Hi everyone, I'm running a 955L, and I seem to have lost all bucket controls. The machine still drives as it should, but I'm not getting anything from the boom and bucket . Any ideas what the issue could be? Thanks
Is there a pool of oil somewhere? Is the hyd. reservoir full? Did/does it make any strange noises before or after it quit? Did it work one day and then the day next day didn't? It really helps to give some history on how the problem developed. If the reservoir is full and it's not making any weird noises I'd guess it's a pump problem. If I recall a 955 uses pucks in the coupler from pump to the engine. I'd look there to make sure the pump is turning. Other possible problems could be a collapsed suction hose or something got in the reservoir and is plugging the intake. I'm not sure if the pump shaft has splines or not but that could be a possibility or the pump is just worn out.
Thanks for the prompt reply mate. As far as I'm aware there weren't any strange noises, although I will have to confirm this with the operator (machine is way out in the Bush in an area with very patchy cell reception). It was working fine one moment, then all of a sudden no controls. Hydraulic oil was at the recommended level, and no serious leakages. I'll get down to checking the hydraulic tank and filters tomorrow. How would I go about checking the engine-pump coupling? Thanks again
It would be good to have a Serial Number for confirmation, but they all look pretty similar. The pump (Item # 14) is gear-driven off the front RH side of the torque converter housing. See illustration below
did bucket drop fast a hard had a 951 break a shaft have had spine to wear out , check to see if you have any presser.
Machine serial number is 43V14380, 3304PC engine. So the filters and tank are clean, next step is checking whether the suction pipe is actually taking oil to the pump. However I'm told the pump is not making any strange noises, so I doubt it's oil starvation. Tried disconnecting one of the hydraulic hoses on the ram and no hydraulic pressure there. I'm at a bit of a loss to be honest, as the machine has worked perfectly without any issues at all for the past 8 months or so.
That's the engine serial number. Need the machine serial number. Do you mean no pressure or no oil?
Sorry, my bad. 955L - 57M0747 So it's not shooting out any oil from the ram pipes when you try and operate the controls. Thanks
Update: the hydraulic pump splines are good and the drive from inside the torque converter housing is good as well. Any ideas as to what else we could check?
pump shaft turning pump mine broke like cut with saw, right in side pump, was victors pump.
i assume you must have had the pump removed to make those checks. I suggest CAREFULLY remove the pump end plate and check for a broken shaft. Also check for a blocked pump suction line.
Pump suction pipe is supplying oil as it should, but when the outlet pipe is loosened, there's just a trickle of oil coming out. Unfortunately it does seem like the shaft is the culprit (I was hoping for a less expensive problem like the relief valve or something lol). Machine is about 200km from civilisation so I'm going to get the pump removed and brought to the yard and I'll open it up and have a look. Again, thank you very much for all the excellent info and assistance, and I'll give you guys an update once I have the pump. Cheers
Are you sure the reservoir is full? Loosen the intake pipe and see if oil is coming out. I don't know if it's possible the cap on the reservoir is faulty and not venting which won't let the pump work. I had a faulty fuel cap on my skid steer and it wouldn't get fuel. Maybe the same type of thing could happen with the hyd's?
Yes the reservoir is full and the intake pipe is bringing oil down to the pump. I'll ask them to give it a shot without the tank cap and see what happens. Cheers mate.
If it's a vane pump maybe the vanes are worn out? Knew a guy that always kept a spare cartridge for his excavators with Vickers vane pumps.
If that's the case, how much do you reckon a replacement cartridge would cost? Because my local Cat dealer (Mantrac) would probably charge me more than the machine's worth based on previous experiences I've had with them
Not even sure what model of pump it is or if it uses a cartridge with vanes. I think you should follow Nige's instructions above and remove the end plate to look for damage.
Pressure relief valve stuck open?
That's what I thought (and hoped for) initially, but the pump outlet is not bringing hydraulic with any pressure when the outlet pipe is loosened.
Vane pumps will snap shafts and break vane housings Costex shows cartridge for $199 Cat $1000
Do Costex ship to Kenya..? Because that’s where the OP is.
Update: I've just recieved the pump from site, and the shaft is perfectly fine. I can see it rotating till the back, and it's making reassuring squelching noises when I rotate it by hand. So that's a relief. Question is, if not the pump, then what else can I check? The operator has just now mentioned to me that he heard some humming/buzzing sound from inside the hydraulic tank. Does this indicate a pressure relief valve issue, and if so, how do I go about checking it? Thanks
From the way you are posting I get the impression you are working on second-hand information supplied to you from the site. Somewhow I think someone is not telling you the whole truth. Maybe it's the truth as they see it, but there appears to be gaps in the supplied information. For example:- 1. Suction line to pump is supposed to be full of oil - inpression is that oil is flowing freely to pump. 2. Nothing much coming out of pressure side of pump when engine is running. 3. Pump seems OK (no broken shaft at least) when received at workshop. Who else thinks like me that there is some pertinent information missing here..? I think I'd be cranking up the pickup and heading out there for a look-see with my own Mk1 eyeballs if it was mine, even if it was a signficiant distance.
You're exactly right, I'm working with some not very reliable second hand information. I am going to make a trip down there definitely though, and it's very annoying because I feel like it's going to be something quite minor at the end of the day. I'll be honest I dont have too much experience with hydraulic systems, but I'm learning on the job. When I get there, how would I go about checking the whole system, especially the valves? Any information here would be really invaluable in helping me prepare, as when I get to the machine, theres no cell reception, or any sort of tools or spares apart from what I take with me for absolutely miles around. Thanks again.
Not all operators will admit all the details when something breaks. Like, I heard a noise so I drove the machine to the shop... and it died on the way. I heard a noise so I shut the machine off immediately would be the better response but if the machine is half way between the job site and the shop it's not likely is was shut off right away.
Here's what I suggest for troubleshooting (*other opinions may well be avaiable) In the hydraulic system the oil starts its journey from the tank. From that same point you should start your diagnostic journey and, instead of the old saying "follow the money" - you should follow the oil. Whatever route the oil takes starting from the tank, that is the same route you should take on your diagnostic journey. Assume nothing, believe nothing. Check everything using your own powers of observation. Disassemble and inspect as necessary, but work in a logical sequence in the same direction always following the oil flow. Attached are the documents for the System Operation and the Specifications for the hydraulic system. They should be of some use. I'll see if I can find the Test & Adjust also. However I think your problem is much more basic, like for example possibily something as simple as a plastic bag blocking a suction pipe somewhere. Believe me I know what you're up against. I spent a number of years in the Southern African bush in a former life.
Thank you so much Nige this is brilliant information! I'll give it my best shot and hopefully get it running before the rains wash us out! It's absolutely brilliant working in the African bush isn't it? Its mental how frustrating it can be at times, but I just love it for some reason. Again, thank you everyone for taking the time out and all the valuable info.
I think they do they have a list of country's a mile long
Yep I had a customer who had a engine lock up his operator said it was full of oil when I tore it down it had two layers of oil a thin layer of black oil and the rest was new unused oil
have you pulled the pump apart
He filled it with oil after it died?
No I haven't pulled it apart yet. It does seem okay to me, although I'm going to get someone more experienced to have a look at it today.
yep
I’ve seen that too. "Who, me..? No, it was nothing I did. It just quit." Operators sometimes aren’t the sharpest knife in the box. Thing was back in the day they could (somewhat) get away with stuff because with only analogue gauges the machine couldn't tell on them. Today with electronics recording everything it's next to impossible but that it still doesn't stop them trying though.
yes some time it would be good for eq to have cameras so you could see what people were doing to mindless eq. some time there is more to it than we think.
I think some of the newer equipment will tell you if you know how to retrieve it.
Update: Made the trek down to site today. Upon fitting the hydraulic pump, the bucket tilt operation was working sporadically, but there was nothing on the lift cylinders. I could hear a humming sound in the tank when the controls were operated, so we drained the tank, opened up the side cover, and found tiny pieces of o ring. Opened up the main pressure relief valve, and turns out the o ring between the dump valve and the pilot valve had failed. Had a generic o ring set on me , so I replaced it just to see what would happen. Worked perfectly...for about 5 minutes and the crappy o ring went. I'll need to source the kit from my local dealer, but it seems like at least now we know what the issue was. Couldnt have done it without all the brilliant info and suggestions here, and especially the hydraulic system documents that Nige sent, absolutely brilliant.
We depend on Nige to clear the smoke and find the numbers.
Glad you got it figured out. It's always easier being there in person.
Agreed. That way you don't have to depend on second-hand information.
Update: So I got the o ring from Mantrac, fitted it and again, the machine worked for about 5 minutes and blew the o ring again. What could be causing this?
have you checked pressure maybe the relief valve is stuck
I'd suspect there are no pressure gauges on site. Maybe just better to disassemble the relief valve and inspect/clean it
Yep no pressure gauges on site unfortunately. Let me give it a shot, as when I replaced the o ring I only went as far as removing the pilot valve and the dump valve spring, but from the diagrams, the dump valve has another o ring right at the end. So could it be a case of that o ring having failed, which led to this one failing? Unfortunately I've already come back from the site, and I dont really trust anyone there to do this, so it'll mean another trip back down. Oh well.
If one O-ring was bad it's likely the other one is too.
Update: I disassembled the entire control valve assembly, checked all the valves and the o rings, replaced the relief valve o ring and put the assembly back in the tank. The machine worked perfectly for about half a day, then I get a call saying no controls again! What could be causing the relief valve to behave like this?
I think the valve assembly while it looks good, it has to much wear so the O rings keep blowing.
Yes the machine has done a fair bit of work over the past few years so I wouldn't rule out wear. Another thing I noticed was the clamp for the master valve actuating rod on the tilt cylinder is broken off, so the actuating rod is no longer there. Just changed operators a couple of months back, so no one can tell me how long its been that way. Could that be an issue, or somehow related?
Are you talking about the return-to-dig rod? It shouldn't matter as long as the bucket stays where it's set manually.
Yes that's the one. Okay fair enough just wanted to rule that out, thanks.
Update: Took the relief valve out, turns out it was stuck open. Freed it up, cleaned it and put it back in. Machine's been working for about the last half hour or so without any issues. Question is, what could cause the relief valve to keep getting stuck open? The o ring fitted earlier was fine, but it was just stuck open.
Any signs of scoring on either the relief valve body or the plunger itself.? Did the plunger feel "sloppy" in the bore.? I'm wondering if there is wear that is allowing the plunger to "cock" sideways and jam in the bore. Did you take any photos of the parts when you had it disassembled.? Photos are always good. I understand the difficulties of uploading them when you are out in the field but they could be uploaded later when you reach a location with better internet.
Unfortunately no photos, as I didn't really expect it to work to be honest, it was just one last shot out of exasperation. I left the site and the machine did a good whole day's work, and now its started acting up again. I cant even go back as they've banned inter city travel here cos of the virus. I did however manage to get hold of a complete tank off of a scrapped 955L. It's plumbed for a ripper and multi purpose bucket as well, which mine doesn't have. So the plan is to blank off the outlet ports for the accessories and send the entire tank to site to be fitted (if I can get a lorry through the lockdown roadblocks). Hopefully this sorts out the issue, and once the machine comes back to the yard, I'll bolt on a ripper and fabricate a multi purpose bucket out of an old dozer blade I have. I think the jamming must be due to wear, although I can't say it felt sloppy in the bore. I've asked the Mechanic on site to try and free it up again, so that way at least we'll get a bit more work out of the machine before I can get the replacement tank to site. Btw Mantrac quoted me $3200 + 1 month waiting time for a new relief valve.