Losing pressure or power

[Goshenkubotaguy]

I have a unknown age kubota bf350 front end loader on a kubota b9200 4wd
Machine starts up good but after about fifteen minutes the hydraulics have no power. Still has hydraulic drive power in all ranges but for bucket operation it wont lift a bucket of gravel. Try to bury the bucket and push dirt and it starts inching forward then stops like a relief valve is open. Just loses everything hydraulic power wise and makes a straining noise. Any help would be appreciated
Btw. Thanks for allowing me to post. I am a new menber here.

 

[torch]

I am not clear on which hydraulic system is losing power: the front end loader won't lift, or the HST won't drive the tractor? The answers you get here can only be as good as the description you provide. Be detailed and accurate when describing your problems for the best advice.

Is this tractor new to you, or is this a new problem in a machine that you are used to operating?

I am not personally familiar with that model, but generally the tractor hydraulics and the transmission use separate pumps. I believe that loader is connected to the tractor's on-board engine-driven pump that also supplies the three point hitch. The HST will have it's own internal pump.

The two systems share the hydraulic oil. If both are fading as the oil warms up, then I would suspect the wrong oil is in the sump.

If the problem is that the tractor won't push the bucket into the pile, ensure you are in the low gear range, full throttle and don't push all the way down on the HST pedal. It is counter-intuitive, but think of the pedal as controlling an infinitely variable transmission. Pushing it a little bit is akin to selecting a low gear, pushing it all the way is akin to selecting the highest possible gear. You will get more pushing power with slight pedal movement.

Depending on the material you are trying to scoop, wiggling the bucket up and down a bit as you drive forward will help work it into the material.

Tractordata.com shows the lift capacity to be over 1400 lbs. It also shows two bucket sizes were available -- a 50" and a 60". It does not show the actual capacity of each bucket but 1400 lbs is around 11 or 12 cubic feet of damp gravel. Make sure you are not using a light materials bucket to lift heavy material.

It is possible that the relief valve is set too low or the pump is worn out, reducing pressure in the system. The noise you hear could be the relief valve operating. You would need a high-pressure gauge and suitable coupling to check the pressure available. Tractor data shows it should be 1930psi. Because the same system is supplying the 3ph, I would think you would also have reduced lifting capacity on the 3ph if the problem is related to available hydraulic pressure.

It is possible that one or more cylinders are leaking internally. That might also account for the noise you are hearing. However, if a cylinder has an internal leak, you will generally find that cylinder won't hold even an empty bucket, falling rapidly under gravity.

 

[North Idaho Wolfman]

If the tractors not moving properly that has nothing to do with hydraulics.
Movement is controlled by the hydrostat.
I would say you need to start by finding out if you have a fried mechanical clutch, the most likely scenario.

 

[Goshenkubotaguy]

To answer the questions. This machine is new to me. I purchased it used and it has never run perfect since day one. The previous owner had issues with it driving asbit only has low and medium speeds. High gear does absolutely nothing when engaged. I have strictly used low gear around my property because its a small lot and im only filling property.
The hydraulic fluid im using is from tractor supply. Its vp hydraulic tractor oil. They said it woupd work.
My power/ pressure issue occurs in both driving and trying to use the front end loader. Everything is fine until the machine is warm after a bit of use. Then when I tilt the bucket down and try to dig dirt moving forward it moves a bit then wont go anymore. Just squeels for lack of a better term. When trying to tilt the bucket back and lift a load the same thing occurs. It just squeels and strains. Without a load it will drive aroynd the property bit when it comes to having 4wd engaged and trying to dig with the front end loader it lacks all power.
Im comparing this machine to my fathers bobcat which would power through dirt even if there were roots. This machine when hot or at operating temp struggles to lift a bucket of item 4.

 

[North Idaho Wolfman]

The previous owner had issues with it driving asbit only has low and medium speeds. High gear does absolutely nothing when engaged. I have strictly used low gear around my property because its a small lot and im only filling property.

With more information, I'll say it again, You have a fried mechanical clutch disk!

 

[Goshenkubotaguy]

So the fried clutch is whats causing the lack of lifting power as well?? Ive never done a clutch on a tractor how different is it then the clutch on my camaro. Simply unbolting the bellhousing/transmission or is there alot involved. The shops around me dont want to even look at the machine hence why im trying to fix it myself. I was told its to old to invest any money in

 

[torch]

So the fried clutch is whats causing the lack of lifting power as well??

Not if the hydraulic pump is engine driven. But the lack of motive power certainly could be due to a clutch issue and is worth investigating. I wonder if it is possible to see the shaft on that model, to verify if it stops turning when the tractor stops moving and starts squealing.

To change the clutch you split the tractor at the flywheel bell housing. Similar to a car, but you have to support the two halves while you separate them. You will also want to remove the FEL and probably the FEL subframe first. It's not too bad a job if you have a place to work, a decent set of metric hand tools and reasonable mechanical aptitude.

 

[eserv]

Not if the hydraulic pump is engine driven. But the lack of motive power certainly could be due to a clutch issue and is worth investigating. I wonder if it is possible to see the shaft on that model, to verify if it stops turning when the tractor stops moving and starts squealing.

To change the clutch you split the tractor at the flywheel bell housing. Similar to a car, but you have to support the two halves while you separate them. You will also want to remove the FEL and probably the FEL subframe first. It's not too bad a job if you have a place to work, a decent set of metric hand tools and reasonable mechanical aptitude.

If you engage the PTO it will stop turning if the clutch is slipping.

 

[torch]

If you engage the PTO it will stop turning if the clutch is slipping.

Doh! Why didn't I think of that?

 

[North Idaho Wolfman]

Doh! Why didn't I think of that?

That method works on about 1/4 of the Kubota models.

 

[torch]

That method works on about 1/4 of the Kubota models.

Ok now that surprises me. I would not think it worthwhile to go to all the expense and complication of a separate PTO clutch in a compact tractor -- especially one with HST, which effectively makes any PTO a live PTO.

 

[North Idaho Wolfman]

Ok now that surprises me. I would not think it worthwhile to go to all the expense and complication of a separate PTO clutch in a compact tractor -- especially one with HST, which effectively makes any PTO a live PTO.

Yea there are several variations used for a live clutch:
Single clutch disk for drive and PTO, with Mechanical PTO Engagement, GST's and some mechanical shuttles use that design.
Single mechanical clutch for the PTO with drive being direct coupled.
Single clutch for PTO and Drive with Hydraulic PTO engagement.
Direct coupled PTO with Hydraulic clutch, Mechanical clutch for the drive.
Direct coupled on both with hydraulic clutches on both.
And of course Dual dry clutch disks, one for drive one for PTO.

Now the B9200 will have a single dry clutch for both the PTO and drive, not a live design, it's like your B7100.