Hymac 580 C Cross-Line Relief Valve Adjustment

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Re: Hymac 580 C Cross-Line Relief Valve Adjustment

Post #11 by FOWLER MAN » Thu Jan 24, 2019 11:37 am

strontium90 wrote:Thanks Fred for clarifying that....I will be working with the machine towards the weekend doing some digging and will swap these afterwards...
Yes...there is a Tee on the flexible pipe which feeds into VB3...
I will try to do it on a concrete surface so as if I drop something (which always happens) it won't be lost...I will try to swap the check valves on the CLRV too...will let you know.


Alex

Hi,
Don't swap the check valves in the CLRV and don't mix and match as each plunger should remain with its own seat.
If you need to. Visually check for damage, wear, or bits of foreign matter which may be lodged in them. Check each individualy and return everything to its original location.

Fred


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Re: Hymac 580 C Cross-Line Relief Valve Adjustment

Post #12 by strontium90 » Thu Jan 24, 2019 12:15 pm

Thanks Fred....Understood....I won't touch the CLRV for now as I don't have a pressure gauge to reset it...I'm hoping the check valves between the two feeds to the slew are the culprit..

Alex


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Re: Hymac 580 C Cross-Line Relief Valve Adjustment

Post #13 by strontium90 » Fri Jan 25, 2019 6:34 pm

Ok...removed the check valves and found one had came apart inside...there is a small cross of metal that holds the spring which holds a ball bearing and the spring and cross (Y shaped) are held in with a circlip..
I got another one from our local breaker but I noticed it was installed the opposite way round than the one I removed....i.e. with the spring end facing into the feed for the slew so that the pressure closes it....
I put the pipes together with the ball end feeding into the slew pipes and the machine was very very loose on the slew with no braking..
I then swapped them round (with the spring end into the slew pipe) and the slew function is perfect...
However, I am worried that they both should have the ball end facing into the slew feeds as they are now closed under pressure...I won't operate her until I know for sure..
The arrows that are supposed to be on the valves are illegible...
I need your help Fred...lol
Here is the innards of the check that was broken
Check.jpg

Here are the valves at the breakers
Scrap.jpg


I must say that the workshop manual is useless as there is no information on installing these crossline valves between the feeds and there seems to be two different types of cross line relief valve...one with two individual valves for each feed, like in the picture from the breakers and my type with a single adjuster underneath...photographed in a previous post..
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Re: Hymac 580 C Cross-Line Relief Valve Adjustment

Post #14 by FOWLER MAN » Sat Jan 26, 2019 12:05 pm

Hi,
That's fine, good to have been of help :thumbup: .
I have never been aware of direction arrows on these check valves but it's easy enough to see how they work. :think:
As you say Hymac manuals were never the best. Hymac had a policy of constant development and improvement and the manuals never kept pace with the changes. :?
It's the 1980s since I worked on these, so without your pictures to jog my memory I would have been lost.
Good luck.
Fred


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Re: Hymac 580 C Cross-Line Relief Valve Adjustment

Post #15 by strontium90 » Sat Jan 26, 2019 1:19 pm

Thanks a lot Fred...I have tested her this morning although on level ground and the slew function is much improved....she stops where I want her to which makes digging a lot easier :D

I have left the check valves to close when the slew is operating so I'm reasonably sure that is how they should be....the "creeping" to the right is much less, but it could be :-

1) The check Valve in the CLRV
2) A fault in the spool valve control
3) Seals in the Staffa motor

I am going do a bit of digging on Monday so will see how it is then..
It is great to speak with someone who knows these old beasts....you are a tremendous help..

Alex


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