Proportional Electrohydraulic Systems??

[jgrreed]

Hi Everyone,

Has anyone on here either worked on, or installed, electrohydraulic systems that are proportionally/coil controlled - ie. are 'featherable' (is that a word??).

I've seen a few posts on TBN of electrohydraulic systems that are non-proportional (ie solenoid controlled, 'all or nothing flow'), but not any that are proportional (ie coil controlled, 'sometimes a little flow, sometimes a lot') valves. I see a proportional system as a potential method for adding additional hydraulic controls in a very clean and customizable way.

I've thrown out a few queries on here regarding this, so I hope no one gets upset for asking in too many places......

I really appreciate any help anyone may have to offer.

-Jer.

 

[Wayne County Hose]

Hi Everyone,

Has anyone on here either worked on, or installed, electrohydraulic systems that are proportionally/coil controlled - ie. are 'featherable' (is that a word??).

I've seen a few posts on TBN of electrohydraulic systems that are non-proportional (ie solenoid controlled, 'all or nothing flow'), but not any that are proportional (ie coil controlled, 'sometimes a little flow, sometimes a lot') valves. I see a proportional system as a potential method for adding additional hydraulic controls in a very clean and customizable way.

I've thrown out a few queries on here regarding this, so I hope no one gets upset for asking in too many places......

I really appreciate any help anyone may have to offer.

-Jer.

Okay, what do you want to know. I can tell you that the parts are expensive and sensitive. I worked on forklifts with this system. They used an electric motor to spool the valve. You really need a computer to control the motor. There is either a potentiometer or an encoder on the control handle which sends a signal to the computer. How far you stroke the handle tells the computer how much to move the valve spool. Then, on the other side of the valve spool is another sensor, an LVDT or linear variable differential transformer, to verify the amount of spool movement to the computer. Granted, all systems aren't this complex. In my experience, this is a great system, when it worked. Don't get me wrong, it is a reliable system and I have seen them go over 10,000 hours without a problem, but when they do go bad, you aren't going to Surplus Center for $200.

These are already in use for about 20 years on high end forklifts and have found their way onto more common ones and I think it's a matter of time before you see them on tractors.

Here is where I am used to working on them. http://www.crown.com/usa/products/usa_electric_forklift/turret_trucks/TSP_6000_Series/index.html

You ever seen a forklift like that? Try repairing them.

 

[Farmerford]

WCH:

Are you sure it was a Crown you worked on? It says right on the web site that "service is simplified".

 

[Wayne County Hose]

WCH:

Are you sure it was a Crown you worked on? It says right on the web site that "service is simplified".

That's what they tell the customer. Wait until you get the bill for service. When I left, they were charging over $80 an hour for labor.

 

[kennyd]

Jer,
I know you have asked about this several times now, And I have been thinking of a good response-but I really don't have one, Definitely above my pay grade!

BUT:
I think you will go to the poorhouse and the madhouse trying to design a system like this to "adapt" to your machine. Plus finding the real estate to mount it all will be a problem. Skid steers and Mini excavators use Pilot operated control to keep the light feel on the controls, and those systems a real pricey also-plus the machines are engineered with them in mind so it all works nicely together. I just do not think it's feasible to adapt these sophisticated control systems to a CUT.


There are plenty of great cost-effective and proven solutions to add front and rear remotes to yours or any tractor-with or without dealer/OEM support.

 

[Wayne County Hose]

Jer,

What are you trying to accomplish?

Kenny,
I forgot about that system. I worked on a Takeuchi mini excavator a couple months ago that had a pilot operated valve system, I thought that was real slick. But they did that because of the layout that those minis need to have.

Andy

 

[ccsial]

A hydraulic servo valve will work that way. The more current you put into it the more flow. You can get them bi-directional too, they will work in both directions that way with a plus or minus current.

 

[jgrreed]

Jer,

What are you trying to accomplish?

Andy

My end goals are:

1. Featherable SCV to the front for a grapple that is on a thumb switch on the joystick
2. 2 Featherable SCV's to the rear to control top n' tilt, preferably on a hat switch on the joystick.
3. 1 solenoid on/off valve controlled by a pushbutton (or the trigger) on the joystick that would open the yet to be created PTO driven high flow circuit to drive a FEL mounted snowblower.
4. A simple pushbutton for a horn on the joystick.

I'd like them to be 'slick' - easy to use, and a clean install. I was thinking that the real estate issue might actually be made easier by using an electro system because the valve bank can be anywhere, not limited by plumbing limitations or cable lengths.

I read a bit about the systems that have feedback from the valve/LVDT as a way of error corrrection, but also read about some that don't use that method. What I don't know is whether or not you MUST have a computer of some kind between the control and the valves.

Otto has a TON of options in terms of switches, buttons, hat switches, etc.

I'll look into it more in the new year and let you all know what I find out. I'm gonna try Otto engineering and Scorpion controls. My little bro is an ag engineer, and his girlfriend is an ag engineer who's MSc is in hydraulic stuff. A friend of mine is also an electrician who used to install electro over pneumo and electro over hydraulic systems in a sawmill, so he may be able to help.

Appreciate all your responses, hope we can keep some discussion going on this one.

Happy New Year!!

-Jer.

 

[Wayne County Hose]

Jer,

I think you can do it. It's not going to be easy, but it sounds like you have available to you what it would take to do it. Personally, the more I think about it, I would try to find an old, or wrecked, or burned up mini-excavator and rape all the parts from it. You could do it with a joystick, but now you're talking getting electronics involved. They do use the system I first talked about in freezers down to -20 Fahrenheit and lower so that's not an issue, but I don't know how they would take getting caught in the rain.

Hmmm. You could use a joystick and pilot hydraulics and switch the pilot circuits with solenoid valves.

Andy

 

[6sunset6]

A hydraulic servo valve will work that way. The more current you put into it the more flow. You can get them bi-directional too, they will work in both directions that way with a plus or minus current.

This is probably the simplest way, A potentiometer can increase power to the valve. Your eyes would be the feed back But it does not take much to jam them. With remotes coming on and off the foreign material presence goes up. Anybody here ever see a hydraulic servo get stuck at full open. Even if you had time to turn the pot down , the servo spool is stuck . I saw one once, very scary if it was on a mobile piece of equipment. The one I saw was on a stationary industrial machine ,hydraulic motor running a line shaft with cam actuated motions.
When it ran away it sounded like a machine gun as all the keys sheared off.
I suspect the commercial mobile systems have a lot of fancy protection i.e. $$$$$.