kioti 1200 backhoe hydraulics

[rlpearce]

New guy here, looking for answers to my hydraulic problem. I purchased a Kioti 1200 backhoe which came with a small PTO pump. I mounted it (3 pt.) onto my old Massey 35 and removed it's much larger PTO pump in order to put the smaller one on that came with the backhoe. The backhoe worked great (after I installed a splitter valve so I could direct pressure to the FEL or the backhoe) but the FEL was VERY slow and had little lifting power. I then removed the small PTO pump and put the larger one back on. Then the FEL worked properly again but when I switched the splitter to the backhoe it would load the engine and the backhoe was noisy and had little power. I assumed I was overloading the backhoe system so I bought and installed a Prince adjustable relief valve and put it in the backhoe line just after the splitter. If I back it off all the way then the tractor doesn't load up but the backhoe has no power, which makes sense. But as soon as I start to increase the pressure at all, the engine will load whenever I select the backhoe, and the backhoe still has very little power, nothing like when the smaller pump was used. I don't know if the Kioti backhoe is open or closed center, I assume the tractor is open. I wrote to Kioti to ask what the operating pressure was supposed to be, but they didn't even answer me. Hopefully one of you that knows hydraulics better than I do can help. I need both the FEL and the backhoe to work, but right now it's one or the other. It also would be great if I could find a source for a manual for the backhoe.

 

[Leejohn]

Sound like you are not using the PB port coming off the BH to feed the BH.

 

[J_J]

Most of the Kioti KB backhoe pressure rating is 2466 psi.
-------------------SB ------------------------------1875 psi.

It is hard to follow exactly what you did with the hyd.

A PTO pump and valve has it's own hyd circuit.

The pump has a pressure rating and that will determine the power. The pump GPM will determine the operating speed.

What is the pressure reading using the PTO pump, and the cyl fully extended.

What kind of splitter did you use?




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[Coyote machine]

Welcome to TBN.:thumbsup: Sounds like Leejohn may be on the right track. PB=power beyond, BTW.
I'm not a hydraulics guy so I'll bow out. Good luck.

 

[J_J]

If he is using a PTO pump, that is a separate circuit.

Not even sure where the splitter is being used.

 

[J_J]

Sound like you are not using the PB port coming off the BH to feed the BH.

Don't understand what you are saying here.

 

[rlpearce]

OK, I'll try to be more specific. Originally, the tractor used a PTO pump that was plumbed pressure side to the valves (FEL only), other side of valves to tank, tank to PTO pump intake. FEL worked fine. Originally the backhoe was plumbed with it's own (smaller) PTO pump and it's own tank. When I hooked up the backhoe I did not use the backhoe tank. I did use the smaller PTO pump and used a tee to supply both the backhoe and the FEL, with two separate returns to the tank. That didn't work, as pressure could go back through the tee and other set of valves (and back to tank) when operating either the FEL or Backhoe. That's when I install the (manual) splitter valve, simply selecting the pump output to go either to the FEL valves or to the backhoe valves, both still having their own return lines to the tank. That worked fine for the backhoe, I was actually amazed at how much power it had. But the FEL was then very slow and had very little lifting power. I figured the pump was too small. By the way, I used to be a professional auto mechanic (20+ years) so I'm OK with most mechanical things, I just don't have that much experience with hydraulics, other than brakes. So back to the backhoe. Since I figured the pump was too small, I put the larger PTO pump back on and plumbed it exactly the same way as the smaller pump had been. Output to splitter, inlet from tank, both valve sets with return to tank. Now with the FEL selected with the splitter, the FEL worked fine again. But when the backhoe circuit was selected, I got a decrease in RPM's and the engine was obviously loading, with all backhoe valves in the neutral position. The backhoe valve body was also now noisy. (it wasn't with the smaller pump) I figured I was overloading the backhoe, either with pressure or volume. So I bought and installed a Prince adjustable relief valve between the splitter and the backhoe valve set. The relief valve dumps excess back to the tank. With the relief valve backed all the way off the engine doesn't load, but the backhoe doesn't work either. As soon as I start putting pressure on the relief valve spring, the engine will start to load, I still have noise at the backhoe valve body, and although the backhoe works, it has very little power. I haven't cranked up the relief valve for more pressure, because I don't want to damage the backhoe controls, not knowing exactly what is going on. I don't have a pressure gauge on the system, so I don't know what kind of pressure either pump is putting out. The original PTO pump is at least twice as large, physically, as the backhoe PTO pump. If I'm not explaining the plumbing well enough, I can try to make a drawing and figure out how to post it on here.

 

[J_J]

If the engine is working hard using the pump. then something is blocking the flow.

On some of the splitters, the Excess flow has to go to tank, so please provide the model number and name of the splitter.

The size of the pump only dictates the operating speed.

The higher pressure pump will provide the most power.

I think your problem is in the splitter.

 

[Leejohn]

Yes I would say now the spltter not plumbed right or something wrong with it. How many ports are on the splitter?

 

[rlpearce]

I don't remember for sure but the splitter appears to be this one, with the standard selector spool.
Prince Hydraulics > Products > Hydraulic Valves > Selector > Model SS

All this splitter does is to direct pressure to one port or the other. And it (the backhoe) works perfectly when using the smaller pump with the splitter. I only have a problem with the backhoe when I put the larger pump on. I don't understand how the splitter can be the problem, can you enlighten me please? Always willing to learn.

 

[Coyote machine]

My DK-40 se/HST tractor, with Kioti hoe, KB-2485, uses the tractor's hydraulic pump, and is controlled by a detented lever that engages the hoe's hydraulics. If I try to use the FEL while the hoe circuit is engaged I get reduced and slower lift then normal. I mention this because I think you need to find a way to shut off the hoe when not in use, and especially when wanting to use the FEL.

 

[rlpearce]

That is exactly what the splitter is for, and does. When using the backhoe there is no power to the FEL and vice versa.

 

[J_J]

Why are you not using the tractor hyd for the FEL, and the PTO pump for the BH.

Still don't know why the splitter is being used. Again, what kind of splitter are you using.

If the FEL is the first valve in the hyd flow path, it can use all of the fluid the pump produces and leave no fluid for the BH.

If you are trying to use the BH and the FEL in the same circuit, then the first valve will have priority, and if using the BH only it will provide back pressure and affect the FEL valve when you try to use it.

If the BH is only using the PTO pump, it will have no effect on the FEL hyd.

This kind of splitter will provide equal flow to two circuits.

3/4" NPT 16-30 GPM DIVIDER VALVE

This is a priority flow divider and will keep the priority flow the same. The remainder of th eflow will go to Excess flow.

6/30 GPM PRINCE PRIORITY FLOW DIVIDER W/RELIEF

 

[rlpearce]

The tractor has no hydraulics except for the PTO pump. At least, none that operate the FEL. I'm not sure what operates the 3 point hitch, it operates independently of the FEL or the backhoe. The splitter is used, I believe, because if two sets of control valves are on the same circuit, in parallel, when you attempt to apply pressure at one set, the fluid has a path through the other set with no resistance. So this splitter applies pressure to one set or the other, not both at the same time. The FEL and backhoe both would not work when I had them connected in parallel. After I put in the splitter, the backhoe worked fine on it's own circuit with the smaller pump. What I don't understand is why it doesn't work with the larger pump, even with a pressure relief valve to dump excess pressure back to the tank.

 

[J_J]

If you use the right splitter, you will have two individual circuits, and can operate two valves at the same time.

For instance, your tractor has a 10 GPM flow, then each hyd circuit will get 5 GPM.

Again, please post the name and model number of the splitter you are using.

Did you understand how the splitters worked in my above post.

Are you using a splitter of a selector valve like this?

3/8" NPT 20 GPM PRINCE SELECTOR VALVE.

If the FEL valve has a PB port why is it not feeding the BH?

 

[rlpearce]

I think the splitter is a Prince SS, with the standard spool
Prince Hydraulics > Products > Hydraulic Valves > Selector > Model SS
I understand how the other splitters work, that is not how this one works.
I don't know if my FEL valve has a PB port or not. (This is an OLD tractor, BTW)
I'll look into that. Also, really don't mean to be beating a dead horse here, but the FEL and backhoe each have a separate return line that goes through a filter and into the tank, so when I select the backhoe circuit it certainly seems that is should not be loading the engine when all valves are in neutral. I don't mind having the manual splitter, and not being able to use the FEL and backhoe both at once, as I couldn't anyway. If there was physically room to do it, I'd install a PTO extension and use both pumps, but there isn't quite enough room.

 

[J_J]

That valve from Prince is a selector valve, not a splitter.

It will provide a flow path to two circuits, one at a time.

If the PTO pump is feeding that valve and you have the BH selected, you should get the full flow and pressure developed by the pump and BH.

If the FEL is selected, then the FEL should get the full flow and pressure developed by the pump and FEL cylinders. Your FEL PB port should be plugged so all flow exits the OUT port.

You might check those filters and see if they are free and clear and not making back pressure .

If the PTO pump is made by Prince, the max psi is only 2250 psi.

How large a PTO pump are you trying to run with your engine?

If the BH loads the pump in neutral, things are not plumbed correctly.

Can you draw out your flow path?

 

[J_J]

Hydraulics:
Capacity: 8 gal [30.3 L]
Pressure: 2800 psi [193.1 bar]
Pump flow: 3.5 gpm [13.2 lpm]

You tractor has enough hyd power 2800 psi to operate a FEL, and has more pressure than the PTO pump 2250 psi.

Tractor hyd might be slow but should lift more that when using the PTO pump.

You should have more power using tractor hyd with the BH, although slower.

What is the GPM on the PTO pump and what rpm is it turning?

 

[rlpearce]

I understand that I could power the FEL and/or the BH with the tractor hydraulics, but I'd rather not do that. Firstly, if I understand correctly, I cannot use the 3 pt. at the same time as FEL or BH if I do this. Also, as you say, they would operate very slowly. I cannot answer your question regarding the GPM of the PTO pump, I don't have that information, and I cannot read make, model, etc. on it. All I can tell you is that it powers the FEL nicely, and that it apparently grossly overpowers the BH. My installation of an adjustable pressure relief valve did not solve the problem, so is it possible that what is needed is a flow control valve instead? One that dumps excess flow back to the tank? Perhaps the BH cannot handle the flow of this pump but it needs the pressure that it or the smaller pump that came with BH provides? Since the BH loads the engine with the valves in neutral, it only makes sense to me that the BH system is too small and restricted to handle the flow from this larger pump. If this is the case, would an adjustable flow control pump such as is used to control hydraulic motors work?

 

[rlpearce]

When I got the BH it had a filter on the return line. My tractor did not. Figuring this was a good time to get one on the tractor I moved the one from the BH to the tractor, since I was no longer using the BH tank anyway. Point of all this is, I just got to wondering if the filter is plugged or is the wrong one to handle the pump I'm using. It should just open an internal bypass if flow exceeds filter capacity but I wonder?