Catastrophic Failure

[DFB]

This what the internals my rockshaft control valve look like

#18-20 are the relief valve components

 

[DFB]

The attached pics are from the WSM for my tractor, an L3400. It shows the cylinder safety valve being set for roughly 3000 psi (2845-3277 psi), which is well above the normal relief setting of 2250psi, and the hydraulic diagram shows where everything is plumbed in relation to each other. The lowering valve (6) is shown in green, the cylinder (7) is in yellow, as is the safety valve (8).

View attachment 301154View attachment 301155

Sean got any other pictures of the location of that valve or the control asy?

 

[Chilly807]

Item 160 is the safety valve on my L3400 parts view, and in the second pic, it's located in front of and below the seat next to the lowering speed valve. It is possible to move the adjustment externally, not that you would ever want to. You have to have it disassembled to attach to a pressure source to test it. I'm thinking the L2900 is similar in design to the L3400, although it may not be.

Should be possible to get an L2900 parts breakdown online if anyone wants to look.

I suppose it IS possible that someone moved the adjustment in the past thinking they were adjusting something else, maybe trying to increase the hydraulic pressure to the 3pt or the main relief valve? If that's the case, if you screwed it in it would increase the relief pressure all right, but only on the safety valve, not the main hydraulic relief. No increase in performance, but a potential problem waiting to happen.

A question for the OP.. have you had the tractor since new? The previous owner may have tried a few things.



Sean

 

[DFB]

Thanks that puts a lot in perspective :thumbsup:

 

[PitbullMidwest]

... A question for the OP.. have you had the tractor since new? The previous owner may have tried a few things.

View attachment 301201View attachment 301197

Sean

No, I bought it used in February 2008. The previous owner was the owner of the dealership I bought it from

 

[Chilly807]

According to this parts list (can you tell we're housebound with snow?), your tractor does have the safety valve, it should be located just below the lowering speed valve. The picture shown in the parts list looks different from what you have, but that doesn't mean much.

Kubota Tractor Corporation - Parts List



Sean

 

[DFB]

Curious..where is the main relief valve located?

 

[Chilly807]

On mine it's located under the right side floorboard, and sets the maximum pressure for the whole system. I think the loader valve has it's own pressure relief, and my remote valve definitely does. So, if the main relief is set at 2250 psi that's the most you can get at any implement, possibly less if the valve for that implement is set to a lower relief pressure. As an example, my remote valve is set at 2000 psi with the output dead-headed. It came that way and I've had no reason to change it.

Sean

 

[DFB]

Yes I followed your link and looked up the relief valve for that L2900GST It picture shows it is located inline between the pump and block

 

[yelbike]

Any fix yet?