Priority Flow Divider Temporary Bypass??

[Iplayfarmer]

Is there a way to temporarily bypass a priority flow divider valve?

Here's the scenario. As discussed briefly over in the "Build it Yourself" forum, my tractor has a 4.8 GPM Hydraulic pump. 1.8 GPM goes to the power steering, and 3 GPM goes to the Loader, 3 pt., etc. I'm adding a Backhoe, and I won't be steering when I'm using the backhoe. Is there a way to modify the system so that when I'm using the backhoe, I can flip a switch or open a valve to get all of the hydraulic fluid flow to the backhoe?

 

[kennyd]

I would suggest a PTO pump...

 

[Iplayfarmer]

I would suggest a PTO pump...

You're cheating.

I already know I can use a PTO pump. I'm just trying to explore this other option a bit. Mostly I'm just trying to understand it a little more.

 

[RickB]

You could put a manual diverter valve in the priority flow connection and divert that flow to a T in the backhoe supply. I can't imagine why that wouldn't work. Shouldn't be too much $$ to find out firsthand.

 

[Iplayfarmer]

You could put a manual diverter valve in the priority flow connection and divert that flow to a T in the backhoe supply. I can't imagine why that wouldn't work. Shouldn't be too much $$ to find out firsthand.

Makes sense. Would I actually need a diverter on both lines? One to send fluid from the power steering and one on the regular circuit to accept the fluid.

 

[kennyd]

I think Rick is thinking to put it just after the pump, before the PD so the whole pump output bypasses the tractor and goes to the BH. If you did this then all the hydraulic functions on the tractor would be inoperative and you would need to make sure the PRV's on the BH valve are set properly to avoid pump damage.

 

[Iplayfarmer]

I think Rick is thinking to put it just after the pump, before the PD so the whole pump output bypasses the tractor and goes to the BH. If you did this then all the hydraulic functions on the tractor would be inoperative and you would need to make sure the PRV's on the BH valve are set properly to avoid pump damage.

I hadn't thought of bypassing the whole thing. It's not a bad idea. Part of the problem there is that I will be using the loader for part of the stability when I'm using the backhoe. Disabling it would be a problem.

The idea has got me thinking, though. Maybe I'll come up with something.

 

[J_J]

I hadn't thought of bypassing the whole thing. It's not a bad idea. Part of the problem there is that I will be using the loader for part of the stability when I'm using the backhoe. Disabling it would be a problem.

The idea has got me thinking, though. Maybe I'll come up with something.

You could use something like this.

Burden Sales Surplus Center Item Detail

 

[RickB]

I think Rick is thinking to put it just after the pump, before the PD so the whole pump output bypasses the tractor and goes to the BH. If you did this then all the hydraulic functions on the tractor would be inoperative and you would need to make sure the PRV's on the BH valve are set properly to avoid pump damage.

Actually, that is not what I was thinking. I proposed diverting the priority flow and combining it with the backhoe supply. Priority flow would be that portion of pump output sent to the power steering system by the priority valve.

 

[quarencia]

RickB, Are you proposing what is in the attached drawing? Most cuts and subs I've seen with Priority Diverters use the output from the power steering to charge the HST. I think cutting flow from the HST, even when you aren't moving, might be bad.

If Iplayfarmer's profile is correct, he has a Massey 1215. I'm not familiar with the flow paths on the 1215. Would want to make sure he doesn't cut fluid supply to the HST though. If his priority flow is ONLY feeding PS, then the diverter idea sounds pretty good.

 

[Iplayfarmer]

RickB, Are you proposing what is in the attached drawing? Most cuts and subs I've seen with Priority Diverters use the output from the power steering to charge the HST. I think cutting flow from the HST, even when you aren't moving, might be bad.

If Iplayfarmer's profile is correct, he has a Massey 1215. I'm not familiar with the flow paths on the 1215. Would want to make sure he doesn't cut fluid supply to the HST though. If his priority flow is ONLY feeding PS, then the diverter idea sounds pretty good.

That's right. I'm talking about my Massey 1215.

You're going to have to explain how the Power Steering would charge the HST. I thought that the HST was a whole separate system from the accessory hydraulics.

Of course there's another crazy idea... Could I guy use the flow from the HST??? What would be the implications of that?

 

[RickB]

If execss flow from steering, or steering return is contributing to the hydrostatic charge, diverting that flow is a terrible idea; do not do it. Don't consider robbing hydro charge flow, the presure is far too low, and your main hydro pump will starve for lube flow as well as drive charge. And robbing hydrostatic drive pressure isn't a good idea for a variety of reasons. The short version is, don't screw around with the hydroststic system.

 

[quarencia]

Don't know that I'm the best to explain it, but I'll give it my non-professional best. Your right in the idea that the HST is a closed loop system with a self contained pump and motor. But there is always some leaking past the HST pump and motor. The oil that leaks out has to be replaced (charged). The HST always has a high and low pressure side. The charge is always injected on the low pressure side of the HST. Because of this it doesn't require a very high pressure to charge the HST. Many small tractors (maybe big ones too for all I know) use the output from the power steering to charge the HST. The Power steering doesn't draw very much head off the flow, except for very short periods when turning the wheels under heavy loads. Because of this there is ample energy left to charge the HST. In the attached diagrams you'll see that my BX2230 puts priority flow through the power steering, then through a pressure relief in front of the filter to maintain high pressure for the PTO clutch, then through another pressure relief in the HST. There is plenty of energy in this flow for charging the HST.

 

[quarencia]

I'm not saying that this is how the Massey 1215 is set up. As I stated earlier, I don't know much about the 1215. The HST on the Massey may be a completely separate system. I'm just saying be very sure that the PS loop does not charge the HST before diverting the flow.

 

[dfkrug]

Most cuts and subs I've seen with Priority Diverters use the output from the power steering to charge the HST. I think cutting flow from the HST, even when you aren't moving, might be bad.

I agree, you should not steal flow from the HST charge pump. That is also
how my B21 was plumbed, as well as my Kioti, and other CUT HST schematics
I studied. I would be curious to know if any CUT HSTs do NOT use the PS
excess flow to charge the HST.

As for stealing flow from the HST to power a hoe? Not practical at all, IMO.
Where would you tap in to? The output from the HST pump is internal to
the HST unit. (Super high pressure, too.)

That said, if you do not have HST, I can not see why a selector between the
flow divider o/p and a tee in the main pump output would not work.

 

[Iplayfarmer]

Thanks for the heads up and warnings about the PS being used to charge the HST. I don't know if that's how it works on my tractor or not; but after the warnings here, I'll be absolutely sure that it's not before I try anything crazy.