Go Bottom3 ph not working
 | deansa
Join Date: Jul 2003 Posts: 4 Fort Erie, On. Canada 
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2003-07-07 59025
I have finished installing fel on my yanmar, works great
but when I installed my 3 ph mower, it will not lift, but rather lift the loader and bucket when 3 ph valve is activated. Any thoughts as to a solution / remedy. This discussion board has been great in answering a number of questions, Thanks to all who take the time.
deansa
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| jamtrac2003
Join Date: Jul 2003 Posts: 9 honesdale, PA
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2003-07-07 59030
You didn't say what model tractor you have. It may be something unique to that model. But usually that happens when the pressure relief on the loader is set higher than the pressure relief on the 3 pt. hitch. Gary J. ....
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| deansa
Join Date: Jul 2003 Posts: 4 Fort Erie, On. Canada
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2003-07-07 59032
Sorry for not mentioning the model, it is a Yanmar 155d
and the valve that operates the loader is a Yale, double spool. I have backed out the relief valve ,''fine thread screw with a jam nut'' I am assuming this is the relief valve you mentioned. Thanks again, deansa ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley 
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2003-07-08 59110
Well, when the 3ph is operated the return line to the reservoir is closed, flow is diverted to the lift cylinder and works against the load to develop pressure. That pressure is 'seen' the entire length of the high-pressure line back to the pump. If there's a passage to the loader cylinders and the loader load is lighter than the 3ph load then the loader will move but the 3ph won't.
This has got to be true almost by definition. The why it's happening is another question. The loader relief valve mentioned by jam may be a possibility if the relief valve is for the loader cylinder lines rather than the high-pressure line (could be both I suppose).
If you backed out the relief valve completely it may open a passage between the loader cylinder and high-pressure lines in which case high-pressure due to a 3ph load the loader cylinders would see pressure and they would move if there's little weight in the loader. If both lines to each cylinder see pressure the loader would operate like a regenerative circuit and the cylinders would extend.
So far this is all theory and my reasoning is going in the opposite of jam's. It could happen because the loader relief is lower then the 3ph relief, but we're in the same ballpark. I think jam's idea would be true if a loader valve and the 3ph were operated at the same time.
So much for theory, and here's where it gets tricky. The loader valve may not be power-beyond rated. A valve with a single outlet may or may not be power-beyond rated. The issue is important. If the valve isn't PB rated then parts of the valve may be exposed to pressures they aren't designed to withstand. It would be tempting to test the theory by extending both loader cylinders to max (if that's the direction they move) and then trying the 3ph. If the theory is right, the 3ph should work normally. However, the valve might be ruined in the testing unless it's PB rated.
I think the loader valve specs should be checked before the relief valve is increased. If it's not PB rated, increasing the pressure above the 3ph relief pressure may be a partial solution but then the loader and 3ph should never be operated at the same time. Maybe Yale can supply some tech support for the valve used in this configuration. In addition, some valves are sold with a plug that must be removed for use in open centered systems. ....
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 | lsheaffer
Join Date: Jun 1999 Posts: 1082 Northern Illinois 
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2003-07-12 59388
Before trying to diagnose your problem, I need to know how the loader is plumbed. Many of the problems occuring after installing a loader is due to improper plumbing. If you want you can email me a diagram. ....
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| deansa
Join Date: Jul 2003 Posts: 4 Fort Erie, On. Canada
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2003-07-14 59488
This is how I plumbed the loader valve to the tractor hydraulic system. cut pressure line from tractor pump and installed into inlet port on loader valve, outlet port from loader valve then tied back into other end of pressure line that runs to 3 ph valve. The existing return line did not change except that an additional oil tank was built into the design of the loader frame and a spin on cartridge filter installed. Thank You deansa ....
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| lsheaffer
Join Date: Jun 1999 Posts: 1082 Northern Illinois
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2003-07-15 59520
So you have a power beyond valve with 3 hoses. Usually on a power beyond valve the out goes to the reservour & the PBY goes to the 3 point. Yours is hooked up backwards from the usual installation according to the way I interpret your message. . When you activate the 3 point the only way the oil can get to the 3 point is by leakage in the the valve & through the loader cylinder circuits. The PBY line should have oil flowing when the valve is not activated. The out line should only have flow when the loader valves are activated. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2003-07-15 59530
From my reading of the Dean's comments I thought the valve had a single return line, and that type of valve may or may not be power-beyond rated. It's sure something that needs to be clarified before the problem can be diagnosed.
If it is a two return hose type, connecting it backwards would dump the pump flow directly to the reservoir when no loader valve is operated and the 3ph wouldn't work. If a loader valve is operated, cylinder exhaust oil from the loader would go to the 3ph. If the 3ph is in neutral or lower mode, the oil would go through the hitch to the sump and the loader would work fairly normally. However, if the 3ph is in lift mode and a loader valve is operated the both the loader and 3ph would move. However, there may be enough pressure developed in the return line to damage the loader valve.
I'm not clear on how the reservoir in the loader frame is connected or its purpose. ....
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