620 Hydraulic question

Joe Way

Member
My 620 has the 45 loader with factory double-acting cylinders on the bucket. I have converted the boom cylinders to double-acting as well. The attached photo show the hydraulic connections. Pressure to the loader valve is from the lower breakaway coupling and return from the valve is into the top of the reservoir. The Remote Cylinder Operating Lever is all the way back for loader operation. This setup works great.

I am considering buying a backhoe attachment and will need to hook up a separate pair of lines. I can't find enough information in the 620 Operator's Manual or the 45 Loader Manual to tell me for sure how this will work. I am thinking the pressure out to the backhoe valves will come off the upper breakaway coupling, and the return from the backhoe valves will need to go into a T with the return from the loader valve.

I'm hoping someone can confirm this for me, or tell me what will work. Thanks.
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I have no idea why the return line is in the "Fill Opening"..!!!
The return line (for a Double Acting cylinder) should be in the return line...

If you install a Dual Hydraulic Remote to your 620/630, you can operate each independently..

Ron..
 
Ron,

Could it be because the loader functions are controlled from the loader valve, not from the Remote Cylinder Operating Lever?

I just tried putting the pressure line into the upper breakaway port, and learned that it is not pressurized. I could try plumbing the return line to the upper port, but I'm reluctant to mess with this system that has worked fine for close to 60 years. It was bought new by the farm across the street. I first operated the tractor about 40 years ago, and bought it about 10 years ago.

I'll revise that part of my question regarding the pressure line to the backhoe. I'm now thinking it will need to be T'ed off the lower breakaway port.

My feeling is that the Dual Hydraulic Remote would be appropriate for operating two independent cylinders, but would not be needed in this case where I don't need to control the cylinders with the Remote Operating Levers. All I need is pressure to and return from two independent gang valves, one on the loader and one on the backhoe.

Thanks for the reply. I know know that only one of the breakaway ports is pressurized.

Joe
 

Since he has a separate dual spool loader valve, the oil is supplied to the valve from the bottom port. Since it is a gear pump with open center hydraulic pressure, the return works better if there is no restrictions. The screw is also out (in? Don't have a manual near by) on the top port, making the tractor hydraulics set for single acting (it just needs pressure flowing to the loader valve in one direction.)
To connect a backhoe in line with the loader valve, your loader control valve would have to have a "power beyond port" (PBY). This is not common. Tractor pressure to Loader valve pressure in, PBY to backhoe valve in, outs on both loader valve and backhoe valve back to reservoir. I'm not sure if the stock tractor pump will have enough flow to sufficiently feed both circuits. One way to find out...

Adrian
 
Do yourself a favor and get a backhoe with a separate pto operated pump.
That 620 will not have very good flow or pressure and plus continues use of the governor mounted hyd. pump will burn up the idler gear bushing.
But for the price of many backhoe attachments you can about find an older tractor loader with backhoe and end up with a stronger more useful unit too.
 
(quoted from post at 20:44:23 08/31/15)
Since he has a separate dual spool loader valve, the oil is supplied to the valve from the bottom port. Since it is a gear pump with open center hydraulic pressure, the return works better if there is no restrictions....

Adrian

Finally getting back to figuring these hydraulics out. Adrian, that all makes sense to me. I have found the illustration below in the Assembly Instructions DIR. No.185-958 for the JD 45 loader that matches exactly what's on my tractor, so it is set up as recommended by Deere.

Mike M., I will heed your PTO pump advice when I get serious about looking for a hoe. I have seen a couple of TLBs in this area in the $3000-$4000 range but they are really rough and I am concerned about finding parts for '60s vintage IH and MF tractors.

I have some more questions about Power Beyond but I will start a new post as this one is complete. Thanks, all, for the replies and info.

Joe

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