Debating POSITION CONTROL. What is it to YOU?

[boggen]

You are not the first in this thread to respond as such. And I appreciate your take on the situation. But please lets not forget what I said on page one. There are people out there that insist that PC is precisely a self correcting circuit that adjusts for drift. As hard as I have tired to keep this conversation directed to answering this question, "What is PC". People want to bring it back to me being hung up on marketing. I am forced to repeat yet again that this thread is all about what PC is. In spite of a lot of back and forth here, I think, at least in this thread, that we are on our way to establishing that PC has everything to do with being able to stop the travel of the 3pt at some point repeatedly.

With regards to the GC1710, It is my beliefe as it stands right now that the GC can do this, as demonstrated. But I will be getting back to the dealer to have another look at it just to make sure I have dotted the I's and crossed the T's. But it's how we talk about PC that really matters here. Because again, The GC can't be both NON PC and PC at the same time.

then put me on the "depends list", pending on the description that goes with how PC is used. and how it functions.

looking at GC1710 on TractorData.com Massey Ferguson GC1710 backhoe-loader tractor information
and looks what i might more call a SCUT (sub compact utility tractor) and knowing many features of a 3pt may not be there. vs larger tractor. and guessing reason why you are being so nitpickey. "been there done that" and i understand the frustration.

i do not remember if MF has a parts catalog for there tractors on there website or not, it might be worthwhile for you to check.

 

[ovrszd]

Been out in the shop building a hydraulic toplink and waiting for paint to dry so snapped a couple pics to help explain.

The first one is of my Kubota M9540 which has Position Control 3pt and Draft Control. In this picture, the lever to the left is the 3pt lift lever, the lever to the right is the Draft Control. Don't let that confuse you. You can have a tractor with Position Control and not have Draft Control. Since I didn't want to tear the tractor apart and remove the Draft Lever, it's in the picture.

See how the 3pt lift lever can be stopped in any position. When it's moved you feel the drag from the adjustable friction plates that hold it wherever you let go. In this photo I have the position stop block set to carry a brushcutter at the correct height. So if I lift the cutter I move the lever away from the camera or back and let go. The 3pt then lifts the implement to the maximum height and quits lifting. When I want to lower the cutter to the pre-determined height I lower the lever to the block and let go. The 3pt ALWAYS goes to the same height and stops.

It accomplishes this miracle because there is a mechanical linkage that as the arms lift, sends data back to the valve to indicate their position (thus position control). When the arm's location, indicated by this linkage matches the lever location, indicated by where you put the lever, match, the 3pt systems stops lifting or lowering. Clear as mud right??

Here's a picture showing, as best I could, that linkage attached to lift mechanism which is the large splined shaft in the center of the picture. The linkage is the small rod going forward to the control valve of the 3pt.

Now, look at this photo. It's of what John Deere calls 1/4 inch valving. This is the 3pt lever on my JD2210. It's the black lever closest to the seat or to the right and back in the photo. This lever has no guidance as to where it's placed. It actually acts like a rear remote SCD lever. If you gently pull it rearward or forward, nothing happens. you have to move it far enough to activate the valve. Once you do that the lever detents into that position and the 3pt will either lower to the maximum or raise to the maximum. If you want to stop the 3pt in any particular position you have to move it to either lift or lower and then when the 3pt reaches the height you want you click it back to center. After you use it awhile you can get proficient and control the 3pt fairly accurately. But you can never pre-determine a height that you want to work at. Every time you move the implement you have to guess on when to snap the lever back to center to reproduce the pre-determined height. A total PITA if you are using something like a brushcutter.

I'm attaching two photos, first taken with the front of the 2210 at the bottom of the photo, second taken with the front of the 2210 to the right. Also there is no linkage as pictured in the Kubota set. The 3pt arm's location is not known by the lever valve. When they say 1/4 valving they are guessing on your best day you can limit the movement of the 3pt arms 1/4 inch by VERY QUICKLY clicking the lever from the center position to either the lift or lower position and then back to center. Very crude for finish work.......

 

[k0ua]

I can tell you this about Position control on a Long 2360, when the tractor developed an internal leak either in the 3pth cylinder or the control valve. the 3pt arms would drop fast enough you could actually see them dropping, and then you could see the position control feefback raising the 3pt to compensate over and over for the fast leakage. A slow oscillating effect as it were. Also on a Kubota B7500 I used to own, did NOT have Position control, and with a heavy rotary cutter on the back, you would need to make adjustments to the neutral centering valve every 20 minutes or so of mowing as it would "leak down" just a little bit. Not a whole lot, but enough to be annoying. Normally though since you often raise and lower the mower anyway multiple times during that time period and you never get it exactly back in the same place, it just didn't really matter a lot. But there was no exact way to raise the lift and get it to go back to a certain spot.

James K0UA

 

[npalen]

I would think that the "quarter inch valve" would be more useful if there was an position INDICATOR included. This could be in the form of a linkage that would swing a lever in a quadrant much like a position control. A decal on the quadrant would show the current depth of the 3PT.
Depth control on many trail type farm implements is achieved thru what is called a "depth stop valve" which is mounted on the implement or even on the cylinder itself. An adjustable "dog" moves in conjunction with the cylinder and stops the flow when the predetermined depth is reached. An adjustable limit switch would achieve the same thing if used with a solenoid valve.
The 3PT on my Allis 720 simply has a double acting cylinder operated by a directional control valve (DCV) on the dash. I have found this to work well and the capability of down pressure sure makes the 3PT more versatile. Yes, there is a limit to how much down pressue can be applied since traction will eventually be lost. Sure is nice to jack up the back of the tractor to install tire chains etc.

 

[Singalo]

Thanks to all that responded with excellent feed back. I will update again when i have visited the Massey dealer again and get more details.

 

[joshuabardwell]

Singalo: I think one thing you may be misunderstanding is that there is no difference, in the real world, between your theory #2 and #3. All position-control hitches will have a feedback mechanism that tells the hitch whether the correspondence between the control lever and the lift arms is correct. When you lower the lever, the feedback mechanism indicates that the arms need to go down. The arms move down until the feedback mechanism indicates that they are in the correct location for the lever's position. Now, imagine that (your theory #3) "normal drift" occurs, causing the lift arms to drop even though the position control lever has not moved. Again, the feedback mechanism will indicate that the lift arms need to move up, and they will do so. If you have a tractor with leaky hydraulics, you can see this happening in real time. The arms will drop a few inches and then will be bumped back up to the "correct" position.

My point, just to reiterate, is that all three-point mechanisms with position control will correct for "drift" or "leak-down". There is no such thing, in the real world, as your "theory #2", in my opinion.

 

[MasseyWV]

This thread has been quite... entertaining. :laughing:

 

[rockshaft]

Take JJ's advice. Here in the hydraulics forum he is one of the most knowledgeable and helpful members.

I have had both types of control- select and position, should be fairly easy to tell if you sit your rear in the seat and try to move an implement.

By what you describe with the gc, sounds like pc.
Will you be buying a machine this spring? Good luck!
Fyi the last salesman i dealt with didn't know $h1t from shineola about 3ph control!

 

[trktrman]

Been out in the shop building a hydraulic toplink and waiting for paint to dry so snapped a couple pics to help explain.

The first one is of my Kubota M9540 which has Position Control 3pt and Draft Control. In this picture, the lever to the left is the 3pt lift lever, the lever to the right is the Draft Control. Don't let that confuse you. You can have a tractor with Position Control and not have Draft Control. Since I didn't want to tear the tractor apart and remove the Draft Lever, it's in the picture.

See how the 3pt lift lever can be stopped in any position. When it's moved you feel the drag from the adjustable friction plates that hold it wherever you let go. In this photo I have the position stop block set to carry a brushcutter at the correct height. So if I lift the cutter I move the lever away from the camera or back and let go. The 3pt then lifts the implement to the maximum height and quits lifting. When I want to lower the cutter to the pre-determined height I lower the lever to the block and let go. The 3pt ALWAYS goes to the same height and stops.

It accomplishes this miracle because there is a mechanical linkage that as the arms lift, sends data back to the valve to indicate their position (thus position control). When the arm's location, indicated by this linkage matches the lever location, indicated by where you put the lever, match, the 3pt systems stops lifting or lowering. Clear as mud right??

Here's a picture showing, as best I could, that linkage attached to lift mechanism which is the large splined shaft in the center of the picture. The linkage is the small rod going forward to the control valve of the 3pt.

Now, look at this photo. It's of what John Deere calls 1/4 inch valving. This is the 3pt lever on my JD2210. It's the black lever closest to the seat or to the right and back in the photo. This lever has no guidance as to where it's placed. It actually acts like a rear remote SCD lever. If you gently pull it rearward or forward, nothing happens. you have to move it far enough to activate the valve. Once you do that the lever detents into that position and the 3pt will either lower to the maximum or raise to the maximum. If you want to stop the 3pt in any particular position you have to move it to either lift or lower and then when the 3pt reaches the height you want you click it back to center. After you use it awhile you can get proficient and control the 3pt fairly accurately. But you can never pre-determine a height that you want to work at. Every time you move the implement you have to guess on when to snap the lever back to center to reproduce the pre-determined height. A total PITA if you are using something like a brushcutter.

I'm attaching two photos, first taken with the front of the 2210 at the bottom of the photo, second taken with the front of the 2210 to the right. Also there is no linkage as pictured in the Kubota set. The 3pt arm's location is not known by the lever valve. When they say 1/4 valving they are guessing on your best day you can limit the movement of the 3pt arms 1/4 inch by VERY QUICKLY clicking the lever from the center position to either the lift or lower position and then back to center. Very crude for finish work.......

I bet watching that paint dry was more entertaining than some of the posts on this thread!
Your description and photos were informative and right inline with the quote from aaronz. Photos really help people who can't comprehend simple text.
Great Job!

 

[trktrman]

Fyi the last salesman i dealt with didn't know $h1t from shineola about 3ph control!

Tractor salesman are quite often like the typical salesman; they'll try to tell you what you want to hear even if they have no clue what it means....and then you have knowledgeable salesmen who are valuable in many aspects.
I have my BS filter turned up to the max when dealing with many salesmen.