3-Point Hitch kubota b7100 3 point linkage will not lower when engine is running

[grandee]

I have a B7100 4wd and 3 point linkage will not lower whilst engine running but lowers very slowly when engine not running.
Lifts ok as always and oil levels all check out ok. 4wheel drive ok high/low ok.pto works ok.
Nothing ever been attached to hydraulics other than 3 point linkage for small plough and a subsoiler and the pto drive for a rotovator.
The tractor has always worked very well in the past but has just developed this fault. Can anybody help please??
Tractor serial no. 752387

 

[skyhook]

Is there a little knob in front of the seat, if so, this will adjust the lowering speed of the three point, turn it counter clockwise to increase the decent speed.
Someone may have closed it.

 

[s219]

Yeah, I suspect the knob is turned all the way to close off the descent.

 

[davesl708]

Welcome to TBN.

Since the 3ph goes down when the engine is off but not when the engine is running suggest the lift control valve may be leaking by and keeping pressure on the lift. If the lowering control valve is not the issue you may want to check the lift.

 

[grandee]

Hi the operator manual says the knob under the seat with Yellow arrow on is for opening and closing valve to operate attachments?
Have previously turned this half a turn(it is very stiff)but not turned with ref. to this problem??? Will try again. cheers

 

[grandee]

As per previous suggestion - Does this knob turn on/off on off or does it unscrew outwards? the manual refers to arrow on knob as pointing in one particular direction to open and close hydraulics to attachments.

 

[grandee]

Hi dave
The 3 point lifts ok. but it will not lower at all when engine is running?? If I stop the engine and try to lower it will lower very slightly and reach the bottom taking about 15-20 minutes, and thats with a plough attachment loaded to the hitch. Where and what is the valve location is it on the lever?
Can I disassemble or is that not possible

 

[bumperm]

The knob's purpose in life is to modulate or regulate the rate with which the 3 point hitch lowers. Screwing it in (clockwise looking at the knob) all the way will lock the 3 point hitch from lowering, but not from raising. Unscrewing the knob will increase the lowering rate while screwing it in slows the rate. Of course the rate is also affected by the implement weight, so the knob will typically be adjusted to suit both implement weight and desired results.

 

[Egon]

The Kubota b7100 HST I had did not have such a valve. On mine adjustments were on the control lever slide for stop points. No rate of descent valveing.

 

[davesl708]

Hi dave
The 3 point lifts ok. but it will not lower at all when engine is running?? If I stop the engine and try to lower it will lower very slightly and reach the bottom taking about 15-20 minutes, and thats with a plough attachment loaded to the hitch. Where and what is the valve location is it on the lever?
Can I disassemble or is that not possible

I am referring to the lift lever that raises the 3ph. the valve is inside the trans most likely. It may require a lot of tear down to get to it. That is a last resort.
I would make sure the drop rate control valve is open. It should screw open so you can control the rate of drop.
As Egon has mentioned his b7100 does not have such a valve.