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General Forestry => Forestry and Logging => Topic started by: leeroyjd on March 12, 2013, 04:50:18 PM

Title: swing slow on Valmet 646 in one direction(left)
Post by: leeroyjd on March 12, 2013, 04:50:18 PM
I've changed primary shuttle valve but that was not it.Switched top and bottom lines on section and that just made the right side slow.Not sure what I was hoping to accomplish there.
It responds right away when joystick moved to the right,but hesitates for a second when moved to the left.
Title: Re: swing slow on Valmet 646 in one direction(left)
Post by: snowstorm on March 12, 2013, 05:33:44 PM
pack the steering cyls
Title: Re: swing slow on Valmet 646 in one direction(left)
Post by: snowstorm on March 12, 2013, 05:40:14 PM
only half read it. you mean the crane? there are 4 swing cyl if the packing was leaking in just one of them it could cause it. did you replace the shuttle vavle with a new one? i never had much luck with just replacing the o rings and back up washers
Title: Re: swing slow on Valmet 646 in one direction(left)
Post by: 1270d on March 12, 2013, 06:05:44 PM
Does this have pilot hyd controls or electric controls?
Title: Re: swing slow on Valmet 646 in one direction(left)
Post by: leeroyjd on March 12, 2013, 06:38:50 PM
Snowstorm-yes new shuttle but they do not come w o rings on them,they are separate which I don t care for.If one of the slew cylinders was leaking would I end up w hyd oil in slew bath?
1270D- these are pilot controlled
Title: Re: swing slow on Valmet 646 in one direction(left)
Post by: snowstorm on March 12, 2013, 07:46:57 PM
it could leak internal. past the packing on the gland but not past the rod packing. i havnt bought any shuttle valves in a while. they were around $65 and just the o rings were 20 or so. they also wear in the wobble joint. i have tried setting the new o ring in the sun getting it warm to get it on then putting it on ice hopping it would contract enough to go back in the hole. still didnt work well. these arent your common o rings. i would pull that shuttle out an look it over. the 2 orings are not the same part # so they have to be in the right spot. did it slid in easy or did you have to push it in? 
Title: Re: swing slow on Valmet 646 in one direction(left)
Post by: bushmechanic on March 12, 2013, 08:43:47 PM
Sounds like a pilot system or valve problem but don't rule out a collapsed line or a rubber hydraulic hose that the rubber is letting go on the inside.
Title: Re: swing slow on Valmet 646 in one direction(left)
Post by: miketclew on March 15, 2013, 02:28:17 PM

If you haven't at least replaced the o-rings on the secondary shuttle, I would do that before I did anything else. Watch out for the little ball bearing. I have an old 546 and solved about 6 major problems by re o-ring/washer-ing these primary and secondary shuttles. Some of the o-ring kits I got were so tight I was concerned about cutting the rings when I re-installed the shuttles. There is a chance you damaged an o-ring during re-installation too. Good luck.
Title: Re: swing slow on Valmet 646 in one direction(left)
Post by: snowstorm on March 15, 2013, 08:38:04 PM
miketclew what part of the state are you in?
Title: Re: swing slow on Valmet 646 in one direction(left)
Post by: leeroyjd on March 16, 2013, 05:48:52 AM
I do have a new secondary around here but I thought that if the secondary's were bad both sides of a function would be effected?
Primary made no difference.
Left joystick gets warmer than right,emits noises and vibrations.
Some have asked if I could have air in system,is this possible? It's got a breather or is that just for the tank?
Title: Re: swing slow on Valmet 646 in one direction(left)
Post by: snowstorm on March 16, 2013, 07:52:36 AM
they are tank vents. on my harvester the right joystick gets warmer than the left. on my 646 the joysticks only get hot on a hot summer day
Title: Re: swing slow on Valmet 646 in one direction(left)
Post by: 1270d on March 16, 2013, 09:14:44 AM
Is it possible that a piece of debris got into the valve section and is impeding the main spool?
Title: Re: swing slow on Valmet 646 in one direction(left)
Post by: snowstorm on March 16, 2013, 10:18:34 AM
i have seen something get in the cirert relief  when that happens it may not lift like it should or the cyl leak down