Need hyd valve diagnosis help B7500

FandJ

New member

Equipment
b7500
Apr 19, 2015
2
0
0
CT
Hi.

I am helping a friend with a B7500 tractor that has had a front loader in perfect working condition.

He just bought a brand new in Kubota crate, front snowblower with hydraulic motored directional chute.

We followed the hyd hose instructions many times, hooking the new blower to the 4 existing loader valve body connections.

The blower lifts and lowers perfectly.

The hydraulic motor to rotate the snow chute only moves the chute in one direction. When trying to go the opposite way, the hoses flex like a blockage.
....And the hoses stay flexed from high pressure when you let go of the joystick


Next, we swapped the two hoses to the chute. It now will go the opposite direction, but now won't go the opposite way that it did before. So, the chute motor is OK

Next, we assumed the "old" male quick disconnect fitting on the "suspect" valve body connection was not letting fluid pass into the new female quick fitting on the new blower hose. So we eliminated both quick fittings by using two swivel unions. The chute still only goes one way.

Next we put an inline pressure gauge at both chute hoses. On the circuit that does work OK, the gauge shows 1500 as you rotate the chute, then quickly drops as you let go of the joystick. On the "bad" side, the gauge goes up to 1500 but stays at full pressure as you let go of the stick.

So we thought plugged return. We pulled that spool out of the valve body, and everything looks clean.

We then swapped all 4 of the hoses to see if the "suspect spool" could raise/lower the blower, and to see if the chute would now go both directions. The chute now works perfectly both directions, but the when you push down on the blower to lift the front tires off the ground, it stays up, and won't let that lift cylinder to retract, so the tractor gets stuck up in the air.

The crazy part: We took the blower off. We put the front loader back on. The bucket raises and lowers perfect, and the curl/rotation of the bucket works perfect.

... BUT..if we swap those 4 hoses, the curl still works perfect, but when you lift the tractor wheels off the ground by lowering the bucket, the front wheels stay off the ground when you try to raise the bucket. ??

We got out the bucket intallation manual to see if the original bucket valve body hoses were hooked to the tractor correctly when the tractor was new. Like the "pressure beyond" and "pressure", and "return", to the transmission side, and to the fluid block. They match the book.


How can the bucket attachment work perfect, but we keep getting symtoms of a blocked return line on other test hookups?
 
Last edited:

ShaunBlake

New member
Lifetime Member

Equipment
B6100D; B219; Piranha bar; Hodge stabilizers; Filled Ag rears; R322T w/48" deck
Dec 21, 2014
899
1
0
81
Sugar Hill -- next door to Buford, GA
Hi, and welcome to the OTT forum.

I am very ignorant of the intricacies of hydraulic systems and have no advice to offer, except to be patient. So far, there have been only about 25 viewers of your post; some of the gurus will eventually come along (prolly typing their well-researched responses as I post this) and offer some good suggestions.

I hope you don't get frustrated -- it seems that you have done a remarkable job of analyzing and troubleshooting this conundrum, and I take it that you have considerable experience, which makes it all the harder to not pull your hair out. I'm glad J has such a great friend in you, and with such experience and intellectual ability!

Best wishes in your endeavor to get that s***blower blowing s***!
 

Kennyd4110

Well-known member
Vendor Member
Sep 7, 2013
1,164
329
83
Westminster, MD
www.boltonhooks.com
Welcome to OTT,
Your problem is a common one, it's called "regen" or the "regenerative" function of the some, AKA "fast dump". Some older kub machine only had 3-way valves and can't operate plows or chute rotator. Hopefully for your friend pushing the joystick harder to the right will work, otherwise a new valve or control is needed.

Here is some more reading, read post #3 and #4: http://www.orangetractortalks.com/forums/showthread.php?t=12444&highlight=regen
 

FandJ

New member

Equipment
b7500
Apr 19, 2015
2
0
0
CT
Welcome to OTT,
Your problem is a common one, it's called "regen" or the "regenerative" function of the some, AKA "fast dump". Some older kub machine only had 3-way valves and can't operate plows or chute rotator. Hopefully for your friend pushing the joystick harder to the right will work, otherwise a new valve or control is needed.

Here is some more reading, read post #3 and #4: http://www.orangetractortalks.com/forums/showthread.php?t=12444&highlight=regen
Kenny, Thank you! ...for taking the time to be on a forum to help others!

I can fully comprehend the problem in the way that you explained the differences in the spools/valve body.

I thought about your post and link, for an hour, and I now prefer to talk the owner into buying the correct 4 way valve body, rather than using an aux valve, without letting cost difference sway the choice.

I hope all the forum members understand how you all are making someones life a little brighter, by donating some of your own time and thoughts...Thank you again!