Slack in FEL dump circuit

PaulT · Nov 28, 2001

I recently noticed that my 402 FEL has play in the dump rams after the tractor sits for a few hours. This never happened before. I got the 2710 in May and have used it often over the summer. I only noticed it about 6 weeks ago. If the bucket is off the ground, after a few hours, or overnight, I can rock the bucket back and forth with my hand. The rod is moving in the cylinder and all the pins/bushings/etc. are tight. Starting the engine and rolling back the bucket tightens up the hydraulic circuit, and it doesn't slack up again while I'm using it. It really isn't a problem, but I'm curious why it just started recently. I haven't noticed any leaking aroung the ram seals. Any thoughts??

PaulT

Mike_Dumond · Nov 28, 2001

Paul, you may not be leaking fluid out, but you may be sucking air in. Check the fittings, and always park with implements lowered. That way, neighborhood kids can't accidently lower them on their friends.

Keep the greasy side down.
Mike

Bird · Nov 28, 2001

Paul, mine does the same thing (I assume you're talking about with the engine off). I don't consider it anything unusual or important. When I start the engine and move the bucket that takes the slack out of it. Hmmm . . ., of course you're talking about leaving the bucket off the ground and I don't do that. When I park it, I let the bucket down, and when I park it overnight, I not only let the bucket down, but then move the joystick in all directions after killing the engine to relief any pressure in the lines. So maybe I wasn't comparing apples to apples here./w3tcompact/icons/wink.gif

PaulT · Nov 28, 2001

Bird,

I, too lower my implements at the end of the day (box blade/FEL) and release the pressure in the valve. Its just that sometimes I shut off the tractor during a project while I use a rake or shovel for a while/w3tcompact/icons/shocked.gif! It happens in either case, as long as a few hours have gone by. Sounds like we have the same symptoms. Did yours always do this, or did it happen sometime after you started using the FEL? I think I must be sucking in some air somewhere to get the play, and using the curcuit purges any air that has entered. While I don't think the air in the system is a problem, I think the location of the air leak (if it is a leak) could be - seals or something that someday will leak fluid out instead of leaking air in. The fittings are all tight. Could the quick-disconnects be the culprit? They don't leak fluid under pressure, so I don't think they would leak air when pressure is released.

PaulT

Bird · Nov 28, 2001

Paul, I'd be afraid to say for sure, but I think mine has always done that, and I believe the one on the B7100 did, too. I've just kind of considered it normal. Another thing I've found is that the first time you start to curl the bucket back, when it hasn't been used for awhile, is that it may "dump" forward an inch or two first before starting to roll back. So if I intend to move something where small increments are critical, I always move the bucket both directions first.

Joe_W · Nov 28, 2001

My 2910 started doing that recently while I was using it. I have over 200 hours of hard work on it since I received it on June 8th of this year. I first noticed the looseness while driving over rough ground with the bucket empty. I saw the top of the bucket jump up and down with the bucket in a mid-curl position. I locked the brakes, got off the tractor with it running and was able to move the bucket up and down very easily by hand at least 4 inches. I noticed that the curl cylinders would move about an inch in and out when I did this. I checked the pins and they seem tight, and the fittings have all been greased regularly. When using the loader all seems to work as normal, so I haven't given it too much thought. When I first got the tractor I went through some leakage at the couplings on the control valve, but those were repaired with new o rings and I have not seen any leaks since then. Maybe Kubmech can shed some light on the situation. If there is a problem, now would be an ideal time for me to take it to the dealer, as we are ankle deep in mud right now.

Joe W.

bcarter · Nov 28, 2001

Paul,

I've got the same set-up and the same symptom. Can't say that its always done it but I certainly have noticed it recently. My bucket teeth stick up a little when the loader is on the garage floor - If I step on the teeth (which sometimes happens as I try to sqeeze around the bucket when the garage door is closed) the bucket will move a little.

I was starting to wonder as you did if this was normal or not. Given that more than a few folks seem to have this problem, its starting to look that way.

Bill

Youare · Nov 28, 2001

I have a Kubota L3000DT with FEL with about 30 hours on it. I noticed the same thing with the bucket sitting on the floor when I steped on it it rotated very freely. I have even noticed that when the tractor is running I can take the edge of the bucket and rock it by hand. When I used the front edge of the bucket to back drag some dirt once a little down pressure made the bucket roll. I didn't think this was normal but thought it may need time to break-in.

All my other hydraulic experience tells me that you can't compress a liquid and if the valve to that side of the cylinder is closed it should not allow the rod to move in te cylinder. Then I thought maybe there was some type of relief valve in the line to prevent damage. I would like to know what is normal.

Randy

kubmech · Nov 28, 2001

Slack in the hyd. circuit after sitting is normal. You're looking at a few combinations of things that will cause this. Hot fluid cooling over a period of time as well as normal leakage in the circuit (esp. when cool) Cylinder seals are not perfect and do bypass slightly (very slightly) the loader control valve spool is just a metal to metal seal and will bypass over a period of time. It does'nt sound like you have anything to worry about.
As far as play in the bucket while in use, some of you have 3 position loader valves and some of you have 4 position valves. The difference is (on the newer machines) The 3 pos valve has a regen circuit which is always activated in dump, while the 4 pos valve only activates regen in the far right detented position. If your not activating regen during the dump cycle you will have play in the bucket cylinders.

PaulT · Nov 29, 2001

Thanks, Kubmech

I'm sure I speak for everyone here when I tell you how fortunate we are to have a bona fide Kubota mechanic willing to provide free consulting and advice. If you ever make it to upstate NY, I've got a hot meal and a cold beer with your name on it - its the least I could do. Its people like you willing to contribute your knowledge that makes this site so great!

PaulT

Bird · Nov 29, 2001

I'll second what PaulT said./w3tcompact/icons/smile.gif

Joe_W · Nov 29, 2001

Thank you very much Kubmech, I'll sleep better tonight knowing I'm not tearing up my tractor. Best wishes for the holidays.

Joe W.

kubmech · Nov 29, 2001

Garsh guys /w3tcompact/icons/blush.gif thanks......

Don_Curley · Dec 16, 2001

I know I am late to this thread, but I have to also add my thanks to kubmech as well. I noticed these same disconcerting developments on my B2910's 402 FEL (after about 20 to 30 hours of use), and I was sure I had overly abused something. Whew, am I relieved!

Don

PaulT · Dec 17, 2001

New development - I noticed after looking closely on the garage floor that there is a very moderate leak around the right hydraulic ram for the dump action. It probably leaked a 6 inch spot in about 2-3 days. I wiped off the cylinder end so that it was dry, and used it. After putting it away again, it was still dry (about 2 days of weekend use) so it didn't seem to leak under pressue during that period. Now that it has been sitting again (for about a week), there is a spot again and the cylinder end is wet again. Why does it only seem to leak when it sits, and not when its under pressure? I would think if there was a leaky seal, it would leak more under pressure. I have a mail order machine, and I don't really want to test the waters now for warranty work if I don't have to. Any ideas?

PaulT

kubmech · Dec 18, 2001

Paul, it sounds like what you have is a gland seal leak. Many times this seal will leak static but not with sytem pressure, due to the "umbrella" design of the seal it seals better under pressure than when sitting static. I would'nt worry about warranty due to mail order. The loader should be covered for one year from date of purchase. Kubota will have a record of your warranty date and any dealer should have access to that information. Take the cylinder off and take it to your local dealer with model and serial number of the loader and tractor. It should be covered as long as there's no nicks in the rod.

kubmech · Dec 18, 2001

Oh yeah, one more thing, on a few 2710's or was it 2910's I don't remember. We had a problem with bucket cylinder bracket alignment, which caused preload of the bucket cylinder. If your machine has this alignment problem it will cause premature failure of the cylinder gland, gland seal and possibly the rod. When you pull the pin on the bucket side of the cylinder take note if it's preloaded or not. Most likely angled to the left as viewed from the front of the machine.

PaulT · Apr 9, 2002

Kubmech,

Thanks for your diagnosis. Its been a while since I posted my problem (end of Nov.), but I'm glad I waited (procrastinated)/w3tcompact/icons/blush.gif before I finally got around to taking the cylinders to the dealer. Sometime over the winter I noticed that the left one stopped leaking and the right started leaking, but the lack of pressure was still there. When the bucket was on the floor, I could step in it and rock it just with my light body size/w3tcompact/icons/wink.gif. I finally tok both cyclinders to the dealer, and he fixed me right up. Thanks to Kubmech, I told him I thought it was the gland seals, and he agreed. He replaced them, but Kubota needed him to send the defective seals back, since they believe they had a "bad batch" of cylinders a while back. Apparently there is a groove for the actual gland seal to sit in, and the inner diameter of the seal was a larger diameter than this groove. What that means is the seal never actually touched the cyclinder ram, but was just "hiding' in that groove. I suggest that the rest of you that have noticed any similar problems check with your dealer regarding the "bad batch" of cylinders and thier gland seals.

On another note, this was my first visit to my local dealer for warranty work. Since I didn't buy it there, I was a little nervous about how I would be treated. After providing evidence that I did, in fact own the tractor, where I bought it, etc. They treated me like royalty. Said to be sure to call him up if there was ever anything else he could do for me. Great!!/w3tcompact/icons/grin.gif CaseKub3 - Pete, if your reading, 2 things - Register on TBN, and tell Bob once again what a pleasure it is doing business with him.