Kubota M59

[dsgsr]

Having trouble with the Thumb relief valve. Took it to a Hydraulic shop, they took it a part and a plunger pin has a chip in the washer part that allows the spring too pass over the washer after time. The part is probably a 50 cent part and Kubota wants $145. for the relief valve.

Any way of just getting he part? I could order a relief valve from Surplus supply if I new what to order.

Hopefully JJ will reply.


David

 

[J_J]

If it is just an o-ring they should be able to fix it.

If you can't get parts for the valve relief, install a no relief valve in it's place and get an external relief valve.

You would install the external relief just after the pump and before any valve.

 

[dsgsr]

JJ, thanks for the reply. This is a valve for the thumb on a backhoe, it has to have a relief less than the bucket curl. We took the relief valve apart at the hydro. shop. It's not a o-ring, it is a plunger type pin that is pressed back onto a spring (spring looks like the spring in a click type writing pen) too open the valve for relief. This pin has a washer made on it, the washer has a chip missing and that allows the spring to fall over the washer holding onto the pin. In essence holding the relief open. I take it apart fix the spring and it holds for a few hrs. of use.

Kubota wants $145. for just the relief valve (not the hole valve). I'm hesitant to use Kubota parts, I have found numerous parts on this M59 are inferior. Surplus Center has them for 8 to 15 $$ but I'm unsure of which psi setting to get. All I really need is that pin but can not fine just parts on line.

Thanks again,
David

 

[J_J]

Do have the adjustable relief or shims.

If it is shims, they come in a kit, and you use whatever you need to set the relief setting.

Your manual will tell you the relief settings.

 

[dfkrug]

This is a valve for the thumb on a backhoe, it has to have a relief less than the
bucket curl.

That's a work-port RV, aka shock-RV.

If I understand you, the plunger in the RV has in integral shoulder or washer. I would also be unlikely
to buy a new RV from Kubota.

Since you are willing to take the valve apart, try adding a washer of the correct diameters between the
plunger and the spring. If that increases the relief pressure too much, then cut a bit off the end of
the spring.

Pls post a photo of the defective plunger and spring. I am wondering if you have poppet-style or
spool-style RV.

(BTW, Kioti wants over $500 for one of my tractor's RVs.)

 

[dsgsr]

That's a work-port RV, aka shock-RV.

If I understand you, the plunger in the RV has in integral shoulder or washer. I would also be unlikely
to buy a new RV from Kubota.

Since you are willing to take the valve apart, try adding a washer of the correct diameters between the
plunger and the spring. If that increases the relief pressure too much, then cut a bit off the end of
the spring.

Pls post a photo of the defective plunger and spring. I am wondering if you have poppet-style or
spool-style RV.

(BTW, Kioti wants over $500 for one of my tractor's RVs.)

I had considered the washer but was unsure how it would change the pressure. With no way to test it, I did not want too find out the hard way with a bent cylinder. I'll try too remember to take a pic. next time I have it off the tractor. Can't use the hoe right now. Have a broken pin that holds one of the outriggers on, it bent the ears in a little. Will have to straighten them when the new pin gets here. This thing is Nickel and Diming me. On my second BH bucket, first was replaced under warranty because of cutting edge breaking. This bucket has broken on the front corners and I have welded them back (no longer under warranty, but only a couple hundred hours on the bucket) Not impressed.


David

 

[dfkrug]

I had considered the washer but was unsure how it would change the pressure.

Sorry to hear the M59 has not held up in some areas. That is an industrial machine, and Kubota does make
good stuff.

To test the work-port RV, you will have to tee in a gauge at the base end of the thumb cyl. You may not
have the fittings for that, but they are not expensive. When it is installed in a place you can see it,
curl the bkt against the thumb with the thumb extended until the thumb is pushed back. I suspect
your M59 has a system relief of 3000psi or so; the thumb work-port RV is prob substantially lower,
but set conservatively.