Pump ID help

[Roehm Farms]

This pump is off of a JD 55 combine I think I'm not finding much info on the web for it. I am most curious about the two pressure lines coming off of it. There is some kind of valve in the back of the pump that I am not sure what it does. I can spin the pump by hand and pump oil from the street ell to the small line, but can't build enough pressure (with shop air) to get the valve to shift and get any thing out the big pressure line.

Thinking of using it for a log splitter build.





Thanks for any help,
Jeff

 

[oldnslo]

Looks like and old gear pump and the valve in question could be a priority flow valve used for steering or some other "situation critical" function. The street el could be the excess flow port which would not see flow until a given flow rate of oil creates a pressure drop and shifts the spool. I don't think you will get it to shift using shop air.

 

[Roehm Farms]

Thanks oldnslo, you are correct. Just found some info on jdparts. The small (3/8) pressure line goes to the steering valve and the large (1/2) pressure line feeds the rest of the hydraulics. The street ell is the inlet. The pump should be a Cessna 20270-OPKK, I'm not finding any pressure or flow data for it anywhere online, or what split the priority valve would have. I am kinda hoping to run the splitter cylinder valve from the priority side and a log lift and hydraulic winch from the other side. But it seems I would need a closed center valve on the priority side to get flow to the other output. Am I thinking correctly?



Thanks, Jeff

 

[oldnslo]

Jeff,
I would suspect that once the flow rate of the pump is greater than the flow required from the priority port all of the excess flow will be directed out the excess flow port. The priority flow port attempts to provide a constant flow rate with varying engine speeds which provides a more constant steering speed.

I would have to look at the actual valve function but on some priority valves blocking the priority stops ALL flow which is a bad thing with fixed displacement pumps like this. Being safety conscious I would recommend a relief valve on each pressure port of this pump.

Eaton purchased Cessna years ago so Eaton tech support or an Eaton distributor might be able to tell you what the size of that pump is and what the priority flow is set at. May also be proprietary information since it was for JD.

 

[Roehm Farms]

Thanks oldnslo, I tryed contacting a Cessna/Eaton dealer, all they could tell me was the pump was only made for Deere.

I am hoping I could cross reference the pump gears and find a flow rating.

Here is the pump schematic if anyone can tell how the priority valve should operate.

Thanks, Jeff

 

[CJONE]

Oldnslo is correct on the priority valve on the back of the pump. I have made good money on replacing them with 2 circuit pumps. Do yourself a favor and buy a splitter pump. A 16 gpm unit is around $140 dollars. CJ