70 Hydraulics

I have a 70 Diesel. On mine, and most of the numbered series, the Pow-R-Trol systems were equipped with remote cylinder breakaway couplings (Aeroquip ?) that eliminated that need to remove the plugs from the Pow-R-Trol to connect the cylinder hoses. This also eliminated the mess and oil loss every time you connected or disconnected the remote cylinder.

To facillitate switching between the rockshaft and cylinder, one of the two rear plugs (that you would have normally had to remove to connect your cylinder hose on an "A" or "B") has a special cap that has a selectable diverter valve inside. I can't remember if it's the top one or the bottom one, and my book is out in the garage, but I'm sure you'll see it...it has a seam were the cap meets the plug body. This "cap" screws off to reveal the valve. After removing the cap, you'll see a knurled knob that is either screwed in all the way to activate the rockshaft, or the remote cylinder, I can't remember which, but to make the opposite action happen, you'd turn the knurled knob out until it's shoulder nearest the tractor is even with the edge of the cap shoulder.

This allows you to switch between either rock shaft or cylinder, but you can't run both at the same time. When you get it switched to the remote cylinder, you'll be able to place the lever in the posion of choice (either forward or back depending how you hooked up your hoses), and operate your splitter. If you have a bypass at the valve of your splitter, you do no harm to the tractor, as the oil will always be circulating. If you don't, you'll want to to return the lever to neutral fairly quickly after the splitter cycles, as excessive by-passing will cause the oil to get fairly hot. Some of the folks on this board suggest that use of non-detergent oil in the power-trol will minimize foaming.

Hope this helps !

Frank-in-Tallahassee

70D // 855

Yep, a 3020/4020 had a separate lever for each function...one for the 3 pt. rockshaft, and one or more for each remote cylinder.

I don't want to confuse you, but the valve I'm referring to IS one of those plugs....you just might have to look REAL close to find the half of the knurled cap that screws off. Could be painted shut....that little knob valve is in there.

Reason I think you have one is that on all the early numbered series I've seen that have the outboard cylinder hoses, had that special plug, with the removable cap/selecter valve inside. It's possible that someone had lost the original and replaced it with another/non-selectable plug, but you can get yourself one from a salvage yard, and you'll be much happier.

I went out and got my book. If you have the JD Operator's manual (mine is the diesel manual OMR2032) it is under the section called "Adjustments for Breakaway Coupling and Selector Valve Operation". In my parts book it's called AA5724 R, Valve, Assembly, Selector.

Have you had this tractor long ? If so, you probably know more about it than anyone else will, but if it's relatively new to you, it might be worth taking a second look at things.

You could go to JD and ask to see the illustration of the selector valve assembly. It might make more sense then.

Frank-in-Tallahassee
70D // 855

A big 10-4 on that 70 liking it's gas !

When we got this 70D in 1969, it was our first diesel, and as you know, it was one of the thriftiest designs on fuel.

Our record was cultivating 80 acres of corn and beans on one 20gal tank ! That tractor really benefitted from a fuel gauge as you could be lulled to sleep as to when it needed refilled. Our 48 A with high-comp aluminum pistons ALWAYS needed filled at mealtime.

On your selectable plug, good news is that since they're the same on the 50-60-70, they're available all most everywhere.

Good luck !

Frank-in-Tallahassee
70D // 855