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Loader works

deansa Join Date: Jul 2003 Posts: 4 Fort Erie, On. Canada

2003-06-23          58149

The loader that I,ve installed is complete and working and have cycled fairly well. My question is that the 3 point hitch does not work like it did before the loader being installed. The tractor is a Yanmar 155D, loader shop built using double acting bucket cylinders, single acting lift cylinders, and double spool, open center valve. I have yet to make final adjustments to the new relief valve, awaiting new pressure gauge'', but it is backed off until then. Also I notice that when the bucket cylinder is backed off completely, the valve handle ''snaps'' differently then the loader handle.

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Loader works

TomG Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley

2003-06-23          58151

I have to guess that the loader valve assembly is spliced into the high-pressure line going to the 3ph and that the valve doesn't have a separate low-pressure (TANK) return line directly to the reservoir. I seem to recall an earlier discussion and it sounds like you've straightened out the valve question and the project has proceeded well.

There are a couple of ways the 3ph could be affected. Many valve assemblies have relief valves in their inlet sections that are separate from any circuit relief valves. These relief valves would see pressure developed by a 3ph load and may open (especially if the settings were backed-off) so the 3ph may seem to have little power.

The loader valve is installed ahead of the 3ph and for valves with TANK returns operation of the loader cuts off oil flow to the 3ph so the 3ph will not lift while the loader is operated. For valves without a TANK return, the cylinder exhaust oil goes back into the high-pressure line. If the 3ph is in lift mode during a loader operation the loader cylinder exhaust oil goes into the 3ph lift cylinder. The pump then is lifting both the loader and 3ph loads.

I'm not sure how the single acting lift cylinders and valves are set up. I suspect that for lowering they simply open a port to the high-pressure line and exhaust oil simply is added to the normal open center flow. I am not sure what would happen if the loader was lowered while the 3ph was in lift mode. I think I've seen some single acting cylinders that have separate feed and return lines. There may be a check valve in a return line but if there were then the loader lift probably wouldn't as a float if placed in lower mode.

This is getting long so I'll save any thoughts about the valve handles.
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