853 main control valve

[perry]

The left foot paddle has a couple of hard spots, when I try to let the arms down slowly it hangs up at the hard spot and jumps to fast down?. If I put hard foot pressure on the paddle I can control it. Not something I want to do when working.
The previous owner said he had the main hyd. control valve rebuilt?. Any suggestions?.

Thanks

 

[perry]

Just curious if the lift and tilt spools are known to stick?. From the parts catalog it seems they can be removed without pulling the main control?.

Thanks

 

[thetool]

It's either linkage or the spool. My guess is the spool given recent "rebuild".
Lift your cab, disconnect the linkage and check for the hangup. This isolates the spool or linkage. If it's the linkage, it's easy to find the problem with it disconnected from the spool.
If it's in the spool, it can be a piece of debris, probably a piece of O-ring from soemwhere(metal debris will cause a more severe jam-up) but my best guess is your detent cap has been improperly assembled, a common occurrence during valve rebuilds.
There are little balls and springs for float detents and if they're jangling around out of place it will give you such troubles.
The lift spool is the middle spool on your valve, with the long back-cap. You need to drain your hydraulic tank-clean catch if you want to re-use, and if you're lucky, you can slide the spool with the cap to the rear of the valve and out after removing the socket-head capscrews, fore and aft along with the boot, with a 3/16" allen.
Don't pull the cap off the spool or springs and balls go flying. There's an e-clip holding the cap to the guts inside. Remove the clip and slide the cap off. The guts are held to the spool by threaded stud. This loads the centering spring and the spring washers should be centered on the assembly. You will also see at this point if your springs and balls are out of place. You need special pliers to assemble it correctly.
My advice is if you want to fix it yourself, pull the spool up to that point and take it to the dealer and watch while the detent section is assembled, then take it back and re-install it, with new spool seals.
Good luck.

 

[perry]

It's either linkage or the spool. My guess is the spool given recent "rebuild".
Lift your cab, disconnect the linkage and check for the hangup. This isolates the spool or linkage. If it's the linkage, it's easy to find the problem with it disconnected from the spool.
If it's in the spool, it can be a piece of debris, probably a piece of O-ring from soemwhere(metal debris will cause a more severe jam-up) but my best guess is your detent cap has been improperly assembled, a common occurrence during valve rebuilds.
There are little balls and springs for float detents and if they're jangling around out of place it will give you such troubles.
The lift spool is the middle spool on your valve, with the long back-cap. You need to drain your hydraulic tank-clean catch if you want to re-use, and if you're lucky, you can slide the spool with the cap to the rear of the valve and out after removing the socket-head capscrews, fore and aft along with the boot, with a 3/16" allen.
Don't pull the cap off the spool or springs and balls go flying. There's an e-clip holding the cap to the guts inside. Remove the clip and slide the cap off. The guts are held to the spool by threaded stud. This loads the centering spring and the spring washers should be centered on the assembly. You will also see at this point if your springs and balls are out of place. You need special pliers to assemble it correctly.
My advice is if you want to fix it yourself, pull the spool up to that point and take it to the dealer and watch while the detent section is assembled, then take it back and re-install it, with new spool seals.
Good luck.

Thanks, very helpfull............

 

[Tazza]

Thanks, very helpfull............

Before you go to that much effort, remove the linkage at the spool, rotate it 180 degrees and try it. May sound silly, but some times this helps. It was in my 731 manual if the spool was tight or sticky in the body, rotate it 180 degrees. Worth a shot isn't it?
I do agree that if it is a bit of rubbish stuck, it will most likley be a bit of O ring.
Good luck!

 

[perry]

Before you go to that much effort, remove the linkage at the spool, rotate it 180 degrees and try it. May sound silly, but some times this helps. It was in my 731 manual if the spool was tight or sticky in the body, rotate it 180 degrees. Worth a shot isn't it?
I do agree that if it is a bit of rubbish stuck, it will most likley be a bit of O ring.
Good luck!

Thanks Tazza, I'll give it a shot.The previous owner said he paid $100 to have the main control rebuilt, sure would be nice to have an extra fresh control to replace immediately.
Does my 853 have the 'lock' float buit into the paddle and main control?. if so it dosen't work, I must hold it down to make the float work?.

 

[thetool]

Thanks Tazza, I'll give it a shot.The previous owner said he paid $100 to have the main control rebuilt, sure would be nice to have an extra fresh control to replace immediately.
Does my 853 have the 'lock' float buit into the paddle and main control?. if so it dosen't work, I must hold it down to make the float work?.

When you push your left pedal all the way forward, it is supposed to click into float. This pushes the lift spool all the way back, past the boom down position, and the spool locks into a detent mechanism in the spool cap on the back of the valve.
This is where the springs and balls I was referring to earlier come into play. They are in the back cap, and it's called the float detent section.
If it's not working, and you have that catch in your pedal travel, the problem's most likely in that cap.

 

[perry]

When you push your left pedal all the way forward, it is supposed to click into float. This pushes the lift spool all the way back, past the boom down position, and the spool locks into a detent mechanism in the spool cap on the back of the valve.
This is where the springs and balls I was referring to earlier come into play. They are in the back cap, and it's called the float detent section.
If it's not working, and you have that catch in your pedal travel, the problem's most likely in that cap.

Might as well pull it and fix it, really aggravating when working.

Thanks for the assistance fella's..........