Laser grading hydraulic valve issue.

[J_J]

Superior Instrument - CT's Source for Sales and Service of Construction Lasers, Machine Control and Surveying Instruments

PT HYDRAULIC VALVE PKG


This hydraulic system utilizes digital-proportional valve bodies for greater accuracy and reliability than other systems on the market.

 

[Complete Turf Care]

I wanted to buy my system from this guy last year, but he had shut down for 3 months because of an injury. His web site used to show the same blade I have. It looks like he has downsized a lot in the past year.

Laser Grade Company

 

[Industrial Toys]

My God! I checked around for information. Such a system costs $20,0000 and I don't believe that even covers the laser and tripod!

And yet the sites don't give you any precious information. I'm still just as stupid when it comes to proportional valves. I went on that above site, before you posted it and was rather disappointed. Looks like more of a site to sell a plastic dog dish then a $20,000.00 system!

My very first thought when I first encountered this thread was "HEAT". Apparently it is an issue and your particular manufacturer speak of manifolds for open centre systems, but in such cryptic language that I still don't know what is what.

I hope you have your problem on the way to be sorted out, but my gut feeling says no. By the way,what is that bright colored protrusion mounted on the valve body on the opposite side of the servo valve?

 

[Complete Turf Care]

By the way,what is that bright colored protrusion mounted on the valve body on the opposite side of the servo valve?

That is to manually operate the hydraulic cylinder

 

[oldnslo]

My God! I checked around for information. Such a system costs $20,0000 and I don't believe that even covers the laser and tripod!

And yet the sites don't give you any precious information. I'm still just as stupid when it comes to proportional valves. I went on that above site, before you posted it and was rather disappointed. Looks like more of a site to sell a plastic dog dish then a $20,000.00 system!

My very first thought when I first encountered this thread was "HEAT". Apparently it is an issue and your particular manufacturer speak of manifolds for open centre systems, but in such cryptic language that I still don't know what is what.

I hope you have your problem on the way to be sorted out, but my gut feeling says no. By the way,what is that bright colored protrusion mounted on the valve body on the opposite side of the servo valve?

Industrial,
a) A simple fact in hydraulics is that proportional valves create heat by design. The way a proportional valve works is the control flow via pressure drop. Pressure drop equals heat generation.

b) Depending on the style of proportional valve the coils may not be sold as seperate item since they are "tuned in" at the factory. This is nothing new or revolutionary in the proportional class of valves.

c) I am not surprised the webiste does not provide detailed operating information or schematics. This is a semi proprietary system with it's own slight variation on how it functions.

d) Open center systems: These have a fixed displacement pump which produces oil flow flow when ever the pump is turning. This flow must be directed some where at low pressure (open to tanK) or the system will over heat quickly if allowed to dump across the relief valve.

e) Closed center systems: These use variable volume pumps and the flow can be blocked (closed from tanK) with very little heat generation.

 

[Industrial Toys]

Thanks for the information. I didn't expect detailed information, but something a little better then what they had. But then I've seen that all these systems mostly talk about all the neat stuff you can do, but never speak of the hardware itself.

What makes these things so expensive? I have so many questions about these systems, I should start a thread rather then hijack this one. For one, I am curious is there is a position sensor on the cylinder? Most computer controlled systems like a CNC machine has a feedback loop indicating position or speed.

 

[aczlan]

Thanks for the information. I didn't expect detailed information, but something a little better then what they had. But then I've seen that all these systems mostly talk about all the neat stuff you can do, but never speak of the hardware itself.
What makes these things so expensive? I have so many questions about these systems, I should start a thread rather then hijack this one. For one, I am curious is there is a position sensor on the cylinder? Most computer controlled systems like a CNC machine has a feedback loop indicating position or speed.

No feedback on the cylinder, it uses the laser detector on the "stick" to tell where the blade is in relation to the ground and to know how far up/down it needs to go.

Aaron Z

 

[Industrial Toys]

Thanks again. Just two more questions and I won't have to start a thread.

How wide an area does the stick "see" and what happens if you loose the laser as in going too high or too low? Do you have to basicallly be within grade to a certain extent before you can employ the laser grading?

Q # 2 I see many systems with two receivers on each side of a blade. Is that just like having two seperate systems?

 

[aczlan]

Thanks again. Just two more questions and I won't have to start a thread.

How wide an area does the stick "see" and what happens if you loose the laser as in going too high or too low? Do you have to basicallly be within grade to a certain extent before you can employ the laser grading?

Q # 2 I see many systems with two receivers on each side of a blade. Is that just like having two seperate systems?

A1: It depends on the stick and how many receptors were put on it. Wider range = more expensive.
A2: That allows the system to grade a slope (ie: make the crown of a road while driving down it) and they will generally be hooked up to tilt the blade from side to side.

Aaron Z

 

[oldnslo]

Not sure if the technology has improved but Spectra Physics used to guarantee 1/4 inch accuracy over 1,000 ft. This was 20 years ago so technology has probably improved this accuracy.

 

[Industrial Toys]

I am curious if this matter was ever sucessfully resolved?

 

[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

I am curious if this matter was ever sucessfully resolved?

No, it has not. My guy at the machine shop is supposed to be fabricating a fitting similar to the one in my pic above, but with a 'baffle' welded in it to keep the oil from spewing out of the vent hole. He hasn't got that for me yet.

 

[J_J]

Is the return pipe below the fluid level.

Dumping into the air space in a reservoir is not recommend for any hyd system.

Is your reservoir at the correct level with all cyl filled?

 

[Complete Turf Care]

Is the return pipe below the fluid level.

Dumping into the air space in a reservoir is not recommend for any hyd system.

No it's not below the fluid level. It dumps into the fill cap. If what you are saying is true, then I'll have to start over. I don't want to start over.

 

[J_J]

Why start over, any return line should be returned below the fluid level, just extend the line going further down into the fluid.

 

[aczlan]

Why start over, any return line should be returned below the fluid level, just extend the line going further down into the fluid.

The trick will be doing that inside the tee while leaving the vent intact...
To test, you might cap off the vent and loosen the dipstick.

Aaron Z

 

[Complete Turf Care]

I had a new fitting made hoping to direct the oil flow downward so that it wouldn't spew out of the vent. You can see the new fitting on the left and the old one on the right.
It didn't work. As soon as I got the rpm's up on the tractor, oil began spewing from the vent.



The picture below shows the vented cap in place with the dipstick where it should be.


I replaced the vented cap with a non-vented cap and pulled the dipstick out just a little hoping that this would be enough to 'vent' the system. I'm headed to work on a field early next week with it like this. Hope it works.



I also checked with my Kubota dealer to see if there is any kind of 'power beyond' kit available for this tractor, and they said there is not. I would have to go to an aftermarket system. I've gotten so many different stories about how I should handle this, that my head is spinning. I'm going to try it like this, and if this doesn't work, I'll hook it back to my New Holland tractor to finish this job.

 

[jenkinsph]

I suspect that set up above will entrain so much air to cause system damage. Not familiar with Kubota plumbing but it would seem to be better to tee into the lower drain plug than to go thru the vent/fill.


Hope you can get this resolved and put all of this to work.:thumbsup: I am waiting on a PVG 32 dual valve set up for a new laser system in the making right now.

 

[Complete Turf Care]

What sort of damage to the system would it cause?

How would I know if there is too much air in the system?

 

[jenkinsph]

I would be concerned with pump cavitation and heat. When you compress the hydraulic oil with air bubbles in it you can get a lot of heat generated, clear oil without the bubbles isn't going to compress/expand much.

I would watch carefully for the pump over heating, might wan't to buy an infrared thermometer. Does your tractor have a transmission temperature gauge? If so that should provide you with some indication of rising fluid temperatures.



Glad I found this thread as it is difficult to find much information on machine control systems for the small tractors. It is easy to see that a tractor with closed center hydraulics is a much better choice, might wan't to look for an older Deere 2wd tricycle 3020. That might be a lot better choice than my current 4520 for this work as I need the 4x4 engaged to pull the box blade and it it has open center hydraulics.

The gentleman who has Laser Grade did suffer a bad injury that is causing him to shut down his business. He was the most helpful person I have found on machine control systems on the internet. I have spoken to his wife early last year and hope for the best for Dan and his family.