Hi everyone. When I’m digging my bucket relieves noticeably. I raised the attachment up overnight and this morning the bucket cylinder dropped around 8” of stroke. Is that to much? If so I guess we need to re-seal then? I will go over relief and check to see if she heats up. How long should it take? Thanks
Good day James Bucket cylinders normally have a much higher creep rate than that of arm & boom, as there are no additional valves other than the spool to prevent creep. To advise you precisely, we would need to know the make and model you are operating. Tall buckets and quick couplers make the cylinder more prone to lifting the relief valves. Kind regards Uffex
Bucket should be the strongest component. But for a cylinder to bypass bad enough to act like it is on relief, I would think the bucket would damn near fall instantly. Put some load on the bucket such as a full load of dirt, curl all the way and see what it does. As for heating, 20-30sec on relief should cause something to warm up noticeably.
if you can cap the lines on cylinder with the bucket on the ground and then raise it and see if it drifts will help eliminate the cylinder as cause
Not really. There is a volumetric lock that occurs in a cylinder that is truly capped. However, if piston seals fail, forces are no longer acting on on the piston, they are acting on the rod, which increases line pressures significantly, and can easily push to relief. Another method would be to install pressure gauges on both sides of the cylinder circuit.
Since the carry (curl) relief is suspect, put the bucket nearly open (dump), and with the teeth on the ground, raise the machine. Does it drift the cylinder the other way?
Scooped up a bucket of died and curled up. Dropped about 10” in 1 or 2 seconds then continues creeping but only say 1” a minute.
Ok heymccal. Got it in position. I took a measurement and will check it in a say 1 hour. Thanks
This is a surefire way to check a cylinder, Set the boom down with the bucket like your picture, Take the hose off that goes to the bucket end of the cylinder and cap it, start the machine and on idle close the bucket, a lot of oil coming out of cylinder and it not holding means a trip to the hyd shop. Bob
Thanks Bob. I'll try it right after lunch and report back. The bucket stretched out in dump position dropped 1/8' of stroke in 1 hour.
Sounds like piston seals so far. Personally I would dig a bit and check for cylinder heating. If you have that, that is two failed tests, which is usually enough for me to confirm. Look at what I mentioned above about pressures. This is where you can be fooled. With bucket curled, and a normally functioning piston, we might say you have 3000lb pushing on that piston, say the cylinder is 4" ID, that is 238psi line pressure. Now remove the piston seals from the equation and all forces effectively push on the rod alone. Say that rod is 2", that is now 954psi line pressure. You can see how you can get to a line pressure that WILL open a relief.
Just a thought. The hydraulic quick release is tied into the bucket circuit. Can this come into play here?
Good day Normal standards are to time creep over a five-minute period from the measurements do not seem so bad. Kind regards Uffex
Turned the compost pile for 10 - 15 minutes. Upper part of cylinder is hot to the touch. Lower part just warm. I’ll see what I got for capping off bucket hose as Bob suggested to see for sure.
Started the machine and curled bucket at idle with line to bottom of cylinder capped off and orifice of cylinder plugged with plastic plug. Bucket was moving and I couldn’t see any oil spraying out. I jumped off machine and pulled plastic plug and got a steady stream of oil. I then shut it down and put the plug back in. What’s everyone verdict?
The bucket teeth have to be on the ground so the cylinder has something to push against for this test to work. Bob
If you are going to continue on this path, just curl the bucket all the way, smack the relief and watch her spray!
The bucket was on the ground with arm extended. By the way it’s a 2008 Doosan Solar 340LCV. Serial no. DKHELW50001703. I stuck a clear hose in the orifice and put it in bucket and tried curling again. The flow seemed to increase a bit but I’m not sure. Might have to wait to see if the barrel actually empties out up to the gland. If it does I could start it and try again? Thanks for the help so far.
OK fastline. I was trying to not make to big of mess in front of shop but at least we’ll know for sure. Thanks
Yes let the cylinder empty out then start the test. Bob
You can leave a hose on it to try to catch it. Don't just sit on the relief. Bump it. If oil pukes out, you have your confirmation.
I ran out and started it up at idle and lifted up the boom. The bucket freewheeled curling from the weight of the bucket. The plastic plug blew out and oil sprayed. I put back down on ground and curled to relief with no oil spraying out. I throttled up to around 1400 RPM and tried again with no oil coming out.
Should probably back up a couple steps and review. You say the coupler is tied into the bucket cyl? Also, you mentioned the top of the cylinder got hot. What is hot to you? Like hot enough you don't want to leave your hand on it, or just warm? Was the machine oil warmed up yet? I find this test easiest when cold. The bucket should not uncurl in the time you mention. 10" in 2sec is not acceptable. I will assume your fluid level is up? Power loss anywhere else? Also just a thought on the full stroke test. I usually don't do them because the heat is something I look at with a FLIR gun. I guess it is possible that piston assy seated against something to null the test. They usually have an end-of-stroke snubber on that cylinder.
Fastline. The hydraulic quick coupler for the bucket ties into the bucket circuit back behind boom where the steel line coming off the back of boom changes over to flexible hose. I only ran the machine for 15 minutes so the oil was not really hot. The top of the cylinder was noticeably warmer than the bottom.Not so hot that I couldn’t keep my hand though. That may be normal considering the gland is gernerally a little more towards the top the way I was digging through the compost pile. The fluid was good and power is good on all other functions. I can take a picture tomorrow from the parts book of the gland with packing and post it for you to look at if that helps? Here is a pic of fitting that comes off bucket line and another of where it goes to I think solenoid. I wouldn’t think it has anything to do with h the issue at hand.
Actually, it does. If the Orings on that coupler solenoid are failed, youll get the same symptoms. If you have a -6orfs cap and plug, you could disconnect at piping and retest. And remember, that connection can have a good deal of pressure in it, especially if the bucket isn't on the ground, and neutral.
At the moment I am keying on that drop of the bucket and heat you are detecting. Typically a way I have sources these is to get that cylinder in a bind....in this case a bite it can't handle, and sit on that, on "relief" for a 30sec or so. The heat you are looking for will be where the piston is. If you can detect heat around that area, it needs opened up. I don't care about other tests. You can sit on 200psi or 20,000psi, there should not be a hot zone right where the piston is. That means oil is sneaking by, causing massive heating.
I’ll grab a thermal heat gun and a second person to recheck the cylinder and then cap & plug the solenoid line and retest. Thanks heymccal and fastline.
Good day Attached are the creep values for a bucket cylinder maybe helpful fluid at tempreture measaurement in milimeters over a 5 minute period. Kind regards Uffex
Right On!, Thanks uflex.
I’ve run a test on temperature of cylinder. So far there is a differential of about 3 degrees Fahrenheit between bottom and gland area.
Ran another temp test a little longer than last ( 3 - 4 minutes ) and got 4.5 F difference. Capped off hydraulic quick attach and tested with same results. Bucket full of dirt curled in dropped the same 10” or so in a second or so. I’ll wait for further comments and suggestions before I proceed.
Looks like there are a few o-rings; seals and stuff to change. If that’s where we end up.
What was the temp?? You are not looking for differential temps top to bottom. When I said FLIR gun, I mean a thermal imaging camera. I realize not many people have one, just saying. if you let everything cool down, then fire machine, dig bucket into something it won't dig so it is on relief. Note where the piston likely is, sit it on relief for 10-15 sec or so and check for heat on that cylinder around the piston area. On a cold machine, there should be no fluid moving in the cylinder and it should not heat up because the relief should be happening in the valve block. If you want to use your IR gun, do this test, then just comb up and down the cylinder barrel a bit to see if there is a hot spot. Remember there is a lot of steel there so getting instant thermal response won't happen.
Fastline. The temp was 54.5 F where the piston was and 50F at the bottom. It was raining and about 50F when I did it. I ran the test longer on account of weather conditions. Not sure if 10 - 15 seconds is long enough but I’ll try again. Thanks
Rain is not helpful here. If machine is dead cold and you get heating in the cylinder, there is a problem! I agree, if 10-15sec is on the light side but you will be making heat at the valves for sure. Your issues, at least to me, are pointing to that cylinder, but I can understand wanting to confirm a bit more.