Adding selective control valve to John Deere 750

[Moondoggy]

I recently acquired the power angle blade made for my John Deere 750. I need to add the selective control valve and was hoping to get some advice. I found the original 2 handle control valve new for $1180.00, plus shipping of course. I would really prefer a single joystick type control. The valve must have a float position. The 750 is Open center hydraulics, constant flow, 2030 psi. It looks by the service manual it must have power beyond. Any recommendations for what may be a good fit for this tractor and any other random advice would be appreciated.

 

[jd4310man]

I had a very similar problem with my 655. I built a front blade and needed to add a hydraulic valve to control it. My tractor didnt come with the dual selective control valve so I added an aftermarket one that has power beyond capability. The tractor comes standard with a flow divider to power the steering and rockshaft functions. I removed the factory metal line from the pump and had a new hose made to feed the new valve first and then another line to power up the factory flow divider from the power beyond port thus powering up the whole system. Here is a valve that would work 2 SPOOL COMPACT 1 GPM JOYSTICK CONTROL VALVE | Directional Control Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com Hope this helps

 

[Moondoggy]

I had a very similar problem with my 655. I built a front blade and needed to add a hydraulic valve to control it. My tractor didnt come with the dual selective control valve so I added an aftermarket one that has power beyond capability. The tractor comes standard with a flow divider to power the steering and rockshaft functions. I removed the factory metal line from the pump and had a new hose made to feed the new valve first and then another line to power up the factory flow divider from the power beyond port thus powering up the whole system. Here is a valve that would work 2 SPOOL COMPACT 1 GPM JOYSTICK CONTROL VALVE | Directional Control Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com Hope this helps

Thanks jd4310man. That looks like a good fit. Saved me some time searching.

 

[jd4310man]

Here is a few pics of the valve and hoses on the 655

 

[oldnslo]

Normally steering gets priority in a circuit for safety reasons.
Where is the relief valve in this circuit?

 

[CalG]

As of yet, I have not been able to justify the "steering first| safety angle.
I'm trying to imagine being in a situation when Steering is the important function, and the operator is unwilling (or unable) to let go of the bucket or boom control handle. In fact, when things get screwy, I want the bucket DOWN first, then I can deal with the angle of the front wheels.

Perhaps you can offer a situation that I have not considered. But I've got no issues with hard turning while lifting or scooping.


Doesn't the tractor internal system contain an over pressure relief that covers the entire system including any PB extension? I made a post asking the same not long ago. Seems that any PB relief valve is redundant. But???? Are there exceptions?

 

[jd4310man]

Usually each valve has a relief valve that can be set to a specific pressure for the job at hand.

 

[CalG]

Usually each valve has a relief valve that can be set to a specific pressure for the job at hand.

But only the lowest pressure setting is available to the system. All higher settings become invalid. So if the loader valve relief is set to 2ksi, that is all the 3pt will ever see. And lift capacity will follow.

 

[oldnslo]

As of yet, I have not been able to justify the "steering first| safety angle.
I'm trying to imagine being in a situation when Steering is the important function, and the operator is unwilling (or unable) to let go of the bucket or boom control handle. In fact, when things get screwy, I want the bucket DOWN first, then I can deal with the angle of the front wheels.

Perhaps you can offer a situation that I have not considered. But I've got no issues with hard turning while lifting or scooping.

Some possible concerns depending on the valve style:

Regenerative tilt circuit: No flow is going to the power beyond circuit while using regenerative dump. common SCUT's

lift or lower at full speed: no flow to the power beyond circuit.

Blade tilt: again full speed no flow to the steering circuit.

I know on my previous Kubota BX and now on my Branson I perform all of these operations while driving and not having steering would be a problem for me.

Connecting into the line between the flow divider and the current directional control valve provides steering and functions. Granted the auxiliary functions will operate slower since part of the flow is going to steering.

 

[kthompson]

What type of steering systems do these tractors use? Is the hyd a power steering system supporting a full linkage system or a hyd steering system
with no linkage, no hyd pressure no steering ability?