[AT] I need help on 3 pt

[Larry D. Goss]

The relief valve is usually part of the same casting as the control
valve, Clint.  The diagram I have on my Kubota shows it that way also.
Typically, auxiliary equipment, such as a loader, are either operated in
series with the 3-point, or there is a petcock arrangement on the
control block to switch fluid pressure to one or the other of your
attachments.  On my Kubota, the diverter valve is on the lift cylinder
right behind the driver's knees.  In addition, there probably is an
auxiliary power block located along the side of the engine in the high
pressure line coming from the pump.

The Kubota workshop manual lists these possible problems in the
troubleshooting area:

Unable to lift -- Insufficient oil, Clogged oil filter, Obstructed
hydraulic pipe, excessive load, Improper adjustment of relief valve,
defective gear pump, improper position of directional valve, defective
control valve, broken O-ring at hydraulic piston or cylinder cap.

Slow to lift -- Low oil temperature, loose inlet pipe connection (allows
air to enter), clogged oil filter, insufficient oil, defective gear
pump, scratched relief valve.

There are strainers on the outlets of the oil reservoir.  Those are
separate from the hydraulic oil filter, and those may be clogged.  I'm
not sure how those are removed on your tractor, but usually they are
screwed in from the outside.

USUALLY, there is some sort of cap over the adjustment for the pressure
relief valve.  On some systems though, it's out in the open and
unprotected.  Regardless, it's tempting to tweak that screw and
completely mess up the working pressure of your hydraulic system.

You don't have any dents in the steel lines going to and from your pump
do you?  That sort of thing can cause the symptoms you have.

Larry

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Clint D
Sent: Sunday, March 27, 2005 8:54 PM
To: Antique tractor email discussion group
Subject: Re: [AT] I need help on 3 pt

Larry

Thanks for your reply, I went this evening, pulled the pump and checked
everything
from the pump back to the loader bucket control valve and really did not
find
anything unusual or suspect.

QUESTION,  I have not checked anything from the filter back to the rear
end where
the 3 pt control is, is there supposed to be any relief valves back
there? I have
not seen any evidence of any so far?
I have never done any work around a 3 pt valve, so this is new to me.

What type of areas should a relief valve be for me to check out besides
at the
control valve?

this thing has me totally stumped.

Another question, normally on a tractor like this, is there anything
inside the
trans. compartments in front of the final drive/rear end that could
effect this? I
cannot think of anything myself, but just pulling things from  thin air
right now
trying to get this figured out

Clint


----- Original Message -----
From: "Larry D. Goss" <rlgoss at evansville.net>
To: "'Antique tractor email discussion group'"
<at at lists.antique-tractor.com>
Sent: Sunday, March 27, 2005 6:59 PM
Subject: RE: [AT] I need help on 3 pt


> I would suspect a dirty pressure relief valve, Clint.
>
> Larry
>
> -----Original Message-----
> From: at-bounces at lists.antique-tractor.com
> [mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Clint D
> Sent: Sunday, March 27, 2005 3:39 PM
> To: Antique tractor email discussion group
> Subject: [AT] I need help on 3 pt
>
> Well, I went out and tried to bleed the hydraulic system. I run thru
25
> gallons of
> hyd fluid. I get some pressure from a hose coming from an aux  hyd
lever
> control.
> but with the engine at full throttle I can still hold my finger over
the
> end of
> the line and stop the flow??? A lot less pressure than comes from a
> water hose!
>
> I did have the pump off and all the lines off but see no reason why
the
> hyd pump
> would go from working to being worn out just from R & R it. I checked
> all the
> lines and cannot find anyplace it could be sucking air.
>
> it is weird, I can get fluid to coming out a line and as it starts it
> seems to
> start at a dribble then finally gets a stream going, but like I said,
I
> can put my
> finger over the stream and easily stop the flow, then If I let it sit
a
> few
> minutes, and then try again, no pressure at all, and it will take a
> moment to get
> any pressure at all again,
>
> could a worn pump act like this? once all the pressure is relieved
from
> pulling it
> off, it just looses all its effect?
>
> Clint
>
>
>
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