Backhoe boom struggles to go up, drops when feathering up

[dirtyb115]

Hi all. I have a new to me RK37 with the backhoe option. I was using it the other day to dig a couple of holes for some new trees and it was barely able to get the boom all the way up especially if the other cylinders were extended. I had the rpms up around 2000. I also noticed that when i try to go up with the boom very slowly it actually drops. If i go faster, it drops a small amount before going up. Any ideas on things i could check/try?

I was also curious, should the stabilizers be capable of lifting the tractor off it's rear wheels?

Thanks!

 

[Roadworthy]

Slow or weak hydraulics are sometimes caused by having the three point in the full up position. Be sure yours is not quite full up and see if anything changes. If that was the source of the problem a slight adjustment to the rock shaft is in order. The stabilizers may be able to lift the rear wheels off the ground depending on their length and placement.

 

[YanmarFever]

Are there any leaks, also unplug the couplers blow them out with an air hose, (watch the O- rings) and plug them back in.
Do you have enough hydraulic fluid, check the dipstick.
Also check your 3 point lift lever that its in neutral, it could be in a conflict with the pump and the hoe if its in the up mode (back)..

Also what Roadworthy mentioned , the rockshaft lever, the one between your feet, below the front of the seat, screw it OUT to the left all the way.
Keep us posted

 

[dirtyb115]

Slow or weak hydraulics are sometimes caused by having the three point in the full up position. Be sure yours is not quite full up and see if anything changes. If that was the source of the problem a slight adjustment to the rock shaft is in order. The stabilizers may be able to lift the rear wheels off the ground depending on their length and placement.

Thanks for the reply. Three point is in the down position.

 

[dirtyb115]

Are there any leaks, also unplug the couplers blow them out with an air hose, (watch the O- rings) and plug them back in.
Do you have enough hydraulic fluid, check the dipstick.
Also check your 3 point lift lever that its in neutral, it could be in a conflict with the pump and the hoe if its in the up mode (back)..

Also what Roadworthy mentioned , the rockshaft lever, the one between your feet, below the front of the seat, screw it OUT to the left all the way.
Keep us posted

No leaks. Hydraulic fluid is not low.
I have an auxiliary hydraulic switch. It seems position 1 is for the 3 point lift, position 2 is the backhoe currently. I have it in position 2.
I have the rockshaft all the way left.
I'll unplug the couplers and try that.
I just ordered a pressure test gauge, but it won't be in for a few days.
Thanks

 

[oldnslo]

Is that the only function acting strange? Dropping before raising sounds like a load check leaking but that should not prevent lifting fully.

 

[YanmarFever]

Your on the right path. Have you checked your remote position lever to make sure the nut is tight that holds it on.
Dirty, does this machine have a small pto mounted pump to run the back hoe, or does it run off the tractor hydraulics ?

 

[dirtyb115]

Is that the only function acting strange? Dropping before raising sounds like a load check leaking but that should not prevent lifting fully.

Yes that's the only one. Rest of the backhoe seems to function as it should. The loader also works like it should

 

[dirtyb115]

Your on the right path. Have you checked your remote position lever to make sure the nut is tight that holds it on.
Dirty, does this machine have a small pto mounted pump to run the back hoe, or does it run off the tractor hydraulics ?

I don't remember anything being loose when I had the seat off the other week. I do remember looking at that assembly.

It runs off the tractor hydraulics.

 

[YanmarFever]

Well that eliminates a few things

 

[oldnslo]

Yes that's the only one. Rest of the backhoe seems to function as it should. The loader also works like it should

Since just that function I would look closely at that particular valve spool and linkage assembly to confirm nothing is loose or something jammed limiting spool travel.

Do you have access to a schematic for that back hoe valve? If yes that could provide some insight on other things to consider.

 

[dodge man]

I agree on unplugging and plugging back in any quick connects for the hydraulics. Sometimes they look connected but aren’t quite right.

 

[dirtyb115]

Since just that function I would look closely at that particular valve spool and linkage assembly to confirm nothing is loose or something jammed limiting spool travel.

Do you have access to a schematic for that back hoe valve? If yes that could provide some insight on other things to consider.

Only schematic that i can find is in the operator manual. (See attatched)

 

[oldnslo]

Thanks for posting the schematic. If it is accurate there are no load checks shown on any of the functions which I suspect is inaccurate but not an unusual occurrence to see general schematic vs detailed.
Is the valve accessible so that you can take some pictures of it? Someone might recognize it and be able to state there are load checks under these plugs.

 

[dirtyb115]

Thanks for posting the schematic. If it is accurate there are no load checks shown on any of the functions which I suspect is inaccurate but not an unusual occurrence to see general schematic vs detailed.
Is the valve accessible so that you can take some pictures of it? Someone might recognize it and be able to state there are load checks under these plugs.

Here is what it looks like

 

[oldnslo]

Dirtyb
In looking at those pictures of the valve it appears there is a plug between the work ports. I suspect that is the load check for each spool. If you are comfortable working on this I believe below that plug would be spring and either a check ball or poppet. After making 100% certain that the backhoe is in relaxed position I.e. all pressure removed, try removing the plug on the spool section that is failing and inspect that check assembly. Poppet stuck, piece of crud on seat, etc.

 

[dirtyb115]

Dirtyb
In looking at those pictures of the valve it appears there is a plug between the work ports. I suspect that is the load check for each spool. If you are comfortable working on this I believe below that plug would be spring and either a check ball or poppet. After making 100% certain that the backhoe is in relaxed position I.e. all pressure removed, try removing the plug on the spool section that is failing and inspect that check assembly. Poppet stuck, piece of crud on seat, etc.

Thanks for the suggestion, I'll take a look tomorrow if I have time. Appreciate the help

 

[dirtyb115]

Dirtyb
In looking at those pictures of the valve it appears there is a plug between the work ports. I suspect that is the load check for each spool. If you are comfortable working on this I believe below that plug would be spring and either a check ball or poppet. After making 100% certain that the backhoe is in relaxed position I.e. all pressure removed, try removing the plug on the spool section that is failing and inspect that check assembly. Poppet stuck, piece of crud on seat, etc.

Had a chance to take a look tonight. I pulled the plug, and as you suspected a spring/poppet. When i took it out the poppet stayed in the bore, and was sideways, but I am not sure if it was like that or it happened when i took the plug out. At any rate, i cleaned the seat, but didn't notice anything obvious. I don't think it fell over while reassembling, but having the valve block laying flat would make it a lot easier.

I started it up, and operated it a little in the barn, It was way better than before, but did notice it falling every once in a while when lightly lifting. (Maybe air still in the system? ).

With everything fully extended, it was still struggling to bring the boom all the way up, i had to curl it in before i could fully raise the boom. I did get my pressure gauges and fittings. Where should i be checking the pressure?
Thanks again for the help.

 

[oldnslo]

In looking at the valve pictures you posted it looks like there might be a plug that is connected to the “P” port. It is on right side valve in photo showing two sections and the “P” stamp on the casting. You could use that port or tee the gauge into the P line. This will provide pressure reading for all the functions. Run one function to end of stroke get reading, next, etc.

Looking at the complete valve photo The 2nd and 5th function might have work port reliefs. These are the silver hex fitting above the hose connection. They might be set lower than system relief so don’t panic if they show a lower pressure.

 

[dirtyb115]

In looking at the valve pictures you posted it looks like there might be a plug that is connected to the “P” port. It is on right side valve in photo showing two sections and the “P” stamp on the casting. You could use that port or tee the gauge into the P line. This will provide pressure reading for all the functions. Run one function to end of stroke get reading, next, etc.

Looking at the complete valve photo The 2nd and 5th function might have work port reliefs. These are the silver hex fitting above the hose connection. They might be set lower than system relief so don’t panic if they show a lower pressure.

Ok thanks hopefully I'll find some time this week to take a look. Also not sure if it's related but I have noticed that the boom wants to drop really fast if I'm not easy with the controls. Not sure if that's normal or not