Laser grading hydraulic valve issue.

[Complete Turf Care]

I have a laser grading system on an 8' blade that I use to grade athletic fields. As long as I had it on the New Holland TC45 in the pics, it worked fine. But, I bought a Kubota L5740 and on the first grading job with the Kubota, the valve shown in the pics failed. And, that valve cost about $800.

I was told that the reason it failed was because I had hooked up my hoses backwards and applied pressure in the wrong direction. I replaced the valve and went on to the next job. It seemed to work fine, but after about 8 hours of working, I'm starting to notice some oil coming from the $800 valve again. I'm not sure it will fail again, but I know that I can't afford to replace that valve every 10 hours or so.

Does anyone have any suggestions on what may have caused it to fail, and what could I do to prevent another failure? I do know that I did hook the hoses wrong on the first valve, but only applied pressure for a few seconds. I don't think I hooked them wrong for the second valve at all.

Could it have anything to do with the different tractor?

And, someone told me that I needed to add an inline 'backflow preventer' to prevent reverse pressure being applied to the valve.

 

[J_J]

What is the pressure rating of the valve.

Where in the series flow path is the solenoid valve.

Is there a relief valve that would protect it.

Just about every valve will get back pressure at some time, but I am not sure what you mean about back flow if the valve is hooked up correctly.

Is it connected in a series path with a continuous flow to tank, or is it an on/off type valve.

 

[kevin37b]

Is the blade behaving , or jumping around ?sound's like a pressure spike of sorts .

 

[Complete Turf Care]

Thanks for responding JJ. You seem to have the most hydraulic knowledge here. I'll need some help to answer your questions.

What is the pressure rating of the valve. I really don't know. How can I find out?

Where in the series flow path is the solenoid valve.What is the 'series flow path'?

Is there a relief valve that would protect it.I don't know this either. How can I find out?

Just about every valve will get back pressure at some time, but I am not sure what you mean about back flow if the valve is hooked up correctly. The hoses are plugged into one of my remote valves on the tractor. To get pressure, I pull the valve lever and hook a bunge strap to keep it pulled back.

Is it connected in a series path with a continuous flow to tank, or is it an on/off type valve.

I'm don't know what you mean by 'series path'.

Is the blade behaving , or jumping around ?sound's like a pressure spike of sorts .

The blade does not 'jump around'. I can adjust the 'dead zone' on the receiver and I can adjust the response time too. As I get closer to my finished grade, I will reduce both of these adjustments.

 

[J_J]

Pressure rating for the valve would be in the valve description.

If you have a FEL, it has a relief valve, and you might check it for correct settings. If not, then the remote valve has a relief.

You may only have blown out a few o-rings on the old valve and maybe rebuild it.

If you are supplying the laser grader with fluid and you happen to use the 3pt and it builds up pressure to make the relief go off, that pressure will be reflected on any valve up stream including the laser valve. You may/will cause back pressure and interfere with the laser finite controls.

Back pressure will work against the incoming pressure, and damage seals, etc.

You might consider a 3000 psi hyd gage in the system to monitor and trouble shoot the hyd system. Cost about $30

Sample test set.

 

[Complete Turf Care]

Actually, the part that I had to replace is known as a 'proportional coil'. I found the invoice for the one I had to get to replace the original, and the Sauer Danfoss part number is 157B4032. I don't get much info when I google that number.

I'm thinking that I need to add a 'check valve' or 'backflow preventer' or whatever you want to call it to protect the coil.

 

[Complete Turf Care]

Here is a better look at how it's set up on the blade. I found a model number on the valve body of VDN-13973, but I don't get anything on a google search of that number.

You can see the oily area below the 'coil' where this new one is starting to leak. I just want to prevent ruining this one too.

 

[npalen]

Is the valve an open center or closed center type? Are both tractors the same regarding the type? Just curious, don't have any answers.

 

[mrmikey]

This appears to be your setup Danfoss PVG 32 Proportional Valve Components : Neilson Hydraulics, Official Distributors of Bosch Rexroth and Sauer Danfoss , a stackable valve. You decide what you want and more or less mix and match.
Heres your solenoid Search Results : Neilson Hydraulics, Official Distributors of Bosch Rexroth and Sauer Danfoss ..Mike


**EDIT**
I just noticed the solenoid is listed as 24V, is that right, your system 24V?

 

[Complete Turf Care]

Is the valve an open center or closed center type? Are both tractors the same regarding the type? Just curious, don't have any answers.

Both are open center Tractordata.com shows the Kubota at 14.7 gpm and the New Holland at 9.8 gpm.

This appears to be your setup Danfoss PVG 32 Proportional Valve Components : Neilson Hydraulics, Official Distributors of Bosch Rexroth and Sauer Danfoss , a stackable valve. You decide what you want and more or less mix and match.
Heres your solenoid Search Results : Neilson Hydraulics, Official Distributors of Bosch Rexroth and Sauer Danfoss ..Mike


**EDIT**
I just noticed the solenoid is listed as 24V, is that right, your system 24V?

Yes, that does seem to be what I have. But that company is in the UK. My tractor is 12 V as far as I know. It has one 12V battery

 

[mrmikey]

double post...deleted....Mike

 

[mrmikey]

That's the first one I came across.
Here's a link to some good but very deep info re the valve/solenoid http://tinyurl.com/ownk33b , definetly not nightime reading but very informative .
I'm wondering if the solenoid is indeed 24V instead of 12V if it's overheating baking the O rings causing the leak.
(never mind that thought, I see it's 11-32V)

I was told that the reason it failed was because I had hooked up my hoses backwards and applied pressure in the wrong direction

You did notice the 'T' and 'P' on the inlet section?....Mike

 

[Complete Turf Care]

Bump.

J_J, any suggestions on how to protect the 'coil'?

 

[glastron23]

Complete... as far as the coil voltage it's not the problem, your coil is 11-32 volts. If you reversed the pressure/return you more than likely jammed the pressure reduction valve that feeds the pilot valves ( these are on the coil side, the part you replaced) look on page 6 of this link. it's part #2 http://powersolutions.danfoss.com/s...uments/product_literature/11051935.pdf#page=1

 

[J_J]

Voltage or hyd pressure.

There should be o-rings around the solenoid shaft going into the valve. They should be sufficient if there is no hyd spike.

The proportional valve works in relation to the signal it receives, could be large or small increments.

Is there a sensitivity adjustment on the valve or in the laser system.

 

[npalen]

Both are open center Tractordata.com shows the Kubota at 14.7 gpm and the New Holland at 9.8 gpm.



Yes, that does seem to be what I have. But that company is in the UK. My tractor is 12 V as far as I know. It has one 12V battery

Why is it that those doggone Europeans always have to do things wrong. Examples: 220 volts rather than 120 volts for household use---driving on the wrong side of the road etc.
I'm surprised that they don't run their clocks backwards also.

Edit: Just kidding. (ducking and running):laughing::laughing:

 

[oldnslo]

Complete,
Can you check the tank line pressure on the Kubota. Most pilot valves on this type of unit require minimal back pressure on the tank line to function correctly. I would suspect it would be around 25 bar (350 PSI) or less. Excessive tank line pressure will damage the pilot controls. Some valves have the option of an auxiliary drain port just for the pilot section. Not sure if this is an option on your valve though.

 

[ishiboo]

Is the return line on the valve hooked to the "case drain" on the tractor? If it's coming off the loader valve, it probably isn't since there is only one case drain from the loader valve that goes back to the tractor.

Hooked to two sides of the same spool, you could be bleeding a bit of pressure off in neutral via the return OR accidentally activating the loader valve when off in the opposite direction.

The drain side should have NO pressure on it. Disconnect that line off the valve entirely and run it into the oil reservoir on the tractor until you have this figured out, so you don't kill another $$$ valve

 

[aczlan]

The drain side should have NO pressure on it. Disconnect that line off the valve entirely and run it into the oil reservoir on the tractor until you have this figured out, so you don't kill another $$$ valve

This. There are various plugs that will go in your oil fill port (assuming that there is one behind the seat) and let you add a quick connect to drain oil. See how a 3point post pounder is plumbed for some examples.

Aaron Z

 

[ishiboo]

Probably the right way to do this is to change the valve over to an open center, which will have a an "out" and a tank drain. It would then be connected in series with the loader valve.

This is how I operate my post pounder with the open center Kubota.