Turning up the hydraulics

[1TMatthews]

I have a B7800 I thought i heard that the factory settings on the Hydraulics are set low. Is there a way to turn them up a bit? If so How easy is it to do ?

Thanks.

 

[ccsial]

There should be a relief valve but I don't know where it is. Before you turn it up you should see if your FEL lifts the rated load. Turning it up too much may damage the FEL if you overload it.

 

[JrsL5030]

I want to turn my up too, so please post if you find out how. thanks

 

[MadDog]

Assuming that you find out how to turn up the relief valve, how are you going to know how much you can safely turn it up without overstressing one or more of the componants of the hydraulic system, i.e, cylinders,pump, filter, reservoir, hoses, fittings, etc. or the structures that it operates, such as FEL and 3ph arms?

I sure wouldn't want to tinker with the hydraulic system unless I knew that setting the relief higher wasn't going to impose loads that the tractor isn't designed to handle.

Just my $.02 and I suppose that if I were an engineer, maybe I could figure out the answers.

 

[KubotaTrax]

Sorry I don't have the Answer, But I can tell you this.
I also have a 7800 and investigated the problem all the way to the dealer. I found out that the pressure is controlled by a relief valve that has to be shimmed to increase pressure.
"Sounds easy...I can do that. " The next problem is you have to start at the seat and disassamble the tractor down to the valve which is located INSIDE the HST unit. The dealer said "We can do it in about 2hrs labor and by the way if we touch the valve your warranty goes out the door."
"Hmmmm...Ok, thanks anyway."
That's what I said....I didn't say I'd give up.
If I find the answer...I'll pm you.
Hope this helps.

 

[MadReferee]

By hydraulics do you mean the HST itself or the implement control system?

The implement control system (loader and 3pt) has its own relief valve which should be set in the 1920 to 1991 psi range. It is located on the top of the hydraulic cylinder body (3pt) and requires some disassembly to get at.

Get yourself a workshop manual if you want to play with this setting. Complete instructions on how to disassemble to get at and adjust this valve are there. However, you will need some special tools including a pressure gauge.

Checking to see if the pressure is correct is a relatively simple procedure that your dealer can do rather quickly. I would check to make sure the pressure is within range before doing anything to the system that might void the warranty.

 

[CT_Tree_Guy]

Turning up the hydraulic relief setting should be a very easy thing to do, or have done if you don't have the gauges/fittings. (I didn't). My 853 loader was noticeably weak, and it turned out the relief valve was set below spec. To me, a loader or any other attachment should be able to handle the full pressure that the system is supposed to be at. Adjusting the pressure to higher than the spec pressure is where you could run into trouble, but at least make sure it's up to it's maximum setting. And I can't imagine it involving major surgery, or voiding the warranty - you're just setting the pressure to its spec.

Here's part of the exchange I had with someone about this:

He posted:

"The hydraulics seem weak on the FEL. They go into bypass rather quickly and I am wondering if this is normal. Am I expecting too much?? Are they adjustable? My wife asked the dealer about the issue and he broke into a long one-sided discussion on the bypass mechanism but never answered the question on whether they can tweaked to give us a little more power."

*****

Jxxxx - I think your dealer needs to buy a vowel. I am pretty darn sure that you can get more power out of your loader. I experienced the same exact thing with my 853, and just talked about it when I posted some pics of my 5030 which is set up for tree work. I believe the max psi is 2,560, and mine was set at the factory to more like 2,300. It is a very simple matter to have a (genuine Kubota) shim or two added in the relief valve to increase the setting (my tractor guy did it for me in about 15 minutes), and the added psi seemed to make more of a difference than the raw numbers would seem to indicate. As I said in one of my other posts, it went from "hmm, this loader doesn't seem to have enough ooomph" to "ok, that's more like it".

In fact, unless my calculations are off, and I don't think they are, I am now able to lift over 3,200 lbs, including my 800 lb. grapple. The stated lift capacity for the 853 is 1,874 lbs. at bucket center, so maybe Kubota is just trying to make sure that their tractors don't get worked too hard.

********************

There you go - get those relief valves set at the max, or just under. It really does make a difference.

John D.

 

[MadReferee]

Make sure you understand what is happening here. There are two relief valves in the implement circuit when a loader is installed. The first is the system relief which is located above the hydraulic cylinder (3pt). The other relief valve is contained within the loader's spool valve.

The usual culprit is the loader relief valve which is not set correctly. It should be set close to or just over the system relief.

The system relief setting should not exceed the Kubota specs (1920-1991 psi).

 

[5030]

Besides, if you set your loader relief valve over the specified pressure (almost always found in your manual), you will probably pop a seal on one of the cylinders or the weakest point in the system.

 

[CT_Tree_Guy]

Mad -

Nice to cross paths with you, I've always enjoyed your posts.

Excellent point about the two relief valves, I'm going to have to look into this some more to determine exactly which one we adjusted, or both. From looking at my manual, and because of a recollection that I got some additional lift from the 3PH as well as the loader after the adjustment , I think it was actually the main relief valve that was set low.
John D.