Rear Blade Blade not high enough

[Ken45101]

MtnViewRanch: That is a serious backblade!!! very nice setup. i was wondering about the hydraulics on there.. i know right now.. when i tilt my blade for say ditching.. its tough to cut through the ground.. just seems like an amazing amount of force pushing back against the hydrauilics. what would it take to blow out either the cylinder or maybe a line.. something like that.. on there? has it ever happend?

There is no downforce on the 3pt other than the gravity of the implement itself. It will ride up and down as it wants. Once your implement is on the ground, it doesn't matter if you push the lever further or not, there is no additional force and, if need be, the implement will ride up without loading the hydraulics.

Now I guess it's possible to get into a situation where the toplink is extended and the upforce hits the mechanical limits of the 3pt (like backing into a hillside or berm). In that case, if anything is damaged, it's probably going to be that the top link gets bent.

Ken

 

[Gordon Gould]

Gordon, any chance of a picture or two. How I'm understanding your configuration is that the bottom of your side links actually would be pointing towards your tractor instead of away from it. So when you have your side links set to the outer most hole they are vertical and the bottom does not slope away from the tractor? Is there a chance that your lower lift arms are on backwards? The holes that you connect to your implements should be attached at the tractor and the ones at the tractor should be the ones that are connected to the implement. I think that if your arms were to be turned around your tractor would be like the rest of ours are. To quote my wife, "Dude! They put your tractor together wrong!" Notice in the pics that the side links slope away from the tractor at the bottom.

OK here are my pictures. Both have the lift control in the full up position.
I took the first with both side links in the far holes. My normal position. Then I move the left side link to the closest hole. You can see the height gained. And if you follow the two arm angles out another 4' to where the blade would be, I think even you would agree that the blade would be signiicantly higher (feet) with the side links close. This would include the normal roll back from the top link.
Kubota Knows how to design things. This is a very flexable 3ph.
Like I said I would not lie to you guys.

gg

 

[wvpolekat]

OK here are my pictures. Both have the lift control in the full up position.
I took the first with both side links in the far holes. My normal position. Then I move the left side link to the closest hole. You can see the height gained. And if you follow the two arm angles out another 4' to where the blade would be, I think even you would agree that the blade would be signiicantly higher (feet) with the side links close. Not including the increased roll back from the top link.
Kubota Knows how to design things. This is a very flexable 3ph.
Like I said I would not lie to you guys.

gg

You made my day. I kept trying to think though this in my head to figure out if I should move mine in to get the blade higher. Now I know I can. Once my son goes down for his nap, I will go check it out. Will take some pictures of the difference in blade height.

 

[wvpolekat]

Yes, but not a worry for a rear blade unless it weighs an awful lot.

I understand that, but when making a change like this, people should be aware of it since they may put other implements on it.

 

[Ken45101]

FWIW, I have similar problems with my M5040 and a 6' Woods medium duty scraper blade.

It seems to me that the geometry is wrong, as I lift the blade, the bottom tilts more forward. As I drop the blade, the bottom moves to the rear. In effect, the blade is rotating rather than just moving up and down. If I don't have things adjusted just right, the 3pt will go very low with the blade tilted way down in front.

On uneven slightly uneven ground, the blade may hit in the up position...or not touch the ground in the down position. I don't have problems with the box blade.

I suspect that the vertical difference between the top and lower hitch points is a lot shorter than the vertical difference on the tractor end of the 3pt.

I now have a hydraulic top link which helps some but it's still not right.

Ken

 

[wvpolekat]

Ok, just got back from the garage.

I forgot the camera, but did measure.

With lift links in the hole furthest from the tractor and top link in the top hole on tractor: 9" from blade to ground

With lift links in the hole closest to the tractor and top link in the top hole on tractor: 8" from blade to ground

With lift links in the hole furthest from the tractor and top link in the bottom hole on tractor: 11" from blade to ground.

Hard to argue with your pictures, as they clearly show the arms lifting higher when the lift arms are moved closer to the tractor. But, in my testing, I got the opposite result. Possible it is because I was measuring implement height?

 

[jlsmith]

OK here are my pictures. Both have the lift control in the full up position.
I took the first with both side links in the far holes. My normal position. Then I move the left side link to the closest hole. You can see the height gained. And if you follow the two arm angles out another 4' to where the blade would be, I think even you would agree that the blade would be signiicantly higher (feet) with the side links close. Not including the increased roll back from the top link.
Kubota Knows how to design things. This is a very flexable 3ph.
Like I said I would not lie to you guys.

gg

Ok i see what your saying I didnt think you would lie to us. Question if you was to take the right lift arm and move the to hole #3 wouldnt that give the same hight and more stability on the lift arm itself. Just asking .:thumbsup:

 

[rjkobbeman]

Ok, just got back from the garage.

I forgot the camera, but did measure.

With lift links in the hole furthest from the tractor and top link in the top hole on tractor: 9" from blade to ground

With lift links in the hole closest to the tractor and top link in the top hole on tractor: 8" from blade to ground

With lift links in the hole furthest from the tractor and top link in the bottom hole on tractor: 11" from blade to ground.

Hard to argue with your pictures, as they clearly show the arms lifting higher when the lift arms are moved closer to the tractor. But, in my testing, I got the opposite result. Possible it is because I was measuring implement height?

The test you left out is the links in the hole closest to the tractor and the top link in the bottom hole.

Having your links in the hole closest to the tractor will raise (and lower) your lift arms more. However there is some complex geometry going on with the 3ph -- the length of the top link AND its mounting point on the tractor have a profound affect on the lift height (or lack therof) of the rear and angle of the implement. (Lift height in the front is always related to the lift arm.)

Depending on the mouting point of your TL and the legnth of your TL, you can actually "over center" (for lack of knowlege of the real term in this case) when lifting you implement and cause the rear to dip back down. This was a problem with my cutter. Until I started using the bottom hole I could not get the tail wheel more than a couple of inches off of the ground. (Of course if I shortened the TL screw jack I could fix it... but that was a lot of work.) I now have a HTL so the problem is moot.

 

[wvpolekat]

I will do that one next time I am out there. Actually broke the cotter pin on one side, so I have to tinker with it anyhow.

I was amazed how much difference moving the top link had. It is a much more complex setup than you realize at first.

 

[MtnViewRanch]

Gordon, thanks so very much for posting theses pictures,:thumbsup: like they say,"a picture is worth a thousand words" Pictures sure help to clarify things.
I have looked at 100's of tractors and have to say that I have never noticed any that had a set of lift holes so close to the pivot point. I am curious as to how much the lifting capacity is diminished with the side links attached at that closest hole.

Anyway, thanks again for putting me straight.

 

[Ken45101]

I am curious as to how much the lifting capacity is diminished with the side links attached at that closest hole.

It probably specifies that in the manual, I know mine does. Check in the specifications section where it gives the lift specs.

Ken

 

[MtnViewRanch]

It probably specifies that in the manual, I know mine does. Check in the specifications section where it gives the lift specs.

Ken

Ken, are you telling me to look at the specs? :confused2:

 

[ole farmerbuck]

Anyone know why i'm not getting any email notices about this thread i started? I think i have everything set right. (but then again, i had my 3point set wrong!)

 

[Gordon Gould]

Gordon, thanks so very much for posting theses pictures,:thumbsup: like they say,"a picture is worth a thousand words" Pictures sure help to clarify things.
I have looked at 100's of tractors and have to say that I have never noticed any that had a set of lift holes so close to the pivot point. I am curious as to how much the lifting capacity is diminished with the side links attached at that closest hole.
Anyway, thanks again for putting me straight.

With the side links in the far holes, which are 12" from the pivot point, I have 2870 lbs of lift at the arm lift points. If the side links are in the close holes, which are 6" from the pivot point, I get 1435 lbs of lift at the arm lift points. Still plenty for any blade I could put on my tractor which is in the 30 hp class.

 

[JoeL4330]

FWIW, I have similar problems with my M5040 and a 6' Woods medium duty scraper blade.

It seems to me that the geometry is wrong, as I lift the blade, the bottom tilts more forward. As I drop the blade, the bottom moves to the rear. In effect, the blade is rotating rather than just moving up and down. If I don't have things adjusted just right, the 3pt will go very low with the blade tilted way down in front.

On uneven slightly uneven ground, the blade may hit in the up position...or not touch the ground in the down position. I don't have problems with the box blade.

I suspect that the vertical difference between the top and lower hitch points is a lot shorter than the vertical difference on the tractor end of the 3pt.

I now have a hydraulic top link which helps some but it's still not right.

Ken

The geometry is tricky, but you should be able to correct "angle of attack" of the blade with your hydraulic top link ...if you can't get enough range of motion, consider using a "swinging top link" ...I do, because I also have a hydraulic tail wheel that I can adjust and found that it otherwise fights my top link ...here is a picture of the link I insert between the top link and the implement ...it is the often discussed Harbor Freight link.

These two pics should help explain and show the geometry

 

[Ken45101]

Yes, basically I have to use the hydraulic top link to get decent travel height for the scraper blade.

My rotary cutter has a moving frame for the toplink, so that works well. I ought to look at the mount dimension on the cutter (and box blade) vs. the scraper and see if the scraper has incorrect mount geometry.

I wonder if it has to do with the tractor being cat 1/2 and probably more vertical spacing between the lower arms and the toplink attach point. My scraper blade is supposed to be cat 1/2, but maybe it's not really deigned properly for cat 2?

Ken

 

[MtnViewRanch]

I think that not enough lift for rear blades & landscape rakes is a very common problem. If you think about it, you have the hitch and that whole thing has to be above the rear blade so that it can turn 360*. So the hitch is a bit higher to start with just so that the implement can be adjusted properly. So depending on how one has their 3pt linkage adjusted can make a pretty big difference on how much ground clearance one has with their blade or rake.

 

[Ken45101]

I think that not enough lift for rear blades & landscape rakes is a very common problem. If you think about it, you have the hitch and that whole thing has to be above the rear blade so that it can turn 360*. So the hitch is a bit higher to start with just so that the implement can be adjusted properly. So depending on how one has their 3pt linkage adjusted can make a pretty big difference on how much ground clearance one has with their blade or rake.

OH! I think you may have hit an important point there! Good thinking.:thumbsup:

Ken

 

[ole farmerbuck]

I had my dealer adjust the linkage the other day for the the 3 pt. Seems to make things a lot better.

 

[Baby Grand]

I will do that one next time I am out there. Actually broke the cotter pin on one side, so I have to tinker with it anyhow.

I was amazed how much difference moving the top link had. It is a much more complex setup than you realize at first.

It is a complex as well as an amazingly flexible design, in that you can get all kind of different motions by simply changing the length of a link. Thank you, Harry Ferguson! The 3pt hitch is actually a 4 bar linkage:

Four-bar linkage - Wikipedia, the free encyclopedia

Here's a little animation that you can adjust - a very handy tool for doing some down & dirty design work:

Flash Animation of Four Bar Mechanism

Who says engineering isn't cool?
Well, after all the boring classes, it's cool ... kinda ...