FEL grapple 'close' is weak...help please

Patk · Jun 26, 2004

FEL grapple \'close\' is weak...help please

My new Kubota L3130 (mini picture attached with hyd. diagram) has an AnBo 5' grapple that seems to have very weak closing strength but terrific opening strength.
Also the hydraulics sound under extreme load/strain while closing the grapple even in mid air. The hydraulics are diverted from the bucket curl circuit (electric) but the bucket curl seems fine both directions.

I borrowed a pressure guage from the dealer and checked the pressure and it seems fine at the one point I was able to test (2400 PSI ...close enough). I attached a diagram for the layout of the dual cylinders and hoses to help makes sense of this.

One of the things I wanted to do was reverse the control direction with the diverter engaged. I thought it would be a simple swap of the hose connections at the grapple (see attached diagram). I expected the open to now be weak and the close to be strong....a tolerable arrangement for the time being. BUT instead the grapple would not longer open at all. I did this in the closed position so I could never check to see if the close was now strong. I put it back the way it was. /forums/images/graemlins/frown.gif

I do not understrand why reversing the hoses did not reverse the weak/strong direction. Also, with the grapple in mid air, I can close the grapple (it's weak, but it will close) but the Hydraulic pump sounds like it's under severe load/strain. When I do this same thing with the bucket curl circuit ( not diverted), theere is no strain at all as I would expect.

Something sounds like there is a partial blockage in one of the lines/cylinders on the grapple.

Any thoughts would be appreciated.
Thanks /forums/images/graemlins/confused.gif

om21braz · Jun 26, 2004

Re: FEL grapple \'close\' is weak...help please

I'd expect you have the hoses right for it to open and close - even if not forcefully both ways. Check the grapple off the machine and make sure it is'nt binding up itself in the close direction (easier said than done) - especially being the bucket curl seems to be working properly. Rule out the simple stuff first.

JerryG · Jun 26, 2004

Re: FEL grapple \'close\' is weak...help please

I just wonder if a flow reducer was placed in the line somewhere?

jmc · Jun 26, 2004

Re: FEL grapple \'close\' is weak...help please

Patk,

One thing to consider is that cylinders are stronger as they extend then as they retract. (cross sectional area of rod is not pressurized in retract). If you had margin pressure in the strong direction (close), it may be inadequate pressure in the open direction because of the reduced piston area. So the problem may have actually reversed in your experiment but you couldn't confirm it with the jaws closed.

If that pressure gauge caps off the line so there is no flow required for a reading, there might be enough flow past the obstruction to build up full pressure on the guage. But in cylinder use, the restricted flow would have to fill up the cylinder as far as the pressure could extend it before you got a meaningful reading. That may take awhile.

I suspect your diverter. You ought to get good support from Anbo. It appears to be a smaller company with their president tending the sales booth at one convention and later answering my phone questions. When management is in the trenches, the trenches seem to be cleaner.

John

LeRoi · Jun 26, 2004

Re: FEL grapple \'close\' is weak...help please

Someone will correct me if I'm on the wrong track, but wasn't there a thread about weak closing on a 4in 1 bucket and some serious technical discussion on regenerative dump circuits and the way they affect auxiliary hydraulic functions.

Jim_Fisher · Jun 27, 2004

Re: FEL grapple \'close\' is weak...help please

( wasn't there a thread about weak closing on a 4in 1 bucket and some serious technical discussion on regenerative dump circuits and the way they affect auxiliary hydraulic functions. )

I don't recall the thread but I learned very quickly to lock out the regenerative dump on my John Deere 4300 when using the 4in1 bucket. Mine would sometimes move in the wrong direction if I didn't.

Patk · Jun 28, 2004

Re: FEL grapple \'close\' is weak...help please

Thank you for the great insights.......it sure sounds like the regenerative dump circuit is causing the 'weak open' of the grapple. Finally something is making some sense.

The dump circuit control is what has been plumbed up to perform the grapple close function. In reading about it, the rod and base ends of the cylinder are being presented with just about equal pressure and the larger area of the base end is intended to win out, but at the cost of very little net force on the base end. Works swell when dumping a loaded bucket, but is absolutely NOT what you want for a strong grapple close.

I'll have to see if there is a way to disable the regenerative circuit, or perhaps avoid using the dump circuit all together for the grapple hydraulics.

Rip · Jun 28, 2004

Re: FEL grapple \'close\' is weak...help please

I have an AnBo 5' Grapple Rake mounted on a Power Trac 1845 that works just fine with full power in both directions. It is operated by the standard Auxiliary hyd circuit on the PT, no special or custom diversion was needed.

So, I would guess the problem lies in the diversion (or regen/dump function) circuit somewhere.

Good Luck, I am really impressed with my unit.

Rip

Patk · Jun 30, 2004

Re: FEL grapple \'close\' is weak...help please

Well after learning more about the 4-way control for the loader and the regenerative dump circuit, I now know exactly why the grapple close was weak....I did not push the control stick far enough to the right to "turn-off"the renerative dump.

The set-up is far from optimal for gathering a load in the grapple though. I really wanted to have the bucket curl (roll-back) stick direction also be the stick dirtection that CLOSES the grapple, but the regenertive circuit does not allow for that. I had to settle for the curl/rollback to the left, and the grapple close (while depressing the diverter switch) to the right.

It makes for an awkward set of motions:
1. forward gathering slash in grapple while slowly curling grapple (stick left as you go forward)
2. stop return stick to center
3. depress button AND THEN move stick right to close grapple
4. WHILE still depressing diverter button return the stick to center
5. go back to step 1 and repeat till load is gathered and secured in grapple

If you make the mistake of releasing the grapple button while trying to close with stick right, you jump into bucket dump and drop the load most times.....very diffiuclt to do smoothly and reliably.

So....I asked the Dealer Service Manager about a non-renerative spool valve for the dump circuit and got this long confused commentary on how I should shorten the joy stick so the left-to-right motion is shorter....sigh.

I went home and switched the grapple diverter over to the boom circuit (non-regenerative) and now have nearly mastered the boom-up/grapple-close diverter botton. A mucj better arrangement than the regen-dump circuit.

Jim_Fisher · Jun 30, 2004

Re: FEL grapple \'close\' is weak...help please

Patk,

( I now know exactly why the grapple close was weak....I did not push the control stick far enough to the right to "turn-off"the renerative dump. )

Can you confirm that this will work if you push far enough to the right? On my Deere 4300 the regen doesn't activate until you move the joystick far right. Not sure that it would be very practical to have it work the way you describe since the fast dump would only happen when you feather the stick.

Sometimes folks transpose things when explaining how something works. If this is the case, then you should be able to fabricate a lockout device - a physical stop - to disable the regenerative function.

( I really wanted to have the bucket curl (roll-back) stick direction also be the stick dirtection that CLOSES the grapple, but the regenertive circuit does not allow for that. I had to settle for the curl/rollback to the left, and the grapple close (while depressing the diverter switch) to the right. )

I agree. When my tractor was delivered the 4in1 was set up so that the curl also opened the bucket. I immediately switched the lines. Close/curl - open/dump is the most intuitive way for this to work.

( So....I asked the Dealer Service Manager about a non-renerative spool valve for the dump circuit and got this long confused commentary on how I should shorten the joy stick so the left-to-right motion is shorter....sigh. )

The three hardest words to learn are "I don't know". They should always be followed by "but I'll find out". Unfortunately, some folks never learn them and tend to fabricate some sort of imagined solution off the top of their heads. Shortening the stick will make things harder to control - not easier.

At this point, two things are obvious.

1) It doesn't work the way that you want it to work.
2) The service manager knows less about the problem than you do.

Hopefully someone who has a good understanding of your tractor's regenerative dump circuit will be able to jump in and help. If not, then you will have to aquire that knowledge.