Laser grading hydraulic valve issue.

[aczlan]

Where is the return/OUT hose dumping the laser valve expended fluid?
You should not have much back pressure with the OUT hose going directly to tank.

Looks like its going to the other port on the remote. Running it into the fill port on the back of the tractor should get rid of the backpressure.

Aaron Z

 

[J_J]

Yep, that is what I was alluding to.

 

[Complete Turf Care]

Looks like its going to the other port on the remote. Running it into the fill port on the back of the tractor should get rid of the backpressure.

Aaron Z

It IS going into the other port on the remote. One problem with running it into the fill port, is that that fill cap is vented. I would think that I should keep that vented somehow. And, the threads of that fill cap are different threads from the hydraulic fittings we tried to thread into it.

I have emailed the same video to the guy who sold me the system, and I'm waiting for his reply.

 

[Complete Turf Care]

After talking to the guy who sold me the equipment today, he said that 800 psi back pressure IS enough to cause the coil to fail. So, now I'm going to figure out a way to dump the oil back into the tank without going through any 'Quick Disconnect' fittings. I can go into the oil fill hole, but that cap is vented. How would I vent the tank if I use that hole?

 

[aczlan]

After talking to the guy who sold me the equipment today, he said that 800 psi back pressure IS enough to cause the coil to fail. So, now I'm going to figure out a way to dump the oil back into the tank without going through any 'Quick Disconnect' fittings. I can go into the oil fill hole, but that cap is vented. How would I vent the tank if I use that hole?

I would drill out the cap to fit your hose, then put in a new hole (a small one) to one side for venting.
Alternatively, see some of the ideas posted at: http://www.tractorbynet.com/forums/...ating/98396-post-driver-exhaust-question.html

Aaron Z

 

[Complete Turf Care]

I would drill out the cap to fit your hose, then put in a new hole (a small one) to one side for venting.
Alternatively, see some of the ideas posted at: http://www.tractorbynet.com/forums/...ating/98396-post-driver-exhaust-question.html

Aaron Z

I brought the tractor to a local welding shop yesterday. I showed him the picture with the cap drilled out. We are afraid that the hose will pull out of that plastic cap. Or the cap just won't last in working conditions. He said he may fabricate something with a 1" quick disconnect which should not restrict flow, or allow any back pressure. I'm anxious to see what he comes up with.

 

[J_J]

I would not use QD in a return line.

Use a union. Keep the hose open free from any possible restriction.

 

[Complete Turf Care]

I would not use QD in a return line.

Use a union. Keep the hose open free from any possible restriction.

What exactly do you mean by a 'union'? Can you give a link, or a picture?

 

[J_J]

This is a swivel nut union, and connect two parts together, full open to the flow.

SAE 37° (JIC) Swivel Nut Union

Could also use this to connect two hose together.

http://www.discounthydraulichose.com/product_p/2403lh.htm

If you used a QD on the return line and it became disconnected, you could damage something. A relief valve might help, but why take chances.

Besides, return lines should have low to no back pressure.

It doesn't have to be high pressure fitting.

 

[Complete Turf Care]

I understand now. Thanks JJ.

 

[Complete Turf Care]

Got it back from the machine shop today. It turned out to be very simple, because the oil fill cap was 1" NPT threads. We originally thought it was something different. I will take the male QD off of my 'return' hose and attach it where the red plug on the right side of the pic is.

It will be a few days before I can test it, but now, there should be no restriction of return oil. And, I now have no way to check the pressure.

The guy at the shop is concerned that if my pull pin were to break, there is no QD for that hose to disconnect and severe damage could result.

 

[Industrial Toys]

I find this stuff facinating. Something, I want to get into, except the cost is so high.

I find with hydraulics, just when you think you understand them, you don't.

I think, there is more then one thing going on. Or one thing caused another. Typical!

IF it was ME, the first thing I would do is put everything aside and endeavour to fully understand the differences between the two tractor hydraulic systems.

I still don't understand the differences between open centre and closed centre or talk of "power beyond". I've worked with electric hydraulic valves but never where there is constant flow. I think one needs to fully understand all this to avoid grief!

As for the valve, why wasn't it repairable? Usually the coils are easily removeable as are the internal parts. Just curious, can't you get a 12 Volt coil?

I am curious. When you tried this on the Kubota tractor, with the bunjie cord, did all the other tractor hydraulics work normally?

 

[Complete Turf Care]

As for the valve, why wasn't it repairable? Usually the coils are easily removeable as are the internal parts. Just curious, can't you get a 12 Volt coil?

I am curious. When you tried this on the Kubota tractor, with the bunjie cord, did all the other tractor hydraulics work normally?

The guy who sold me the 'coil' said it is NOT repairable. I was able to find the coil for sale online, but it was in Europe. And, they cost about $700.

And, yes, all the other hydraulics work normally on the Kubota, but I really didn't try to operate the 3 point hitch.

 

[Complete Turf Care]

Got it hooked up today. I put the valve in the line just to verify that there is no more pressure.

Right away, it started spewing oil out of the vent hole in the fill cap. I called my guy at the machine shop, and he will try to fabricate another connection with a diverter welded inside to make sure the return oil goes down, and doesn't spew out of the vent hole.

 

[Complete Turf Care]

Got it hooked up today. I put the valve in the line just to verify that there is no more pressure.

Right away, it started spewing oil out of the vent hole in the fill cap. I called my guy at the machine shop, and he will try to fabricate another connection with a diverter welded inside to make sure the return oil goes down, and doesn't spew out of the vent hole.


View attachment 355997

 

[Industrial Toys]

I'm confused. I would like to understand this. Presumeably, it is an open hydraulic system. So, if you are pouring oil back into the sump at high flow and low pressure, how can your hydraulic system have any pressure left for the other operations?

 

[J_J]

Say what. What are you talking about.

The fluid going to tank is the expended fluid from the grader cyl.

When the cyl are not working, the fluid is flowing from the pump, through all valves, and finally through the grader valve to tank.

The cyls operate is response to the laser beam. If the ground is level and set at zero, no fluid is going through the grader cyl.

 

[Industrial Toys]

So the aux port that he is using is the LAST thing in the loop? And if he had more then one remote, this grader valve and cylinder would have to be in the last spot in the loop, right?

 

[J_J]

He is using the remote valve as the source of fluid for the grader valve, and the OUT flow from the grader valve is going to the filler hole to reduce any back pressure. .

If the remote valve is redirecting all the fluid to the grader valve, the 3pt can not work.

 

[Industrial Toys]

So since the aux valve is bunjied open all the time, the 3ph will never work.

I would love to see a diagram of that grader valve. I don't understand hydraulic schematics, only electronic ones, so that wouldn't mean much to me. But it is deffinitely something I want to pursue someday, the laser thing that is, and I would like to understand it fully before I get there.

Any idea where on the Internet I can go to find out exactly how such a valve works? That $700.00 coil. Is that just one companies part number and marked up price for something you can get cheaper?