[AT] hydraulics problem

Fri Feb 10 07:07:01 PST 2006

Lew:

	I have a '58 420W with a very similar power steering setup.  It appears
from the picture that you must have the earlier flow-divider setup, rather
than a separate pump.  From my experience, there is little to go wrong with
the valve, and there is also little to fear about disassembling it.  If I
remember correctly (it was 5-6 years ago), all of the rubber parts are
standard o-rings that can be had at any hydraulics supply house.  The only
tricky part is getting the detent balls and their springs back in, and I
don't remember having trouble with that.  The JD manual is pretty good about
pointing out the pitfalls and the way around them.  If your woodruff key
seat(s) is (are) in bad shape, you may be able to have another one re-cut
180* from the original.  Keep in mind that this will weaken the shaft, and
may cause a wreck!
	The biggest trouble I had with this system was in reducing the backlash to
an acceptable level.  IMHO there are too many opportunities for lost motion.
The three steering shaft couplings (and u-joint if you have a '58 or later
model), steering gear, and steering gear output coupling are all places
where play develops, and should be eliminated for best system operation. The
Ross steering gear is a good place to start.  If your worm is not worn
excessively, the tapered studs that ride on it can be replaced for a big
improvement. JD still had those available last I knew.  New studs will make
it much easier to adjust the box so it is free turning, but with minimal
backlash.
	I let a NOS worm get by me the other week on Ebay, and that would have
helped my tractor a lot, since I still have some play in my steering box
that I couldn't eliminate with the pin replacement.  Every once in a while,
you will see some valve parts on Ebay as well, so don't lose hope entirely.

Sorry this got long,

Brett Phillips
back to lurking

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com]On Behalf Of Lew Best
Sent: Friday, February 10, 2006 1:02 AM
To: 'Antique tractor email discussion group'
Subject: RE: [AT] hydraulics problem

Thanks Cecil

Guess I wasn't clear enough; this is a rotary valve in the steering
shaft.  When putting pressure on the wheel to say the right it sends
pressure to the cylinder to "help" push the wheels one way.  Once you
release the steering wheel (or stop because you've reached the point you
want to turn it to) the valve drops back to neutral.  For a pic you can
go to http://img.photobucket.com/albums/v707/lewbest/steervalve01.jpg.
The top & bottom hoses go to the cylinder; right goes to pump pressure &
left to pump suction.  The gearbox on the steering still functions;
hydraulic power just "helps" move the steering knuckles.

Lew

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Cecil Bearden
Sent: Thursday, February 09, 2006 10:51 PM
To: Antique tractor email discussion group
Subject: Re: [AT] hydraulics problem

Lew
you mentioned that the roll pins had been replaced.    Check to see that
the
control valve can move in and out.  My old Massey had a slot that the
roll
pin in the control valve shaft slid in and out to regulate the fluid.  I

reamed it out to pin it solid. and had no more Power steering...

Cecil in OK
----- Original Message -----
From: "Lew Best" <bee_keeper at earthlink.net>
To: <at at lists.antique-tractor.com>
Sent: Thursday, February 09, 2006 6:25 PM
Subject: [AT] hydraulics problem

>
> Hey guys
>
> Got a problem; (so what else is new)?
>
> On an old John Deere 420 power steering it's doing something crazy!
> Solved a few problems yesterday; got it to turning pretty good one way
> but not near as good the other.  Had a bad leak on one of the rotten
old
> hoses coming from the control valve to the cylinder so replaced the
hose
> today thinking that would fix it.  Well, that made things worse!
Seems
> that when it had pressure on the good hose that the leak let the
return
> fluid from the cylinder out so it worked.  Now (with no leak for the
> return flow) no turn either way.  Someone had obviously had problems
> with this steering before (had sheared keys & roll pins, etc.) so now
> I'm kinda grasping at straws.  What is obviously supposed to happen is
> when you turn there should be pressure to one end of the cylinder
making
> it push & the fluid from the other end be allowed to go back to the
> suction side of the pump.  Is there a check valve inside of the
control
> that could be stuck? I've removed the hoses one at a time (right, left
&
> return) & all seem to squirt fluid "when they should."
>
> BTW I wanted to replace one of the shafts in the valve (pretty well
> mutilated) but the shaft is no longer available thru JD.  Asked about
a
> complete valve & same response.  Hate to tear into it not knowing if
any
> parts available (seals, etc.) but guess I'll have too.  No good the
way
> it is!  Anyone got one (or know of a source) without having to give an
> arm & a leg for it?
>
> Any ideas appreciated!!!!!!!
>
> Lew
>
>
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> Remembering Our Friend Cecil Monson 11-4-2005
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