Go BottomBucket Won t Raise Tractor High Enough for Mower
 | Skylark
Join Date: Posts: 1 
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2003-04-26 53805
Last winter when we removed the midPTO mower, we used the bucket to lift the tractor high enough to remove the mower, enabling us to slide it out from under the tractor. Today when we tried to put the mower back on, the tractor won't lift. It lifts up about an inch then fails. The only thing we have changed since last winter was we slowed down the speed at which the back PTO moves up and down. That's it. What would cause the the tractor to suddenly stop being able to raise itself off the ground? And if it is the relief valve kicking in, why all of a sudden is it kicking in now and how do we remedy this?
I should add we did check the hydraulic fluid and it is fine.
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 | WillieH
Join Date: Feb 2003 Posts: 543 New England 
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2003-04-26 53807
What model tractor are we referring to, and is it a hrydostatic?
Willie H. ....
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| Skylark
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2003-04-26 53809
Yep hydrostatic and it has about 400 hours on it (very good condition) and it's a '96 B7100 HSD ....
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 | DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada 
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2003-04-26 53816
When you figure it out let me know. About one time out of ten my BX does the same thing, just will not lift the front end. ....
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| RichT
Join Date: Jul 2003 Posts: 33 SOCAL
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2003-04-26 53821
Mark, my BX22 FEL will lift the front end every time. If I use the FEL and backhoe in tandem, I can get the entire tractor airborne (carefully). ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2003-04-27 53834
I imagine it's the flow control valve on the 3ph that was slowed down and that shouldn't affect anything else. I'm assuming that it's the loader lift rather than the bucket that was used to raise the tractor and that the problem is still there. I imagine the oil level was checked. I don't know the tractor but I'm assuming that if it has power steering it's fed from a separate pump rather than a priority valve.
Here are some questions and quick checks that might help sort out the problem. Does the 3ph lift normally? Is the lift down-pressure the only function affected (in other words, does the loader lift and the bucket have normal power)? If the loader lifts with power, will a heavy load stay up?
If the bucket works OK, you might try swapping the lift and bucket hoses at the valve assembly to see if the problem moves to the bucket. If the lift leaks down under heavy load, you might disconnect the lift cylinder hoses to see if the leak-down stops. If there's any doubt about the condition of the oil, screens and filters, I'd change them. If the tractor has a diverter valve, I'd check to see that it is fully in the auxiliary system position.
A bad system relief valve would affect all hydraulics so if some hydraulics are working normally that's not the problem. Many valve assemblies have their own reliefs for each circuit. Swapping valves should identify that and other problems with the control valve. The leak-down test with hoses disconnected would identify a cylinder with seriously blown seals.
....
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| Skylark
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2003-04-27 53861
>I'm assuming that it's the loader lift rather than the bucket that was used to raise the tractor and that the problem is still there
correct
>I imagine the oil level was checked.
Yes
>I don't know the tractor but I'm assuming that if it has power steering it's fed from a separate pump rather than a priority valve.
Doesn't have power steering.
The bucket works properly up and down. Haven't had a chance to check it with a full load to see if it will stay up lately but it did a few weeks ago as far as I could tell.
>If the bucket works OK, you might try swapping the lift and bucket hoses at the valve assembly to see if the problem moves to the bucket
Sounds like a good idea, I will see if my husband can figure out how to do that....he's a newbie with this stuff but he did dissassemble and reassemble the relief valve this morning. We were thinking that maybe that valve is kicking in when we try to lift the tractor with the bucket and maybe just needs an adjustment? (this goes back to a problem we had over the winter with our back blade (see: http://tractorpoint.com/cgi-bin/tractor/fullThread.pl?parentnum=48125&catname=Kubota%20Owning/Buying&catcode=KU#49087)
where the back blade would suddenly not lift unless I moved the front bucket a few inches an then it would lift fine for awhie, and then quit again. This problem is also happening with the mid-mount mower since it's connected to that hitch. I wonder if the problems aren't related and it's merely a relief valve adjustment?
in any event we ended up driving over the mower to get it attached as it needed to get attached. ....
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| DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada
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2003-04-27 53869
I figured out what the problem was with my BX..... me.
I expected it to lift the front end anytime I pushed the boom all the way down, but it does not have enough travel with the bucket curled up to do that.
I have to put some 'down' curl into the bucket cylinder so the boom can raise the tractor.
Silly me. ....
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| Skylark
Join Date: Posts: 1
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2003-04-27 53884
I had the downcurl...we even put a block under it and that didn't work. It starts to raise and then it stops. ....
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 | jeff r
Join Date: Jul 2003 Posts: 428 burton. michigan
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2003-04-28 53888
You need to increase the relief valve pressure. The adjustment is in your front loader controls.....screw it in and then tighten the jam nut. ....
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| Skylark
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2003-04-28 53892
Jeff, this is what we've been thinking, we just need to pick up some shims. The relief valve that we found however is not in the front, it's near the hydraulic cylinder in the back by the seat...or is there another one?
Out of curiosity why would a readjustment even be neccessary when it was working fine a few months ago? ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2003-04-28 53894
A relief valve certainly is a possibility. There may be two of them--the tractor's system relief and one on the load valve as well. Either of them could be the culprit. Normally a pressure gauge would used to adjust them to ensure that relief pressure is within spec for both the tractor and loader. Relief pressures that are too high may cause problems.
I had a few similar problems when I first got my used 1710. The problems were infrequent and mostly the 3ph wouldn't lift, but several times a loader circuit was affected as well. I found that the problems went away if I jiggled the loader control valve handles. A joystick doesn't have convenient handles to jiggle but if it has a joystick, I might start wondering about the linkage. My problems went away after I changed the hydraulic oil, or maybe my operating technique just got better.
I guess the problems with the rear lift remain and they may well be connected with this problem. In the open centered hydraulic systems that virtually all CUT's have, control valves are plumbed in the high-pressure line in series and ordinarily the 3ph is the last valve in the series. Operation of a control valve cuts off the oil flow to down-stream valves. A cylinder stops moving when an upstream valve is operated, or it may move only as long as the upstream cylinder moves, depending on the type of loader valve.
I wouldn't forget about relief valves etc. but I think I would jiggle the control valves or joystick to ensure the valves are centered. I'm not sure how I'd check a joystick linkage. Maybe somebody has a suggestion. If the lift jumped but neither moved up nor down, I'd check the line quick-connects. You also might increase engine rpm to see if that helps. ....
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| WillieH
Join Date: Feb 2003 Posts: 543 New England
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2003-04-28 53906
Skylark -
Question:
When was the last time that the Hydraulic Filter was changed? When was the last time that the Hydraulic Fluid was changed? At what engine RPM are you trying to raise the orange? If RPM's are too low, insufficient hydraulic flow will result and not allow the tractor to lift,ie: the pump is not turning fast enough to deliver an output sufficient to satisfy its demand. If inadequate fluid, you may have a partially plugged line. If the filter is dirty, the pump will ultimately be "starved" from hydraulic oil and cavitate, spin free basically without the ability to displace output to the hydraulic circuit, and ultimately not be able to work under load. Not only is this detrimental for the pump, as it is running dry, however, if the filter bursts, the debris from the filter will continue downstream throughout the tractor's hydraulic circuit.
Nine times out of ten, the culprit is not something deeply involved, as much as something quite elementary, that we simply forget about.
Although relief valves do occasionally malfunction, they usually require a pressure gage for proper readjustment for proper working pressures within the system.
It seems rather strange that this valve needs any sort of adjustment with only 400 hrs on it. That is pretty low run time for a relief to malfunction.
If this valve, the FEL relief valve,or any other, is adjusted, therein lies a potential for failure of another component of the system if not properly done, not to forget potential for excessive hydraulic pressure build up that could result in severe injury.
If you have had the hydraulic fluid and filter changed, which is recommended every 100 hours of run time, are we sure that the proper amount of fluid was installed? You must run the tractor for a period of time, usually about a half hour, and if equipped with FEL, cycle the FEL to circulate out any and all air pockets to prevent a "bubble" within the hrdraulic system. Then recheck fluid level and add more if necessary.
Willie H. ....
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| Skylark
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2003-04-28 53927
Willie, the fluids were all changed just before we bought the tractor, by the dealer. So I'm hoping that was all done right! But we figured out how to raise the tractor! Two things were going on. We have a floater that kicks in when you push the lever all the way so you can landscape without digging up the ground. You feel and hear a click and that initates the floating mechanism. Second, you put the bucket flat first, make sure the brake is off, and start rotating the bucket to it's upside down position and as you are doing that the tractor is lifted right up. If we put a 2x4 under the bucket it goes even higher. So problem solved. That was a human malfunction!
The business of the back 3ph not wanting to raise now and then is not solved. But our get around is to move the front bucket when that happens and voila, the hitch rasies whatever implement is attached (back blade or mid mower.) Maybe we should just take it into the dealer for that. Sounds like messing with the relif vavle for inexperienced people is not safe. In the meantime we use the get around.
Thanks everbody for all your collective wisdom! ....
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| Skylark
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2003-04-28 53928
Tom G, thanks for the sage advice...we will try the jiggling and line quick connects. ....
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