PHD Mod from PTO to Hydraulic - need advice

[dsails380]

Like others, I'm tired of manually reversing the auger to get it unstuck. The 3 pt hitch just can't pull it out of the limestone and shale. I'd like to convert to a reversible hydraulic PHD system. The ETA digger and augers barely have 16 hrs on them, so I'm reluctant to part with them.
Tractor information: M-F GC 2410 TLB. Open center hydraulics. 4.3 GPM at rear remote. 1900 psi relief valve setting. 18.7 hp @ 555 rpm rear PTO. There are 3 hoses at the rear remote pump supply, pump return, and direct return to sump.
1.) Determine which hydraulic motor to use for low speed, high torque. 18.7 hp rear PTO =177 ft-lb torque, or 2123 in-lb torque. Surplus Center calculator indicates at 1900 psi system pressure, and a hydraulic motor displacement of 7.2 in3, maximum hydraulic motor torque will be 2178 in-lbs. With flow of 4.3 GPM and 7.2 in3 displacement, max motor speed will be 138 RPM. Dynamic BMPH125H2KP (Surplus Center) looks like the perfect combination of torque and speed, and is reversible. Am I missing anything here? Should I be looking at another, more suitable motor?
2.) Determine which Spool Valve to use. I've selected a 1 spool, 8 gpm, Prince MB11B5C1 (Surplus Center) that comes set up for open center hydraulics and bi-directional flow, for that all important reverse auger rotation. The integral relief valve comes preset at 2000 psi. Will there be a problem with overpressure of the components from this valve back to the tractor pump? Or will the tractor 1900 psi relief open first? Would a hydraulics expert select this valve for this application, or is there one better suited?
3.) How to plumb the system hydraulics? Looking at the Prince MB11B5C1 schematic, I can see that I connect the tractor pump supply hose to port "P"? I would not install the high pressure carryover plug because I want the open center hydraulics to work, and I don't need power beyond. I also see that I would connect the tractor pump return line to port "C"? Ports A1 and B1 would be connected to the Dynamic hydraulic motor ports. Now the tough question Should I connect the tractor direct return to sump hose to port "T"? I don't know enough about tractor hydraulics, so I'm again looking for an expert's opinion before I go off and do something stupid and regrettable.

 

[J_J]

What psi is your pump rated?

You should mount the new valve as a remote and feed it from the PB from the FEL, or if one of the hoses to the back is PB fluid then that goes to the IN port of the new valve.

The return/tank port from the valve should go to tank, and the PB adapted port of the remote should go to the 3pt, so you will have lift.

 

[dsails380]

"What psi is your pump rated?" I checked the operators manual, and there's no pump rating. the only information I have to go by is the relief valve setting. I think I see where you're going with this. Every pump has a flow/pressure curve. I'll ask M-F and report back.

"You should mount the new valve as a remote and feed it from the PB from the FEL, or if one of the hoses to the back is PB fluid then that goes to the IN port of the new valve."

"The return/tank port from the valve should go to tank, and the PB adapted port of the remote should go to the 3pt, so you will have lift."

Yes, I agree. I'll mount the remote valve at the back of the tractor, similar to the TnT setups I've see on TBN.
I have 3 hoses at the rear of the tractor for the backhoe:
I have a PB hose called "pump supply" in the operation manual.
I have a PB return hose called "pump return" in the operation manual.
Lastly, there's a third backhoe hose for the "direct return to the sump" in the operation manual.
When the backhoe isn't installed, the "pump supply" and "pump return" hoses are connected together. The "direct return to sump" hose is just capped.

So, it sounds like the "pump supply" hose feeds the remote valve. The "pump return" hose must be connected to the return side of the valve to operate the 3 pt hitch, and the "direct return to sump" hose must be connected to the return side of the valve too. Please correct me if I'm wrong.

Thanks for the quick reply JJ.
Dave Kay

 

[dsails380]

I've attached a schematic of the Prince valve. I assume P=PB supply, C=PB return, and T=direct return to tank.

 

[J_J]

Is there a valve for your auger?

Are you using the remote valve to control the auger?

If you are installing remotes, you might consider installing a three spool valve at the back for possible T-N-T, and use the third spool for the auger.

The third spool might also be a detent spool for continuous operation.

I would also install QD's on all the work ports. and on the Auger hoses. Put a QD on the tank hose from the tractor. Put QD's on all hoses from the auger. When you unplug the auger, the QD keep you from losing any fluid.

You just plug the first and second work ports until you have the T-N-T installed.

If the new valve is set to 2000 psi, and the FEL valve is set to 1800, then the FEL relief will always operate first.

If you get a different valve, set all relief to the same value.

 

[dsails380]

Is there a valve for your auger? Not yet, but the Prince valve will be for auger control once I install it.

Are you using the remote valve to control the auger?

DK: Yes, I will be using the Prince valve for fwd and reverse operation.

If you are installing remotes, you might consider installing a three spool valve at the back for possible T-N-T, and use the third spool for the auger.

DK: You bring up a good point. If I install the 3 valve spool now, it will be easy to convert the 3pt to T-N-T later.


The third spool might also be a detent spool for continuous operation.

DK: What is a detent spool? What would it be used for?

I would also install QD's on all the work ports. and on the Auger hoses. Put a QD on the tank hose from the tractor. Put QD's on all hoses from the auger. When you unplug the auger, the QD keep you from losing any fluid.

DK: Yes, I plan to put QDs on the auger hoses. Actually, if I install a 3 valve spool, I'd connect the existing backhoe hoses to the 3 valve spool without QDs. I'd then run 3 new hoses from the 3 valve spool for the backhoe - PB supply, PB return, and direct return to sump.

You just plug the first and second work ports until you have the T-N-T installed.

DK: Okay - sounds good.

If the new valve is set to 2000 psi, and the FEL valve is set to 1800, then the FEL relief will always operate first.

DK: Good - thanks.

If you get a different valve, set all relief to the same value.

DK: Okay, I'll need to buy a liquid filled gauge then.

DK: BTW - I sent an email to M-F last night requesting a tractor pump pressure/flow curve, or at least a pump pressure at 4.3 GPM if a curve isn't available. They're usually prompt, so I'd expect to hear from them early next week. Thanks again for your help JJ.

Dave K.

 

[J_J]

Here is an example of two 3000 psi hyd test set. Just match up QD's for your QD's. They are liquid filled.

You could also mount a hyd gage in a tee going into the FEL IN port, and use it to monitor your hyd system.

These test sets were made by some of our TBN members.

 

[dsails380]

Hi JJ. A gauge will certainly help me determine actual hydraulic pressure at the rear remote hoses. It would also be useful for trouble shooting. I favor a tee setup. I'll see what I can pickup locally. I have a couple QD bodys, all I need is a QD stem, 1/4 Tee, and a liquid filled gauge - I'm thinking 0-3000 psi. I'll post back when I find out what the rear remote pressure is.

Thanks again for your help. :thumbsup:
Dave K.

 

[dsails380]

Got the remaining hydraulic test gauge parts today, and tried it this evening by installing it between the backhoe rear remote QCs. No pressure until I raised the 3pt and caused it to dead head, at which point it read 1800 psi, and sounded like the relief opened.

I asked AGCO Answers for a pump flow/pressure curve, and they referred me to the dealer. My dealer suggested a flow test at the rear remotes so the PHD hydraulic motor could be properly sized, and warned that improper motor size could cause the fluid to heat up and damage the tractor.

Could someone please explain this to me? I understand that when you compress a fluid, you add heat. I'd expect fluid coming from the pump to be warm, but as the fluid leaves the motor, I'd expect it to loose some heat through expansion, however minimal. I'm not a hydraulics expert, and would sincerely like to understand this.

Thanks,
Dave K.

Here's a pic of my test gauge setup.

 

[DJNebraska]

Could someone please explain this to me? I understand that when you compress a fluid, you add heat. I'd expect fluid coming from the pump to be warm, but as the fluid leaves the motor, I'd expect it to loose some heat through expansion, however minimal. I'm not a hydraulics expert, and would sincerely like to understand this.

Hydraulic oil is not very compressible. Especially at only 1800 PSI. You'll have way less than 1% compression of the fluid.

Very little heat is generated by the pump. The hydraulic motor will heat the system more. Hydraulic motors have efficiency percentages. As a general rule for geroler or duroler motors, use 75%-80%. Spur gear motors will be a little more efficient, around 85%-90%. I'm assuming you have a geroler or duroler motor.

So, if you're providing 4.3 GPM at 1800 PSI to the motor, you are theoretically sending 4.5 horsepower to the motor. You lose the approximately 20% at the motor. That energy is turned into heat (0.9 horsepower of heat generation).

Heat is also generated by restrictions in the system (couplers, hoses, adapters). All of these components have what is referred to as "pressure drop." Pressure drop creates heat as well.

I hope this helps!