Loader 'curl' is weak

[California]

Loader \'curl\' is weak

I needed to transport some water for some newly planted trees. No problem, I'll just deliver these three unused garbage cans in my loader. About 600 lbs, with the center of gravity beyond the bucket lip.

I had no problem lifting the weight but I discovered the bucket 'curl' slowly droops forward so I had to stop every minute, set it down, and curl it back. I thought 'curl' should be stronger than 'lift'. Pulling the curl lever under load was worse, it drooped as soon as I pulled it back from center position and higher rpm didn't help.

I assume I need to overhaul or replace the loader control. Is this a DIY project? Cost?

The loader is a 20 year old Great Bend GB-20 with two separate control levers. Its lift capacity is considerably more than the 700 lbs I have used it for so far.

Has anybody repaired a similar problem? Advice?

 

[JerryG]

Re: Loader \'curl\' is weak

Sounds like normal bleed by to me. The spool to housing is metal to metal, thus nothing to rebuild. There are a few o-ringsl on the valve, but they are mainly to prevent leaks. Either the tolerance stack is causing it or the spool is worn. But a large amount of bleed off is normal. /forums/images/graemlins/crazy.gif

 

[Jim_Fisher]

Re: Loader \'curl\' is weak

California,

</font><font color="blue" class="small">( Has anybody repaired a similar problem? Advice? )</font>


I had a similar problem on a John Deere 430 loader. Rebuilding the curl cylinders resolved the issue. You need to do a bit of diagnosis before proceeding.

Assuming that the loader boom is not weak and doesn't leak down at an unacceptable rate, change the curl circuit to the boom valve spool and the boom circuit to the curl spool.

If the problem is the valve spool, I would expect it to now move to the boom. If the problem is in the curl cylinders, it should stay with the curl.

Let us know what you find.



Jim Fisher

 

[jmc]

Re: Loader \'curl\' is weak

Sometimes for diagnosis, you can switch hose pairs at the control so that the lift circuit operates the curl, and the curl circuit operates the lift. If the curl is still bad, it is probably the curl cylinder(s) or curl hose restriction. If the problem moves to the lift, its the control.

 

[SPIKER]

Re: Loader \'curl\' is weak

A much easier way to trouble shoot it is at the cylinder where the hose attaches to it at. One hose will be attached at the lower end twards the bucket, this hose is under pressure when the curl back is used, NOW take the other hose end off. at the curl down end, (upper end of the cylinder) make sure you have a bit of weight in the bucket , if there is leakage at the cylinder then fluid will ooze out of the nipple where the hose was disconnected from, if it runs out of the hose (then the other side cylinder is the bad one.) if NO fluid oozes out then it is in the valve which is bad, and probably will have a cut o-ring or worn spool...

be sure to think it through before taking any hoses lose too... the PRESSURE PUSHES aginst the piston / rod and PUSHES the bucket back. to UNCURL it goes the toer way and fluid pushes aginst the piston top and none aginst the rod. this extends the rod and causes the bucket to curl forward into the dump postion...

Mark M... /forums/images/graemlins/smile.gif

 

[California]

Re: Loader \'curl\' is weak

That is great advice, to swap hoses, and also to open a connector to see what leaks under what control positions. I appreciate the input. These diagnostics should pinpoint where the problem is.

I suspect analysis will show that the curl valve is leaking internally. Assuming this is the case, is it simple to pull a detent spring or something equally easy, slide out the piston, and replace o-rings? Or do I need to remove the control and take it to a hydraulic specialist. I assume repair will cost far less than replacing the control outright?

Thanks for any and all advice!

 

[JerryG]

Re: Loader \'curl\' is weak

The spool is metal to metal, no-rings.

 

[jinman]

Re: Loader \'curl\' is weak

Control valves are made to very tight tolerances and are almost never the problem. Don't tear into it until you check your curl cylinders. If your valve isn't sticking open, the cylinder is surely your culprit. /forums/images/graemlins/smirk.gif

 

[SPIKER]

Re: Loader \'curl\' is weak

I have not tore into any spool valves in for ever: some DO have o-rings, some do not, some have teflon back up o-rings with speciallized o-rings that can only be repaired using an OEM kit. not many are made the same way... Same goes for the Hydraulic Cylinders, but typically they have more redily available kits for rebuilding them, I saw them at TSC this past weeek even.

I was a Hydraulic Specilest in Air Force in Hydraulic Back shop for 4 years.. Can't tell you how many Brakes, Accumeulators, Actuators and misc componets I rebuilt!
Same for making Hoses and such! more than I could count...


Anyhow good luck with the leak down prob. My loader does the same thing in both curl and lift. I suspect mine to be more of a relife valve problem, something stuck or a tear/cut in an o-ring. lots of times a small metal flake will come loose and stick in the seat once stuck it will stay there. gets imbedded into the o-ring or even will sice the o-ring a bit. after that it's all over but the rebuilding! /forums/images/graemlins/frown.gif

Mark M

 

[JerryG]

Re: Loader \'curl\' is weak

Spiker,
Jim and myself, have been referring to loader valves only. The loader valves on compact tractors are low end valves. I have no doubt that you have rebuilt valves that have o-rings and backers, but those are much more expensive valves than are on these compact tractors.