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| The PB is designed to connect to an external closed-center valve that can send an independent load-sense signal (LS) back to the PFC signal circuit, that can either accept the full flow the Pfc pump sends thru the outlet or can self-regulate the flow that is required by an individual circuit, and that can be commanded on/off by an external input. And do all this without creating issues with the other hydraulic circuits that are working at the same time. This is a very basic explanation, and I won't spend all evening talking about what is really involved in a multi-tasking PFC system.
Basically the PB was designed for something like a laser-controlled land leveler. The variable-rate drive valves on JD or CNH planters simply don't do all of the above things, because They are designed to use a controlled flow from the tractor remote valve, and they let the tractor remote valve take care of all the supply side control hydraulics. The planters VR controller decides how fast it wants an orbital motor to spin, and simply opens or closes a PWM solenoid to use less or more of the flow from the remote valve.
When you try to just plumb a supply & return to the VR circuit, it's about as crude as hooking a fire hose to your lawn sprinkler. Yeah, it sorta works but then try cycling another 3 or 4 sprinklers off/on from the same water hose and see what happens. Of all the circuits you don't want surges and pressure dips & spikes in, it's the VR drive!
You didn't say but we assume you want to use the PB because you ran out of remote valves due to all of the things you need to do with the planting rig. We usually see that operators want hook up one remote valve for frame fold/ transport. An easy way to get double use out of that valve is to mount an electrically- controlled splitter back on the planter tongue or frame. Run a set of hoses from the remote coupler to the splitter and have unswitched output feed the planter VR, or fertilizer drive, or whatever while planting. Then flip a switch to change to frame fold/transport hydraulics.
One other suggestion is that if you simply must use the PB, connect it to the least critical circuit that doesn't change speed hardly ever. Something like a rod weeder. You can rig a variable orifice on the supply hose and take your LS signal downstream of the orifice. Do not remove the small plug from the LS port, there are very few applications where that is done. | |
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Power beyond port question......
