Faunsdale, AL | sandhillsam - 5/30/2011 10:23
My 1980 4440 only has one hydraulic filter.
I thought ours was one of the oldest ones made! It's a powershift, so maybe that has something to do with it having the 2 long hydraulic/trans filters. I think with only one hydraulic filter a 40 series on up JD will still return oil from the SCV into the charge pump circuit to the main pump/oil cooler in front. If not, you need one of the filter covers that have an inlet tapped into it to return your flow from a loader valve or hydraulic motor etc. At any rate, you need to avoid dumping your high volume retun oil into the tranmission sump because the charge/transmission pump is only something like 9-10 gpm on a quad range and maybe 12-15 on a power shift, WHEN they're in good conditon and the filters are clean! Old ones with a lot of wear won't do that and if you also have some high pressure leaks to return in the SCV's, rockshaft etc, you can exceed the capacity of the charge pump pretty quickly while running a hydraulic motor or at least make any additonal function you need operate move really slowly.
But the main thing is the oil that the charge/transmission pump is pushing forward is mostly going into the front pump and out as high pressure flow and very little is going on into the oil cooler before returning to the transmission sump. Leaks and hydraulic motors never stop like other "normal" hydraulic functions, so the heat builds up worse when you have either or both.
A case drain line is plumbed into the seal area of a hydraulic pump sort of like the little plastic line JD puts on their front high pressure piston pumps. It drains the leakage that gets past the main seal of the pump and keeps it from building up pressure and pushing out past the shaft seal you can see on the outside of the pump. Our vacuum planter doesn't have one and we never knew not to shut off the pump by returning the lever to the middle for a year or two after we got it. It has done just fine so far, but now we're better educated and do it right. |
Hyd. sprayer pump on a 4440
