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Hello all! I am hoping someone who is good at hydraulics can help me out. I just purchased a Simplicity 9518 4x4 with 3-point hitch and a front end loader. For some reason (which I don't understand) there is a selector valve that controls these systems. I have to move the valve in one position to use the front end loader and then move the selector valve into the other position to use the 3-point hitch. Why?

Next, for some reason the front end loader will not lift up unless the engine is running at a very high speed. There is no lifting capacity either. I'm going to check the pressure at the pump tomorrow, just received the gauges today. I believe it tis good right now since the 3-point hitch works properly and the tilt on the front end loader also works good. Just before I purchased the tractor, the last owner had a new control valve installed for the front end loader thinking this was the problem. It did not fix the problem.

does it matter if the fluid goes to the 3-point hitch before the front end loader or not. I've looking at hydraulic system examples on the internet and from what I can tell it should not matter. It seems to me that if I have a return line hooked up to the system for returning the fluid when nothing is being used that I should be able to get rid of that selector valve.

This is a open hydraulics system. Any help would be appreciated.

Thank you!

chysm60
 

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If you have a manual that shows the schematics for the hydraulic system, a review may show why there is a selector valve. Is there a control valve specific to the 3PH or does it use the loader valve for the 3PH as well as the loader? Where in the system is the relief valve?

Do not screw the gauge directly into the pump for checking the pressure . . . unless you want to buy a new pump. Some control valves have a gauge port at the inlet side of the valve body, otherwise install a Tee fitting at the inlet side of the loader valve (or selector valve, whichever is first in the circuit) and use the extra branch of the Tee for the gauge.

I'm making a WAG here about the loader lifting speed and low lifting capability, one or both of the cylinders is due for a new set of seals.

For your third concern, a review of the schematics will indicate the flow direction and which control valve is first. You are correct in that it shouldn't make a difference on which gets fluid first, but much depends on the location in the system of other components, specifically the relief valve and whether or not there is a need for a power beyond kit for the first control valve in the system. Incorrect plumbing can cause pump breakage if both the 3PH and the loader are operated at near capacity loads at the same time. A correctly designed and plumbed system will operate as you suggest.
 

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Discussion Starter #3
I do have the manuals for the tractor. The 3-point hitch (3PH) is integrated into the tractor housing. As you can see in picture 1, the upper left shows the hard line coming from the pump right into the housing. In pictures 3 you can see the shaft coming from the control lever for the 3ph in the upper center of the picture. In picture 1and 2 you can see the poppet valve that is attached to the housing. As you can see a distribution block was added between the housing and the poppet valve. Picture 10 shows the breakdown of the poppet valve. I am assuming that since here it is called a poppet valve that this is the relief valve. From the distribution valve the lines go to the selector valve, picture 4. From the selector valve lines run back to the poppet valve and the front end loader (FEL) control valve. Picture 13 shows the breakdown of the FEL control valve. Now valve.

I am going to install a pressure gauge (for testing only) with a tee, into the line coming from the pump and another gauge on the loader valve to see if it is loosing pressure somewhere. At least then I can tell a little of what is going on in this system. I also want to make sure that I am getting 2000psi pressure to the system before I start rebuilding cylinders. That is a good idea about the cylinders rings being bad, I didn't think of that.

I have included a few extra pictures of the system, maybe someone can help me out. I would really like to get rid of the selector valve, it is a nuisance switching back and forth. I grew up as a farmer and we never had to do anything like that on any of our tractors. Some of our tractors were from the 50's when I was young and this is newer technology. The 3PH seems to have plenty of power so far, I only have a back blade and a rear finish mower with it.

Now, just so you know, I'm quite good at mechanics, just not hydraulics. I had to purchase two tractors to put one good one together. The engine had to be changed since the simplicity didn't run. I purchased a MF1010 with a good engine in it and swapped them out. I will rebuild the simplicity engine in time, just didn't want to do it right now. so with the MF1010, I do have some extra parts to work with. The simplicity is a 4x4 and the MF1010 is 2wd with no implements.

Thank you for responding! I can really use the help on the hydraulics.

chysm60
 

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Okay. I suggest that you talk to someone familiar with the hydraulic system on that tractor, specifically with regards to the internal porting of the 3PH relief (poppet) valve in the housing and how the selector valve works for its ports when shifted. That seems to be why it is set up the way it is.

I believe that there is a way to get the operation that you want, but would need some time for studying the porting on the distribution and selector valve to be sure.

If I'm right, and that's a big IF, here is a flow chart that should work. Keep in mind that there is no guaranty that it will actually work, and it may cause other issues.

First, both the loader valve set and the 3PH are equipped with relief valves, and the loader relief is factory set to 2500 psi (adjustable from 2000 - 3500 psi). This is a good thing since the 3PH relief is set for 1990 psi.

Second, the loader valve set is capable of power beyond, but you have to buy and install the kit first and reroute the existing return hose back directly to the reservoir.

Third, remove the distribution valve and the selector valve can be removed at your discretion. If left in place, remove the hoses and cap off the ports to keep dirt out.

Fourth, the plumbing flow chart.

Pump > Loader valve set > (from the power beyond port) 3 PH
.................................. > (from the return port) Tank

I think that that will work. Note that I am not a hydraulics expert, or familiar with the ins and out of specific tractors. I am well versed in the basics of open center hydraulic systems as applied to small tractors and similar equipment.

Please post your results.
 
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