Jcb 527-77

[Bdundridge]

Hi all,
I have today refitted the spool valve assembly after replace spool seals only. Upon testing I have found that when I operate the tilt function one of the two boom lift rams also trys to work, causing the boom to try and move sideways.
Can anyone advise why this might be happening?
Thanks in advance.

 

[Tomtrac]

Hi all,
I have today refitted the spool valve assembly after replace spool seals only. Upon testing I have found that when I operate the tilt function one of the two boom lift rams also trys to work, causing the boom to try and move sideways.
Can anyone advise why this might be happening?
Thanks in advance.

I am only guessing but there could be a ram or two conected to the boom and main frame as boom goes up they extend and are teed into crowd ram to work self leveling
Hapen they are plumed in wrong or something

 

[Bdundridge]

Thanks for your reply, Im at a loss as to why this is happening as I labeled each pipe as I removed them so that they could not be mixed up.
Unsure if I can get some sort of diagram to check hose connections, but can't believe I have mixed them up.

 

[ACEngineering]

Hi all,
I have today refitted the spool valve assembly after replace spool seals only. Upon testing I have found that when I operate the tilt function one of the two boom lift rams also trys to work, causing the boom to try and move sideways.
Can anyone advise why this might be happening?
Thanks in advance.

Pins and bushes are worn.
When you move tilt ram it's also powering up the self level ram so any play in pins and bushes boom will jump around as the self level ram stresses it each way.
Sounds perfectly normal other than worn pins/bushes.

 

[Bdundridge]

Thanks ever so much for your reply AC. This fault was not apparent before I had the valve chest out, so can only be because of something I have done. I have no previous experience of working on these but lots with light vehicles.
So still at a loss!
Can anyone tell me if I can disconnect some of the spool hoses without oil loss as long as that spool is not operated or not?
Thanks.

 

[Tomtrac]

Thanks ever so much for your reply AC. This fault was not apparent before I had the valve chest out, so can only be because of something I have done. I have no previous experience of working on these but lots with light vehicles.
So still at a loss!
Can anyone tell me if I can disconnect some of the spool hoses without oil loss as long as that spool is not operated or not?
Thanks.

Probly not just put everything on ground bucket etc
You could try blanking off the self level ram pipes on side off boom or better still send me a video off what its doing it sounds like two rams are fighting if its tryin to twist the boom
on some models if you put key on to ignition when holding lever it may dump oil but most diggers etc run on what i call a pressure return so even if the pipe hasnt any weight on it it still has a preshure in it
If you can send me a video let me know and i will put up my tel number

 

[Bdundridge]

Thanks very much for your reply.
I am now away from the machine for the next week so will try to capture it on a video when I'm back again.

 

[Bdundridge]

Had a chance to have another look at this machine today, and noticed when raise the boom and return the spool valve to the neutral position. One of the two boom rams can be seen to sink again. The same will happen in reverse if you lower the boom onto something, as if you wanted to raise the front wheels from the ground.
I realize this is only evident because of some wear in various pins etc, but think this has highlighted an issue with system pressures not being maintained (at least in this ram) ?

Just wondered if this might promote any more thoughts from you guys.

Thanks all.

 

[ACEngineering]

Put the forks level and lift and lower it a few times.
If it self levels about right the system is fine and the self level or compensation rams as there called are doing there job. so just replace the worn pins and bushes as required.

 

[ACEngineering]

If the boom is moving side ways its got wear on the main boom pivot pin and bushes!

 

[Bdundridge]

Thanks for your help once again.
The forks are self levelling, so thats good news!
I have also noticed that one of the pair of boom lifting rams has a leak, so loses pressure when control lever is returned to neutral position, and due to wear in various componants is allowed to sink around half an inch or more! The next time the controls are used the ram in question will then kick in first, causing the boom to kick sideways. If there wasn't any wear / play in the componants I'm sure the lazy ram would have much less apparent.
So yes, as you say, I will have to replace the pins etc and additionally replace the ram seals also, which I will now need to work out how to best tackle.
I've opened a can of worms!
Im sure I'll be back looking for help / advice as i attempt to tackle any issues in the future. I have found the forum and your comments to have been a fantastic help.
Will update the forum when the repairs have been completed.
Thanks again.