The lower port is the res dump port, it flows right into the resevoir. The upper larger port is the pump pressure line. The smaller port is the regulator line. The system works as follows... Pressure is fed into the regulator lines and acts on the safety vavle. when the safety valve sees full pressure in this line, it dumps the pump pressure into the resevoir. The system runs between 30 and 60 lbs this way. As soon as any movement is done to the valve, it creates a pressure drop through the regulator line and when the safety valve sees this, it causes the pump to instanlty build up pressure to the control valves. This is a hard process to describe without illustrations. I thoerize that if you cap the small port, and use the bottom port as a dump, and the top large port as the pump feed to open center control vavles, that it should work. The documentation I have here doesnt specifically say what the ports are or how they interact between the front and rear set.. However, all of the pressure control is done via the safety vavle, and removing it and using it as I said should work unless I have overlooked something. The ports on the resevoir should be NPT holes and should readily except fittings. If you do that, I would advise smearing some thick grease on the oring lands afterwards so they dont get corroded in case someone in the future wants to convert back. I believe if you have one hydratouch control valve which you want to keep, if you mount it on the safety valve and do as I said above that the system will also work. I really meant to map out the ports when I had the res cover off of mine, as that would give me a more definite answer for you. I can scan the 18 page hydraulic manual. It is not EXACT to the 300u (it is for the farmall 300 and 400 series which are pretty much the same design wise), but the system is basically the same and has taught me alot. I wish I could be of a more definite help.
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