaders is configured. A quick check would be to see if you had working brakes, parking brake releases and wheel brakes apply. This would tell you that the pump that supplies the oil pressure for the pilot control system was still working. Some more from SIS: An accumulator charging valve divides the flow of oil, from the pump, for the brakes and for the implement pilot oil system. There is a filter for the pilot system oil from the accumulator charging valve. A pressure relief valve in the flow of oil from the accumulator charging valve keeps the pressure of the oil in the pilot system at approximately 325 psi (2250 kPa). The flow of oil from the accumulator charging valve that is not needed for the operation of the pilot control valve goes through the relief valve and through the oil cooler before the oil goes into the tank. An oil cooler bypass valve opens when the pressure of the oil through the cooler gets too high. High pressure of the oil through the cooler is caused by cold oil. Oil passages in the cooler that are not clean is another cause for high oil pressure. The complete Serial Number might help to get more information. 50WXXXXX?
Ken thanks in advance, tomorrow i move to quarry so i let you know guys what happened, the only thing here is everything work, only boom and bucket not
should i take the 2 acumulators i have and change them?
Sounds more like to me you lost the implement pump? If the accumulators were shot you might see some issues but I doubt you would lose any function completely.
The problem here is pumps are almost new only 20 hours work in other machine that blow up engine, and after maybe 30 minutes rest machine after problem start work again fine until warm up again
Never assume anything, but yeah, still more likely to be the pilot system as Bob/Ont says. According to the information kshansen provided if your steering and brakes work the two section pump is pumping oil from both sections, and the pilot oil comes from the brake section. The things to check in the pilot system are the charging valve which divides the flow, *FILTER* and relief valve. Have you inspected and/or changed the pilot filter? If you can read the page kshansen posted out of the service manual, it tells you where to connect a pressure gauge. Run it until it stops working and see if you haven't lost most or all of your pilot pressure.
Pilot filter? I'm still trying figure where is pilot system lol
From memory I'll give it a bit of a try! Standing behind cab looking toward rear of machine there are two doors. Open both and there should be two identical cartridge type filters near the center. One of them is the transmission oil filter, I believe a hose from the trans filter goes to a pump on the converter just above the drive shaft from the converter to the range transmission. The other canister filter would be for the pilot control system. I believe a hose from that filter goes right to the relief valve where you check pilot pressure, mounted on the right frame of the machine. If you are standing behind the cab you will be standing on two doors in the floor, if you open them on the right side near the top are two identical filters / strainers. They have a hex plug in the top and six bolts in the cover. I'll try to attach a picture from the parts book of them. I would remove the covers and check the strainers in both these. One of these is for the steering system and I believe the other is the hydraulic system and is in the lines leading to the pilot and accumulator charging valve. As lantraxco suggests when things stop working check to see if the pilot pressure drops way down. I'm also there is a breather on the top of hydraulic tank might be a good idea to check to see this is clean and not causing a problem. Also in the top of hydraulic tank there the two hydraulic filters, checking and replacing them would not be a bad idea. If many things have been opened and replaced on this machine hard to say what may have gotten in to some place to cause a problem.
Do I read this right? The boom and bucket stopped working after one hour working fine, then after sitting for 30 minutes cooling down started working again? Interesting! Not sure what this means but I still would start by checking filters and pilot pressure. And just for the fun check clamps on all the suction lines to the pumps.
Guys I'm desperate now
Today I checked all filters and replace them, check pressure from pilot was OK, but even like that I replaced, change accumulator, check front valves (the ones under bucket), found small valve broke replaved , the big one under that replaced and keep doing same ****, it works 1 hour sometimes more some less stop work boom I let machine running for 5 to 10 mins in low rpm and start work again for 20 mins and keep doing that all day please helppppppppppppppppppppp
Ken if you mean the 2 small filters behind cab in floor I already checked, if you tell filters inside tank I don't, also many air go out from tank when I stop machine (not normal amount) I changed the cap for another old style, also I didn't saw the breather, by the way I told you guys what I did today in previous page, so you have better idea
Sounds like it's sucking air someplace, don't know if that's related to your problem.
Hyd are overheating. Check the brake charging valve is cutting in and out correctly. If it doesn't cut out the oil flow will go over relief and heat up. Later Bob
Well Bob it brakes all the time even when boom stop working
Two things. When it stops working do you still have good pilot pressure? Kind of a shot in the dark but have you looked at the main pressure regulator valve? It is mounted one the large valve assembly above the front axle. I have circled it in the picture below. Here's the cross section view:
Yuupp I checked that one and replaced all the inside BTW valvle number 5 was broke I replaced, and pilot pressure still ok
Also I'm thinking today change valve 22
If the charge valve is jammed the brake section oil will always go to the brakes and run over relief, not to the steering with a free return to tank when not turning. This could cause heat build up. Later Bob
Do you have image how charge valvle looks?
The brake accumulator charging valve is #72 (inside the red circle) in the illustration below. It's mounted on the brake control valve.
I was wondering. If the accumulator charge valve was contributing to this problem would not the pilot pressure drop off when the problem with the lift and tilt present itself? If the fittings were available out of curiosity I would like to tee a test port into the port on the end of the cover on the control valve that the pilot valve puts pressure to to raise the bucket or tilts the bucket. My thinking here is if I knew when the machine was in the failure mode I still had good pilot pressure being applied to the end of the lift spool I could eliminate a large amount of the system from my possible cause. One thing not mentioned is how this problem presents itself. Is it like one lift of the bucket it works fine and the very next second no attempt to move at all or is it something that comes on over a period of time? Not sure what exactly either would mean right off but I always like to have as much information as possible. I know from memory most of the 988B's we had came with Tyrone Gear Pumps, but did any S/N ranges use a Vickers Vane or an axial piston pump. The 988(A) 87A loaders at different times used each of these three pumps.
ok lets start serial number 50W346 (yes 346) second if brake acuumulator has a problem doing the work as bypass valve, should tha acumulator not stop all hyd system, i mean steering, brakes? i left machine in quarry i came to buy the filters inside tank, (and win some time) also I want all you know, why i replace everything you tell me, next to this machine there is an other 988b that blow engine, no torque converter, no hyd pumps, oil cooler and was working perfect before the engine problem( i saw it), so owner told me use all the parts i need for this one im fixing, so if i need change brake accumulator is more easy change it than fix it, Ken now i explain about the problem itself, when you start machine, works perfect everything (I mean PERFECT) after 1 or 1.5 hour later start the problem (it just froze equipment, no up down, if was on top when started stays there until they stop machine and low it fast ) , only boom and bucket, you have 2 options first stay in low rpm and wait 10 minutes for start work again , or stop machine maybe same amount of time and start work, (really this is driving me mad) today i check the breather was cloged i clean it and now dont spit air in filler cap when you open even warm, so guys any help is welcome also im happy see you again Nigel. by the way Bob and Nigel I aready change accumulator, for a working one also i have other if i need change it again
If you are telling us the lift arms wouldn't move, even lower when you have this problem the valve spool must be jamming up. Later Bob
Valve spoo, where is locatedl? And y,es are lift arm am bucket
The spool I am referring to is in the main control valve for the hydraulics. Be very careful, the lift arms and bucket must be supported when working on the valve or they could fall on someone and kill them. The valves are usually mounted with 3 bolts to prevent warping, check they are good. Then check out the valve for signs of spools sticking. Later Bob
You mean the valvles that are between lift arms? Like kenhansen post in previous page?
The valve spool would be on the main valve body that is mounted above the front axle. Wondering if one of these spools might be scored and when they warm up enough from working they get tight in the valve body. I believe it is possible to remove the spools with valve in machine. Only real problem is getting room to work safely as you probably need to support the bucket and boom to get access to the valve body. One way we have done it in the past is to put the bucket in the body of a large haul truck. The next problem might be getting the area around the valve body clean to avoid adding to the problem with dirt getting into critical places. Then relieve any pressure in hydraulic tank. Not sure how much oil will be lost when spools are removed. With the cover off the front of the machine you should see two housings about 2 inches across and about 3 inches long pointing forwards and they will have fittings with steel lines of about 1/2 inch diameter connected to them. If you disconnect the lines and remove the bolts holding the housings to the main valve body they should come off and inside are the centering springs for the spools. The spools should pull right out with the springs attached. The one on the left (as you are sitting int the operators seat) is the tilt. The one on the right is the lift spool.
so you mean this control valve?
Yes that's the one, the housings I was talking about are down near the bottom of the picture, numbers 6 and 7 are the elbows and the seals for the lines I mentioned. If you had a way to tee into these fittings and test for pressure while it was acting up it could point to where the problem is in the system. The small control valve in the cab the levers are connected to sends the pilot pressure down through the bunch of small hoses that connect to the back side of the bracket to the upper right of this picture. This pilot oil pressure then shoves the spools one way or the other to control the movement of the bucket and lift arms. If you do try removing the spools and have the boom raised even a little be very careful to have it supported well and all pressure released before moving the spools! Also spools are matched to their bores so I would do one at a time or mark them so they do not get mixed up. If you do find a problem with this valve at least you have the "Parts Machine" handy, good luck!
OK for me is going to be more easy take out valvles from the other machine, about rise bucket no problem I rest him over a cuadrat rock that weights 20 tons , my other cuestion is, in the other machine (the broke one) hose 34 is like in the picture, but in the one I'm fixing is direct connected to the intake of oil where a cover is, is that normal?
so if I understand correct the spools are located where yellow lines are (if like that no problem i change them) the other cuestion was, parts machine is like this hose number 34 but in machine im fixing is conected to green circle and where should be conected (blue circle) has a cover, also looks original because is not hose is a tube also just for be more relaxed im goinf to change valvle number 22,
Yes the spools are located inline with the yellow lines, as I said the spools are matched to the body of the valve so I don't think you can just swap them. Could get lucky but..... Did some looking on SIS and I see where that up until S/N 50W04173 the "U" shaped line was a steel tube and then went to the hose like in the pictures above. Not sure what is in that block/valve on the side. If I have time in the morning I'll try to look. Had to leave wife at the hospital tonight with kidney infection so will be busy the next day or so.
Thanks a lot ken and my best wishes and prays for your wife
Did some more looking about the green and blue circled connections and from here it looks like they changed where that "U" shaped line connects just because of the change from steel line to rubber hose. I can't see any other reason, does not appear to be anything inside that area on the different S/N ranges. Wife seems to be doing good, thanks!
Well I.m in quarry now I changed 1 spool valvle 22 and the body valvles in controls and did same, now I'm going to change the complete spools (with housing) and see what happens
Other thing operator tells me now is that if he work in hi rpm keep working but if he low the rpm start the failure even if he accelerate again machine
That sounds like it is a problem related to flow or pump loosing it's prime when oil is hot. Did you check the pilot pressure while this machine was in it's failure mode? What pressure are you getting? Are there any strange noises when running either before or after it goes into failure mode? What does the oil in the tank look like after running till the failure? Is it foaming up? I know years ago I had a 988(A)87A that lost all transmission function after I replaced a bad brake hose. What I found that time is the hose I had replaced had been rubbing on the suction pipe to the transmission pump. It had worn a small hole in the suction pipe and the new hose did not cover the hole. Removed the suction pipe and welded a patch over the hole and worked fine after that. How about as soon as it goes to failure mode you open the filler cap and see if there is pressure or suction in the tank. Then restart machine and see if that made a difference? Wish I could come up with better ideas but is difficult to do at such a distance. One more question. It's been a long time since I was running a 988B. If you were to start machine and while it is still working right raise the boom then shut down engine can you lower the boom with engine off? Then try the same thing when in failure mode. If it will lower with engine off when shut down before failure but not after failure I'm thinking that would eliminate the pump and it's piping from the cause. I know I ask lots of questions but trying to determine what does and what does not cause this problem.
When has failure you can low the bucket the only thing you can't do it smooth you need move control to the back position to realese some presure , no strange noises, I haven't check oil after failure and tomorrow I will be again in quarry. about noise yes i hear a strange noise when you stop engine after failure, in the intake tube from hyd pump you hear like a "glup" so what i did whas open the filter behind cab in floor, where the pressuure from pump goes, and what i saw is that hyd start go down very fast (i mean like returning to the pump) making glups all time and thet filter empty in cuestion of 5 min max time,
about pressure test, i just bought again yesterday my test kit, because i parked truck last thursday outside an store and left my kit in truck box, went to buy a beer, when i came back my test kit was stolen
Look inside the hyd tank for something floating around and intermittently blocking the suction line. Later Bob
Thanks Bob
That is a good possibility as I recall the machine was parked partially disassembled for about a year no telling what got inside things or even what the reason it was parked in the first place. From my experience everyone you ask will tell a different story. Could be someone shoved a plug or rag in some place to keep dirt out expecting to be back in a day or two to finish a job then never came back as customer ran short of cash. I'm hoping gladiatore is able to eventually find the problem as I'm sure he has been loosing sleep on this one.:drinkup
very true i dont sleep good for more than 1 week, and the works i depart 2am to quarry and when i arrive still at night so i need wait 30 mins so i can start have a bit of light for start work, is driving me crazy
now what i want do tomorrow is change all tubes and hoses from intake hyd to the pumps, check again pressures, and check tank, any other sugestions?
also im thinking check or replace the oilcooler bypass valve that is mounted in the back of chassis, because i touch when problem start the hoses and pumps and are hot (not like crazy but hot) and i checked the oil cooler hoses and was really cold, not even warm
Normal pressure pilot system 350psi when start failure 0 psi, after become cold again 346 psi
Well that is a start now just need to figure out where the pressure went. It at least means problem is most likely NOT in the main hyd. system, pump, tank and valves. Bob and Nige! You out there?
So what I need check now?
Have you had the pilot relief valve off and apart? That should be similar to the one for main pressure that is above the front axle. The pilot relief valve is where I believe you are checking the pilot pressure about the same height as the top of rear tire on right side of frame a bit ahead of the front axle if memory serves me right. If that is in good condition the next thing I might try would be the Accumulator charging valve. That is on the inside of left frame near the accumulator, Nige has it circled in red in message #25 The reason I might suspect that valve as the oil from the pump that works both the brake system and the pilot system (same small section of the two section pump for both) goes to that valve first then gets directed to the area that needs the oil. Thinking if the flow valve was hanging up or a passage was plugged it could starve the pilot system for oil. I'm going to attach a couple cut off SIS that show the charging valve and explains how it works.
Already separated pilot release valve and checked, good part I have 2 more accumulators
After change accumulator I tell you what happens
A bad accumulator will not give you zero pressure. It is possible if it has lost all charge that it may cause overheat in both the charge valve and the relief.
Charge valve? So what I need check? My brain is blocked
The accumulator charging valve in the two pictures above I posted today. The lower section of that valve is a flow control valve that controls the amount of oil going to the brake system and how much is sent over to the pilot system.
Finally it workssssssss
Thanks a lot guys I changed accumulator and the hose that goes to the double pump, give service to pilot system and change base from valves from controls because was broke, really thank you with all my heart
Yay!
Is this the base of the small valve up by the control levers? Might be interesting to take the accumulator apart to see if there is a real problem inside. They are very simple design. Just be sure to vent off all nitrogen pressure before starting! Four bolts take off head and then there is just a piston just like one out of one of the tilt cylinder inside only difference is no hole through it for a ram, seals just like a hydraulic cylinder. Glade to hear you have it working again:thumbsup:drinkup Now just waiting for the next phone call from someone with a problem, right?
There is a strap preventing two bolts from coming out until it's removed, it covers a hole that will let out any nitrogen if not drained. Later Bob
That's assuming the strap is still there! I have no problem dealing with the nitrogen systems myself having worked on the accumulators used in Cats since the 988 87A days and the 769A,B,C,D truck suspension cylinders among others. But at another plant in the company just this last year there was a mechanic doing some work on a front suspension cylinder on a 769 or 773 truck. He was reaching over the front tire and started to remove some bolts on the cover. Do not know if all the warning tags were still in place or if he had any idea of how this cylinders worked. Suffice it to say it was not a good outcome.
That strap I speak of has a seal and covers a hole through the cover of the accumulator, remove the strap and the nitrogen all bleeds out. If someone cut the ends off of it allowing access to the bolts people could die as a result. Later Bob
,now I start have other problem hyd oil is becoming hot but when I check tubes that goes to cooler are cold, so I'm going to check the lines.
Is there a thermostatic bypass valve somewhere in the system that sends hydraulic oil to the cooler only when it's hot..? I know on larger machines they have a habit of failing closed and causing overheating. The other possibility as Bob/Ont mentioned before is if the brake pump is not destroking correctly when the accumulators get up to pressure it will cause the oil to overheat.
Nigel do you know where is located that thermostatic bypass valvle?
There doesn't appear to be a thermostatic bypass valve on the 988B but there is a pressure-operated cooler relief valve right next to the cooler itself. It is designed to open and bypass the cooler if the pressure in the cooler lines is too high. If that valve is stuck open and the cooler is permamently bypassing then the hydraulic temperature would be too high.
Alrady changed and same
In that case my suspicion would be on the pump not destroking in response to the accumulator charge valve signal.
Nige that pump is a vane fixed displacement. the problem would be caused by the charge valve spool not directing the flow to the steering when the brake max pressure is reached. However I think cool lines where mentioned if so the oil isn't flowing to the cooler, check that valve again for correct assembly. Later Bob
Sorry, didn't check. I thought it was a variable displacement pump.
I already changed 3 acumulators
Accumulator only stores energy like a battery, keeps a reserve of braking oil under pressure. The valve that diverts the oil back and forth between the brake and steering circuits might cause trouble if it is stuck feeding the brakes and not going to the open center steering valve. But if the cooler lines are not as warm as the hyd tank then look for a obstruction in them. Feeling them is the best tool, just touch lightly and don't get burned. Later Bob
I think the B machines have gear pumps the 87A machines had vane pumps. Later Bob
h Also light from pilot system illuminates
Cooler hoses are cold hyd hot like crazy
Oil isn't going to the cooler for some reason .......... your challenge is to find out why. Maybe you have a blocked hose somewhere.
OK after you told me that I did some things, first check oil cooler was a bit clogged I put air to it, second changed the valve in chassis (next to cooler) next I drain all hydraulic oil from tank check all hoses and tubes ( all OK) after few time started do same (as bloody operator told me) I jump in machine and saw it works even in low rpm if you push an release clutch(left pedal) if you don't touch is impossible move lift and bucket, so I think is accumulator, I'm missing something?
Your neutralizer hose is hooked up wrong, maybe a lot more things. Later Bob
Which is neutralizer hose?
Look at the valves on the plate on the frame side behind the cab. Have someone step on the brake pedals rh then lh and watch the brake valve will move both times but the neutralizer will only move with the lh pedal. Look for a hose or tube from it to the trans. That puts the trans out of gear for loading the bucket. Will it put the trans out of gear? The rh can stall the torque the lh will not. Verify this first. Later Bob
I already checked all hoses and even change neutralizer this is almost in top of accumulator also I changed all Hosea and same trouble
ok let me show what i have been changed and checked so far acumulators (3) Pilot System Spools This valvle next to control unit over front axe I think this is neutralizer and valvles behind control sticks in cab, also several hoses from all these parts, the thing here is first (when cold) works great, later (now works and dont block) but you need push a bit clutch to realese lift and bucket BTW this is the machine doesnt wants get fixed https://www.youtube.com/watch?v=7RnPHv07cig
I know you have checked the pilot pressure before but have you checked it before and during the failure since replacing these parts? Also do you have the tooling to charge the accumulator? If you do can you check to see that you are getting the full brake pressure. If connected to the fitting the nitrogen goes in to charge the accumulator when engine is started pressure should raise from the 5735 kPa at 90ºC that is the nitrogen precharge point to 13440 kPa at the cut out of the accumulator charging valve. If you are set up with the tooling to charge the accumulator and have the nitrogen to do it I might try draining the accumulator to see if there is oil on the nitrogen side of the accumulator piston. A small amount would not be a problem, like a coffee cup or less but several liters could indicate a internal leak. The way I do it is just connect the hose to the fitting on the top off accumulator and after the nitrogen is vented out start engine and let it run with hose in bucket. You will get air and a little foamy oil then when the piston is at the top it will stop. Then hook up the nitrogen regulator set at the proper pressure for the temperature and keep pumping the brakes till you hear the piston in the accumulator hit bottom then let it set with pressure on it for a while to be sure it is equalized.
well i checked all pressures and are normal, 0 when start problems and 348 when they push the pedal, btw i dont have a kit for nitrogen, what i can do? can i change complete the deposit from the other machine?
Not sure what you can do about checking the accumulator without a way to charge it. At the least you would need the fitting to couple to charging fitting on the accumulator with hose to a gauge rated at around 3,000 psi or 15-20,000kPa then a regulator and the nitrogen tank full of nitrogen. On the cold cooler and hot oil in tank there is a cooler bypass valve, I believe it's located fairly close to the cooler, just follow the hoses from the cooler and they should attach to a valve that works by opening when cooler inlet pressure goes over something like 45 psi. I'd be taking this off and open it up to see if everything inside looks good. No broken springs, plugged orifices or jammed up spools.
About the valvle next to cooler already checked and changed, really this is driving mad
Do the lines going to or coming back from this valve get hot? If not I would be tracing them back to where the start and see where you find things that are hot. I am having trouble seeing where the lines go by just looking at parts book in SIS. But if those lines to and from the cooler are not getting hot either the cooler is plugged inside or there is something blocking the flow or the oil. Can you remove lines from the cooler and check by blowing air through the cooler? I'd blow in both directions and try to watch if anything comes out like a rag or anything eles that could restrict the flow.
How looks the kit for recharge nitrogen? Because now they need push 2 times brake for work
the kit we had at work was an older version of the 1755507 part number, this is the Cat Service tool that goes for around here for about $1,200US It would might be possible to assemble a kit to do this job from locally available parts, might be best to contact local supplier of compressed gases. If you do a Google search online there are several different kits with all kinds of prices. The two most important items I can see would be the regulator to connect to the tank and the chuck to fit the valve on the accumulator. Good gauges and valve capable of the pressures involved also important.
Well tomorrow ,I will try separate the other and see if nitrogen doesn't scape because cat dealer here told me it takes 1 month to arrive the manometers so I will risk myself wish me luck
well guys yesterday i changed nitrogen tank (from the one the other machine had, and a valvle that goes to brake and nitrogen tank, and innsted of getting better, become worst, now they need push brake from beggining even cold, so i think the problen could be the valve, or what you think? btw in pictures from the nitrogen tank, that is what i took out from it
The Cat Dealer does not have the tooling to charge the accumulator? That would be hard to believe as so many Cat machines have accumulators or use the nitrogen suspension systems. Or are you saying to buy a set for your own use will take that long to ship in? Have you tried contacting some place that sells welding and cutting suppies to see if they would have a regulator that was suitable for nitrogen? As that would be the most important part you would need to build your own tool kit. Not familiar with what is available in your area but if there are any industrial supply houses like Graingers or McMaster Carr they should be able to supply valves and gauges sutable for pressures you would be needing. One other idea that maight work would be to take the removed accumulator to the Cat dealer and have them charge it to the correct pressure then return to site and install it. This may not be the recommended way to do it but sometimes you have to do what you can to get the job done. They should be able to see if it had an internal leak doing it this way. Anyone else want to chime in on this thought?? Not having the means to charge an accumulator when owning and using these machines is like not having an air compressor to inflate a soft tire.
Yes ken, sorry I didn't make myself clear, I wanted buy one in cat dealer and is the time for the part arrive, but why the other nitrogen cilinder didn't also worked good, if the other machine was running great? So you don't think this valvle I posted can be the problem
Not really sure but seems like the problem has to be something in the system that is connected to the pump for the pilot system. I guess as a test you could put the one you took out back in to see if this changes the way things work.
Yep, sounds to me like you changed from a weak accumulator to one that has lost all it's charge?
One thing now drive me mad is I took nitrogen accumulator to cat draler , they already chargeed me for make the charge, an they just call me they don't have the tool for charge, in all country, this is insane
Might pay to ask around any local rock quarries, mines, large contractors, somebody has to have the kit to charge accumulators, maybe even a welding supply? They'll at least have the nitrogen and the regulator....
They say manual said is 813 psi but I don't trusht them can you please tell me which is the pressure for that accumulator in psi?
Like lantraxco says: "Might pay to ask around any local rock quarries, mines, large contractors, somebody has to have the kit to charge accumulators, maybe even a welding supply? They'll at least have the nitrogen and the regulator...." I have to wonder how a Cat dealer somewhere in the county could not have even a homemade kit to charge an accumulator! Where I worked we had a kit from back in the early 1970's. I personally adapted it to be able to charge suspension cylinders on Cat haul truck, just an extra hose valve and pipe tee. Also the last full day I worked I used this same kit to charge an accumulator on the hydraulic control for a Nordberg crusher. Also used to charge accumulators on an El-Jay crusher when we had one of those and another time it was used on the accumulator of a hydraulic hammer mounted on a Kobelco excavator. Other than the regulator and the cylinder of nitrogen and a couple gauges the most important part would be the chuck that connects to the fitting on the cylinder. I don't think I have the Cat part number for that but if I can locate it I'll post that information.
Took a little digging but found this: Items 6 and 7 are the chucks, one is for the larger fitting and one is for the smaller, unfortunately I can't be sure which would fit your 988B.
Thanks a lot ken Im sending this info to the "experts" from caterpillar mexico
Ok I have accumulator carged , Monday I go to change again in machine wish me luck, I really hope this fix the problem
Did you find out what the charge was before they brought it up to spec? Just curious.
No lantraxco, i just took out all nitrogen, in the quarry, for be realistic i was worried carrie accumulator in truck with charge of nitrogen
Nitrogen is an inert gas so no fire hazard as long as the accumulator is not flopping around so the fill valve on top gets busted should be no problem. Where did you finally get it charged? Did my posting of the kit information wake up the people at the Cat dealer? "OH! That's what those things are for!" Sometimes dealer mechanics are not that up on things. One time years ago we had a big Allison transmission in the shop and for some reason management felt the need to bring in Allison dealer to replace converter parts. We had done many of the 6000 series but this was an 8000 series other than size of parts identical job. Well Norm and I spent most of the time showing him how to do the job!
Yes I spent all morning yesterday in Cat dealer, showing them how to use the equip and finally I needed do the charge because they dont had idea how top do it, also I checked temp from cilynder and temp from the space where we was located was 25 celcius so i put on it 813 psi, now really i hope with this machine works good, because as always now the client is crazy about his machine, and start say stupid things about my work, so I really hope it works, thanks for the help guys, I will keep you informed what happened
And of course eventos i did 99% of the work they charged me with a 400 dollars bill
Too bad you weren't closer to me in Central NY. I'll bet my ex boss would let me borrow the kit and tank of nitrogen. I'd do the job for free or maybe make you buy me dinner somewhere! I'd even let you ride in the sidecar to get there! Maybe you should ask them for a job, sounds like they could use a few new mechanics!
Well I install accumulator and same, you need push brake for work so I think is the valvle I change the other day, but now started with a new illness, I was trying to make it work push the clutch and I hear a sound like broken hose and stopped don't move forward or reverse, now really I'm sick I don't know what I broke that now doesn't moves please help with that I'm tired and bored
Well this machine is driving me crazy still keep the problem, I'm just thinking why I need push the brake when hot to release power to lift and bucket ? Where the hell is the problem with this machine, also client is making me angry about money (even so far I just ask for my expenses, gasoline hotel, toll post and food )
Seems like you have swapped out just about every component of the system and none have made a noticeable change. The only thing I don't recall you doing anything with is the pump itself. Not saying that is the problem but would be nice if there was a way to test that to be sure. Where I worked we had a flow meter that could be hooked to a pump to check the flow and pressure a pump was putting out. Don't think anyone there these days even knows what that blue box in the yellow cabinet is! To refresh my memory, did you open up the two filters mounted on the inside of the frame on the right side of the machine? I seem to recall the tops having a large socket headed plug in the center and six bolts holding the tops on. The covers are about 4 inches across the flats as I recall. They are, I believe, screen type filters that would catch any big parts coming out of the pumps. Wish I could offer more help but this one is leaving with more questions than answers. One more thought. Have you opened up any of the valves you did remove to install the ones off the other machine to see if there was anything obvious wrong with them. I'd look very close at spools for any small orifices that could be plugged. I had a transmission control valve on a 988A onetime that had a very small orifice with a piece like a small grain of sand in it that stopped the transmission from going into gear.
well guys after many problems, i contacted an old teacher that works in Caterpillar in Illinois, and he told me maybe the problem is located in the brakes and pilot system pump (i never changed that one) can somebody help me with that info, is the one down, because he only sent me this pic,
The procedure referred in the photo above is for removal of the PUMP DRIVE once the Steering & Brake Pump has been removed, not to remove the pump itself. Why did he want you to remove the pump drive..? Did he in fact want you to remove the pump drive..? I am confused. Not difficult I hear you say, but the procedure shown in that photo above bears no direct relation to a pump .........
Nige, that makes two of us being confused as to why he was sent the pump drive removal instructions. If there was a problem with the drive, failed splines or such, then there would be loss of steering at the same time as the loss of pilot pressure. I believe this machine has the Tyrone gear pumps. I know they can get some wear on the end plates that might not be real obvious to some and that will cause a large loss of pressure and flow when warm. Not to mention worn bushings letting the gears cut into the housings.