Regarding 3rd function valve sticking

[J_J]

Maybe this explanation can help some.

CD Industrial Group Hydraulic Solenoid Valve Failure.

Measure the coil resistance with no power, both coils, and let the hyd warm up and then read them again and see if there is any difference. If the resistance changes due to heat, then the coil might not provide enough power to operate it.

 

[slowzuki]

No the coil is operating fine, its a spring return to neutral on these valves. The valve is sticking in an operating position not neutral.

Maybe this e explanation can help some.

CD Industrial Group Hydraulic Solenoid Valve Failure.

Measure the coil resistance with no power, both coils, and let the hyd warm up and then read them again and see if there is any difference. If the resistance changes due to heat, then the coil might not provide enough power to operate it.

 

[J_J]

If it has a mechanical device, as in push here to move plunger/spool at the top of the solenoid, and see if it will release.

There was also a article about contaminated hyd fluid building up around the plunger and spools, causing problems. You might try taking it apart and cleaning the spools and solenoid plunger.

The plunger in my gas solenoid valve for my Kohler carb get clogged up, and I have to remove it and clean occasionally. I have a gas filter in the fuel supply.

 

[nybirdman]

North-east Kubota Rep.
Give him a call...didn;'t resolve the issue but a least rattle his chain so they know "I" am not the only one with this problem.
Jim Carroll 614-835-1100 ex.3900

 

[Rockgod]

I don't know how far you're willing to take this, Kubota know they have an issue...

The more they hear about this problem the better IMO.

http://www.tractorbynet.com/forums/kubota-owning-operating/212805-grandl-buyback.html

 

[brocas]

Just considering different solutions (it will be a long time before kubota admits there is an issue let alone fix it).

From my experience the valve "unsticks" when you press the button for the opposite direction. This makes sense, the spool is suck because only the spring is forcing it to center and I guess the friction is enough to overcome the spring force. But if the opposite solenoid is energized, the spool is forced to move with more force than just the spring.

A simple electronic circuit can be designed that would apply a momentary current pulse of sufficient duration to knock the spool to center position. This current "pulse" would be applied everytime either button is released, if the clamp button is relaesed, the pulse is applied to the opposite solenoid and vice versa.

This would be easy to design and build if I only had a couple of days of free time :licking:.

 

[brocas]

Another potential solution would be to replace the solenoid valve. But what kind of solenoid? I've never seen or heard of an OC solenoid with PB, has anyone?

I must admit I have not even inspected the kubota valve, migh even use a standard base. I'm going to take a look at it this weekend and see...

 

[J_J]

brocas,

What is the brand name of the solenoid valve and model number?

I don't believe the term PB, is associated with solenoid valves or sub plates.

I am not sure how a solenoid valve will work against back pressure. However if you operate the 3pt, the hyd circuit, valves and hoses, are now under pressure for the time the 3pt valve is operated. The pressure could be as high as 2500 psi.

 

[brocas]

Finaly had a chance to look at the solenoid valve. It is made by NACHI. Spec is here:
http://nachihydraulics.com/pdf/Nachi_SK-G01.pdf

It is a tadem type, interestingly the pressure rating on the T port is >3000 PSI.

I'm still trying to figure out if the base is standard. The spec has dimentional drawings. Anybody familiar with standart base dimensions that can confirm this solenoid mounts to a standard base?

I guess the thing to do is to look at another brand of valve known to fit standard base and compare the dimensions. I'm working on this.

I'm hoping I can simply buy another brand of solenoid valve with similar spects and just swap it and see.

 

[brocas]

Looks like the NACHI valve does indeed mount to a standard plate (size D03). Take a look here:
http://www.northmanfp.com/pdf/Subplate02.pdf

Looks like everything matches right down to the mounting bolts :laughing:.