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Dear John, 440a steering/ blade / hydraulics

Started by mudfarmer, March 06, 2024, 06:41:57 PM

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mudfarmer

Well I have dredged through the forum and found some bits and pieces of info but hoping for a smoking gun.

440A, lost steering, blade and brakes very suddenly. It was dark and the fluid seemed low so I walked out and got a pail, put in maybe a gallon. Started up and had all hydraulic functions until I made it to the bottom of the hill, then almost couldn't steer but managed to force it and get out.

Now it is on the landing, the fluid is over full. It will just barely steer a little bit each direction when sitting still, wheel gets impossible to turn, intermittent but difficult steering when moving. Blade will go up and even lift front of skidder but very very glacially slow movement.

The brake pedal is hard all the time and seems to work when moving BUT if I am holding brake pedal and move the steering wheel at all, the brake goes to the floor. Is this pointing at priority valve issue? I was thinking charge pump until I found this last bit of info 

Thanks in advance for any help 

Log-it-up

I had a B model for a while every one I talked to said the a/b model where one of the toughest hydraulic system to troubleshoot i personally am no help but the fellers at J and K equipment in levent Maine are really good with those and have a lot of parts 

Southside

I would say it's the priority valve.  When mine was going you had to be really careful as the steering wheel would turn on it's own back and forth really, really, quickly at times.  Then it would get hard to steer, brakes not work, etc.  I gutted my valve by removing the shuttle and spring but leaving the body there and all the issues went away.  

Of course if I had to turn at the bottom of a hill while braking and trying to lift the blade I suppose something would not work as planned, but the risk of that vs getting my arm ripped off by a self turning, violent, steering wheel was worth it to me.  
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teakwood

I had a problem once with steering and put a new priority valve in and everything was good again. But you problem seems more difficult, definitively attack the priority valve first. 
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mudfarmer

Thanks guys, thought so but always good to get opinion from the brain trust. I will gut the valve tonight or tomorrow night and see what happens. Glad that it waited until end of season to act up. I had been using the blade a ton and steering full lock for a couple of hours putting in water bars. The poor thing is tired, a few hiccups now and then are to be expected ffcheesy

mudfarmer

Gutted priority valve and it is worse, no steering brakes or blade, well blade for first 3sec after starting. I will try to bleed it since that is easy, well already did but after reading book did it wrong  ffsmiley after that will check main pump pressure and that there is least some flow from trans pump, it is only specced at like 4gpm and I don't have a $3k flow meter but do have a bucket.

There were some serious "old heads" that really knew these things in and out like snowstorm, grassfed and others that maybe don't post anymore but you can tell from working on the machine and reading their old posts if there was a bolt they turned it. Thanks to them for sharing the knowledge and to Jeff for giving them a place to share it 👍👍

Brian_Rhoad


mudfarmer

Hi @Brian_Rhoad I cannot see anything in your post or in your gallery but do have the books if you can point me at the section you are referring to. Thanks!

Kodiakmac

Mudfarmer, I had a similar problem with my 440 and with all of the symptoms described by Southside.  I finally tracked it down to a small leak in the steel line fitting on the top of the steering valve housing.  The leak was barely discernable when the skidder was sitting there idling.  I replaced the entire steel line and fittings with a pressurized flex line and presto, problem solved.
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Remle

Have you checked the oil filter in the transmission housing ? If that filter is plugged it will manifest the problems you are experiencing ..

Brian_Rhoad

I tried to upload the pages from the service manual but they disappeared. If you have the service manual, it is section 70 group 5 pages 11 & 12. That gives you the trouble shooting and specs for the hydraulic system.

mudfarmer

Thanks Brian, I have read that section BUT to your point and Remle's, maybe have been straying a bit too much. I know it says right in there somewhere not to bother testing without starting with a fresh filter and I have not in fact started at that point smiley_thumbsdown  Washout here today and 8" of snow incoming, probably won't get to it until Tuesday but thankfully don't need the skidder right now

Log-it-up

I'm not sure but do those have a pick up screen in the trans mission I can't remember I know my C model did not but it was a cross up between the a/b and d models 

mudfarmer

Yes there is a pickup screen in transmission before the charge pump, I will pull and check/clean this as well 👍

mudfarmer

Transmission filter looks brand new, it should at only about 100hrs. Suction screen had a little crud at the back but mostly clean, was a lot worse when I replaced it at the same time as the filter.

Better to check than not! It took me a long time to get a filter, should have just ordered online because it is hard to make the 1.5hr round trip during my work hours but have a few in stock now. Time to refill and then can proceed with checks "by the book"  :thumbsup:

Oliver05262

   Look at your main hydraulic pump to see if there is a stem sticking up from the valve plate. It's maybe 5/16 in diameter with a roll pin through it like a tee handle. That is the manual stroke control.
   If the pump is starting to fail, and generating metal inside, it will cause the stroke control valve in the valve plate to stick and keep the radial piston pump from going into stroke and moving any oil. That's how the system works: when the pressure reaches the set point, maybe 2200 +/- or a little more, the stroke control valve allows pressure oil into the center of the pump and prevents the eight pistons from touching the cam. If the pump is failing—-often the needle bearings under the cam ring are starting to spall— the metal particles will cause that spool to stick.
   If you have the manual stroke control kit on your pump, you can run that stem down until it contacts the valve inside, then turn it down a little more to free up the spool. Then when you run the stem back up the pump should go into stroke. 
   Do the oil and filter change first and don't forget the suction strainer. Brakes that are worn  out can cause the strainer to be plugged. Power shift friction discs can too, but then you would have other symptoms.
   The manual stroke control kit is an option and it might not be installed on your machine, but it is available through parts. Call my cell if I can help. Eight O two 5588161
   
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mudfarmer

Thanks Oliver, no stroke control on this one, looks like pump was replaced relatively recently.

After the filter changes it still had no steering but the blade sort of worked again, a little anyway. Bled the steering valve about 50 times and got steering back but only when moving. Part way through the blade started working :huh?

Even after cutting the filter open it did not look like there was anything actually in it, but I don't think I had it put back together right after the last filter change. The "cone thing" was not in the right spot when it came apart :huh? Weird that it worked for so long if that was the case but oh well onwards and upwards. Thanks as always for the help and suggestions everybody.

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