[AT] hydraulics question

[Michael P. Maynard]

Cecil, it sounds as if maybe the cups inside your rams are leaking past.. I
have this problem with my TD6, blade only stays up for maybe 30 seconds...
you can see it drop.  I would suggest locating a local Hydraulic repair
shop.  They should be able to get you this parts you need, or be able to
rebuild them for you.  If you want try calling Don or Scott at Cylinder
Services up here in Rochester 585-328-0670  They know their stuff very well,
and should be very helpful to you.  Tell them I gave you their #.

Mike

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Cecil E Monson
Sent: Sunday, January 09, 2005 10:23 PM
To: Antique tractor email discussion group
Subject: [AT] hydraulics question

	I had a problem with the hydraulics on my JD 420 crawler with
a loader. For some reason, I had quite a bit of water in the hydraulic
fluid and apparently ran it that way, unsuspectingly, until I started
to have a problem with the bucket not staying up like it is supposed
to. I used this a lot when cutting firewood by hooking a chain around
a log, raising it up about 3 feet, and then cutting 18" chunks off it
until it was all cut up. Saved a lot of rolling the log to make second
cuts and so on. All of a sudden the bucket wouldn't stay up and that
was when I found the water.

	According to the manual, to test to see if the control valve
is not holding or if the cylinders are leaking past the seals, raise
the bucket and check to see if oil is being returned to the reservoir
if the bucket comes down by itself. If oil is being returned to the
reservoir, it is the control valve. If no oil goes back, the cylinders
are leaking internally. As oil was coming back during the test, I took
the control valve to a shop in New Jersey and had it tested. They said
it was no good and suggested a new one for $650. Instead, I ordered one
from Northern Hydraulics and installed it. Only problem is the bucket
still comes down - slowly but it doesn't stay up. I haven't tested it
again but suspect the control valve again. I don't see any load checks
on it and thought they should be externally mounted. The literature
says only one port has load checks but it does not hold when the lever
is in the neutral position.

	Does anyone know why a load check would not hold in the neutral
position and what good would it be anyhow if it only worked when being
used to lift or lower?

	Being as there are separate forward and return lines, could I
just install external load checks?

	I noticed when looking at the parts list for the loader, that
the cylinders have internal leather cups in them. I suppose this dates
the loader so far back the leather cups are now made of unobtainium.
Or are they still available somewhere?

	Shouldn't a new control valve with center neutral on the levers
hold a load on the cylinders without sagging?  Maybe all my cylinders
have blown gaskets and are leaking. Do you think this could happen to
all of them at once from the water? There are four fairly large cylinders
on this loader - two for the lift and two for the bucket.

	Any comments from anyone who works on his own hydraulics would
be appreciated.

Cecil
-- 
The nicest thing about telling the truth is you never have to wonder
what you said.

Cecil E Monson
Lucille Hand-Monson
Mountainville, New York   Just a little east of the North Pole

Allis Chalmers tractors and equipment

Free advice

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