Frustrated friend with 7500HST, hydraulic issues..

[DavidVT]

A friend (who steered me down the Kubota path) is becoming frustrated with his 7500HST. He is not into the computer thing and asked me to see what the forum might have to say....

1 The loader valve has vibrated since delivery and never been resolved since then. Nuisance but nevertheless a problem.

2 He complains the loader valve will 'stick'. I watched him curl the bucket and lift the bucket at the same time. When the curl came to the end of it's range and stopped, the lifting action stopped at the same moment. IS THIS NORMAL?

3 He also complains that the reverse speed has dropped way off from the original.

The hydraulic level in the tank seems to jump around but is full with the loader fully down and tractor not running.

The tractor might have 100 hours on it but has just gone out of warranty technically. Although having gone in twice for these hydraulic issues during warranty without resolution is an issue...

Thanks in advance for any thoughts...
David in Vermont

 

[seapea]

</font><font color="blue" class="small">( 1 The loader valve has vibrated since delivery and never been resolved since then. Nuisance but nevertheless a problem. )</font>

When I test drove the B7610, I noticed the loader valve vibrated a lot when idling. I think it was actually the plastic housing doing most of the vibrating. I had idled the engine so I could talk to the dealer, and found my self constantly grabbing the plastic housing because the rattling was making so much noise that I couldn't hear the dealer. The rattling noise negatively affected my ability to hear him a lot more than the engine noise did.

 

[KennyV]

David, Hello…
Since seapea took #1… I’ll try #2, Yes that is the way it will work. Your 3430 should be the same. If you divert all the hydraulic to a valve that can not feed anymore oil to a cylinder you will have none left for the power beyond to feed other things downstream… If he had tried to operate his 3point at the same time, he would have found that the 3pt, and any aux hydraulic remotes also would stop. You only can do so much with the available hydraulic oil flow, and once you stall a circuit up stream everything downstream will have no oil to feed their circuit.
Someone with a HST can take a shot at #3… I have a GST with a cab... it's nice and quiet in there. /forums/images/graemlins/cool.gif KennyV

 

[ronjhall]

#1 & #2 have been answered.
I'll give #3 a try.
No my B2910 there is a stop screw that controls how far the HST pedal can be depressed. Adjusting this screw should allow tractor to reverse faster. There is a similar screw for forward. Both are under the floor board near the HST pedal linkage.

 

[_RaT_]

#1 is probably typical on many tractors and is typically lessened once you go just above idle.

#2 sounds like operator error. I had to think about what you were talking about. If I understand it correctly, he has bottomed out one set of cylinders, continues to apply hydraulic pressure to them all the while still applying hydraulic or at least attempting to anyway to another set that has not reached a maximum extentsion. (simaltaneous bucket retract and loader lift or joystick at the 7:00 or 8:00 position). The reason I had to think about it is becasue it seems so natural for me to stop applying pressure to the max'd out cylinders I do it without thinking, literally so it was not apparent what the problem was. He needs to work more with the loader. He has 100 hours of experience on this tractor, how much with the loader?

#3 it's the HST. Have the pedal checked and the linkages that it uses to control the various levers that ultimately control fluid flow through the HST.
Whether the loader is up or down will make no fifference on the level in the tank since oil is in one side or the other of the piston. Granted the hyraulic cylinder rod displaces some oil, but the oil reserve is great enough that it will not show a difference on the oil level. With the engine on or off, the level is the same as well.

 

[Devildog]

I dont know if this will help but on question #2 On the b7500 I used to have when operating the bucket it would stick a little but I realized I was pushing it up to far and clicking it into the free float mode.

 

[btolle]

</font><font color="blue" class="small">( 1 The loader valve has vibrated since delivery and never been resolved since then. Nuisance but nevertheless a problem. )</font>

Technically, it is not the valve rattling but the valve operator (handle) and that has been an issue with severa folks on various models. Do a search on "rattle" and you may find some posts about how people cured it. Basically it involves putting some shims in a few places to tighten the handle up a little.

I'll bet you could take a small piece of foam rubber and stick in the middle of the mechanism and stop 80% of the rattle as a temporary fix.

My B7100 handle rattled a lot, the B7510 rattles, but quite a bit less. I've learned to ignore some of the odd noises machinery makes. This is, after all, a tractor, not a Mercedes Benz.

Bill Tolle

 

[techman]

One more thing, it is just a bit of experience, but if you "throttle" the lift and curl motions, in other words do not push the handle fully, but kind of modulate it half way, you can get the flow to split the functions and not get the stall you described. As the curl ends you back off that motion on the joystick and continue lifting. Takes a while to master.

paul

 

[seapea]

</font><font color="blue" class="small">( #1 is probably typical on many tractors and is typically lessened once you go just above idle. )</font>

I forgot to mention that the dealer eventually noticed me repeatedly grabbing the housing and eventually reved the engine to make it stop rattling.

 

[DavidVT]

Thanks all,
I will pass on the information/opinions to my friend.
Great forum indeed!
David