3 point hitch low lift capacity

[mrakabota]

I have an L3410 Kubota. The 3 point hitch has very low lifting capacity. When I first start the tractor the 3 point hitch lifts OK, but after the tractor warms up the lifting capacity continues to decrease. In order to lift a small implement I have to rev the engine very high in order to get any lift. Depending on the weight of the implement, it may not lift at all.

Any ideas?

Thanks.

 

[85Hokie]

You had a fluid change recently? Checked fluid level? Last filter change?

For a 20 year old machine - has this been a problem, or JUST starting?

 

[mrakabota]

Thanks for your response. I've only owned the tractor 3 years. Bought from a private party. I changed the fluid and all filters last year after I noticed the problem. Fluid levels are good. I actually don't know if it has always been that way or not. The 3 point hitch worked when I bought it, but didn't check the load capacity.

Thanks

 

[TheOldHokie]

Thanks for your response. I've only owned the tractor 3 years. Bought from a private party. I changed the fluid and all filters last year after I noticed the problem. Fluid levels are good. I actually don't know if it has always been that way or not. The 3 point hitch worked when I bought it, but didn't check the load capacity.

Thanks

Do you have a loader or rear remotes on the tractor?

Dan

 

[mrakabota]

I do not have a loader.

I added a rear remote. Summit Manual Monoblock Spooler. Connected to the Hydraulic Block Outlet. I use this rear remote to operate a wood splitter. Running the wood splitter has plenty of power.

When not using the rear remote I turn the Control Screw to the horizontal position. Still the 3-point has very little lifting power.

Thanks again for your response.

 

[TheOldHokie]

I do not have a loader.

I added a rear remote. Summit Manual Monoblock Spooler. Connected to the Hydraulic Block Outlet. I use this rear remote to operate a wood splitter. Running the wood splitter has plenty of power.

When not using the rear remote I turn the Control Screw to the horizontal position. Still the 3-point has very little lifting power.

Thanks again for your response.

I thought this was going to be simple

By "control screw" do you mean the port selector on the hydraulic outlet block?

If yes can I assume you added a remote but it is not hot all of the time?

Dan

 

[mcfarmall]

Might be a bad piston seal on the 3PH cylinder. Works when the oil and cylinder are cold but when the cylinder warms up and expands and the oil is hot (and more runny) you lose lift capacity.

 

[mrakabota]

Yes that would be the port selector. It's called a control screw in the manual. It states to put in horizontal position when implement is not attached.

Thanks

 

[TheOldHokie]

Yes that would be the port selector. It's called a control screw in the manual. It states to put in horizontal position when implement is not attached.

Thanks

I think this is likely the source of your problem. As long as your Summit valve is connected to the outlet block that control screw should stay vertical. So lets talk about the plumbing on the Summit valve. How many hoses did you use to connect the valve to the tractor (not counting the ones that go to the log splitter) and where do they go? A picture of that plumbing would be very helpful.

Dan

 

[mrakabota]

I work on diagraming the Summit valve hookup this evening.

 

[TheOldHokie]

I work on diagraming the Summit valve hookup this evening.

Super - it does not need to be pretty. Could you also clarify how the log splitter is used? I assume it has it's own control valve and you use the Summit valve to feed the log splitter valve? I am also assuming the Summit valve stays on the tractor full time?

Dan

 

[mrakabota]

I've attached a picture of the Hydraulic Block Outlet on the Kubota and the Summit spool connection to it. In the picture of the Kubota hydraulic block, a letter is written on the hose connect indicating where the connection goes to the Summit Spool.

Kubota (1) Inlet -> Summit (N) Closed center port
Kubota (3) Outlet -> Summit (P) Pressure or Inlet port
Kubota (4) Tank port -> Summit (T) return to tank port

There is also a diagram of the Summit Spooler. Shows 2 valves but I only have one. And a diagram of the Kubota hydraulic block.

For the log splitter. I either tie off the Summit valve, and then operate the valve at the splitter. Or leave the splitter valve and operate the summit valve. Either way works.

Thank you so much for the help.

 

[TheOldHokie]

I've attached a picture of the Hydraulic Block Outlet on the Kubota and the Summit spool connection to it. In the picture of the Kubota hydraulic block, a letter is written on the hose connect indicating where the connection goes to the Summit Spool.

Kubota (1) Inlet -> Summit (N) Closed center port
Kubota (3) Outlet -> Summit (P) Pressure or Inlet port
Kubota (4) Tank port -> Summit (T) return to tank port

There is also a diagram of the Summit Spooler. Shows 2 valves but I only have one. And a diagram of the Kubota hydraulic block.

For the log splitter. I either tie off the Summit valve, and then operate the valve at the splitter. Or leave the splitter valve and operate the summit valve. Either way works.

Thank you so much for the help. View attachment 76386

I suspected you had something like this going on but I could not say exactly what. Now I think I see your problem - the hose plumbing is correct but you need a power beyond sleeve in the N port of the Summit valve. Despite what your documentation says that is not a closed center port. It is the power beyond (PB) or high pressure carry over (HPCO) port. Without the power beyond sleeve the N port is connected to the T port. So when you return the screw on the outlet block to the horizontal position the pump is connected to both tank and 3pt = no 3pt lift.

All you need is the power beyonf conversion sleeve shown below. Disconnect the hose at the N port, install the sleeve in the port, and reconnect the hose to the end of the sleeve. Now turn the screw on the outlet block to the vertical position and LEAVE IT THERE. You can use the Summit valve exactly as you are currently using it AND the 3pt will still work while the log splitter is connected. You can drop the log splitter and nothing needs to be changed. The Summit valve is still hot and can be used for for something like a top link if you wanted. The oil flow is as follows:

With the screw in the vertical position pump flow goes to P port on Summit valve, through the Summit valve and back to the outlet block via the N port. From there it continues to the 3pt and through that valve to tank. When you operate the Summit valve to use the log splitter the flow to the N port gets diverted to the log splitter, through that valve and back to the Summit valve and from there to tank via the T port.

Dan

 

[mrakabota]

Thanks, that's very helpful!

I assume this will not fix my 3 point hitch capacity problem. Because when I have the control screw horizontal, the summit value is out of the circuit. The 3 point lift capacity is different issue, correct?

 

[TheOldHokie]

Thanks, that's very helpful!

I assume this will not fix my 3 point hitch capacity problem. Because when I have the control screw horizontal, the summit value is out of the circuit. The 3 point lift capacity is different issue, correct?

When the screw is horizontal the Summit valve is NOT out of the loop. The oil is flowing into both the P and N ports simultaneously and both are connected to the T port and your pump is dumping straight to tank through the Summit valve. Thats why you have no 3pt lift. Install a power beyond sleeve in the N port on the Summit valve and leave the screw vertical at all times.

One thing that concerns me is the swivel fitting you have installed in the N port. Assuming that is one of Summit's P40 valves that port has either BSPP or SAE threads and there are two different power beyond sleeves.. If you screwed a SAE-10 fitting into that port its the SAE variant and you need the SAE sleeve. You might want to consult with Summit to make sure you get the correct sleeve.

Power Beyond Adapter Sleeve for P40 & Z50 Series Summit Monoblock Valves

Power Beyond Adapter Sleeve for P40 & Z50 Series Summit Monoblock Valves - FREE SHIPPING

summit-hydraulics.com

Power Beyond Adapter Sleeve for P40G Series Summit Monoblock Valves

FREE SHIPPING Power Beyond Adapter Sleeve for P40G Series Summit Monoblock Valves

summit-hydraulics.com

Dan

 

[mrakabota]

Found the power beyond plug on the summit website. I will order and give it a try. That would be great if that fixes my 3-point lift problem!

Thank you! I will update this once I get it install.

-Mike

 

[TheOldHokie]

Found the power beyond plug on the summit website. I will order and give it a try. That would be great if that fixes my 3-point lift problem!

Thank you! I will update this once I get it install.

-Mike

Make sure you get the one that matches your valve!!!! I will be happy to take bets on it fixing your problem

Dan

 

[mrakabota]

I found a P40 stamped on valve.

 

[TheOldHokie]

I found a P40 stamped on valve.

Summit has been selling them for quite some time and they are pretty easy to visually ID They recently switched suppliers and the new P40s have different port threads. thats why you need to make sure you get the correct conversion sleeve.

Dan

 

[mrakabota]

Hello Dan,

Good news! I installed the power beyond plug and it fixed the problem!! My 3-point lift capacity is back.

Thank you so much for the help.

Question, would it hurt anything to hold the Summit lever active, and operate the splitter with the lever on the splitter cylinder? I would just tie off the summit lever with a bungie or something.

Thanks,
-Mike