Box Blading in Reverse

jinman · Jul 8, 2004

( Hiniker Box Blades use two grader blade edges- one facing forward and one rearward- to smooth and level the surface. )

Norm, what part of this statement leads you to your conclusion? What I read is that they say "...two grader blade edges...." How do you grade with the rear blade if you aren't going in reverse? You and I interpret that statement very differently. /forums/images/graemlins/smirk.gif

Ozarker · Jul 8, 2004

Top N Tilt is irrelevant to this discussion. If you push with the box blade, it is the lower arms that doing the pushing. They aren't designed to push. They are designed to pull. You can push loose material with them but if you try to cut undisturbed soil and hit something solid, you are more likely to bend the lower control arms while pushing than if you hit the same solid object while pulling.

Ozarker · Jul 8, 2004

( When you think about it, at the attach points, there is no difference whether you are moving forward or reverse because the pins are essentially perpendicular to the force. If anything, the pins would have more strength when being pushed on rather than pulled on. /forums/images/graemlins/cool.gif )

There is a big difference. The lower arms are not perpendicular to the force. They are angled out from the tractor. When pulling they will tend to want to pull in toward the center. When pushing they will tend to want to spread apart. They are more likely to bend.

jinman · Jul 8, 2004

( They aren't designed to push. They are designed to pull. )

Ozarker, I don't think you can support the statement that the arms aren't designed to push with any engineering data. Certainly the traditional draft loads have been pulling, but I'll bet you that if we sat down with the engineer who designed lift arms on any modern tractor, he would tell you that pushing in reverse was indeed taken into consideration when sizing the rear lift arms.

Remember, you can always find an exception if you look far enough. If I were to ask you if it's okay to hook a trailer onto the swinging drawbar and back up with it, you'd probably say it was okay. I could then say that if you hit a tree with the trailer while backing you might bend your drawbar. /forums/images/graemlins/shocked.gif

What I'm saying is many older tractors had lift arms that could easily be bent. I think newer tractors are designed by engineers who have full knowledge of the wide range of attachments their tractors will be powering. The boxblade is an ideal example of just such an attachment. /forums/images/graemlins/cool.gif

MicroPilot · Jul 8, 2004

( .... If anything, the pins would have more strengh when being pushed on rather than pulled on. /forums/images/graemlins/cool.gif )

Hmm, What I trying to say was that I would think the attach points would fail before the arms would, at least on my tractor.

_RaT_ · Jul 8, 2004

"When pushing they will tend to want to spread apart."

So, they don't spread apart because they are restrained completely at each end. If the lower link material is put under a stress, inward or outward it would be my conclusion that at some point it would fail at the same load whether it is placed inward or outward and somewhere near the center. The question is at what level of load will that occur. For you it would apparently happen well before the tractor stopped bending your lower links, for me the box would eventually stop forward or rear movement either by spinning the tires or loading the engine. It's what has happened everytime.

The boxscraper is either having the load placed to the outside of the lower link pocket or the inside. The very structure of my 1000lb box completely eliminates the concern were that pressure is placed. Perhaps your tractor is not designed for rear work, thats to bad as it is very effective. Mine is. Why you would suggest that a lower link is more likely to bend outwards then inwards given the same span and potential stress if pressure is applied is beyond me, I can't follow your logic. After cutting several thousand yards of material (in reverse), my conclusion will differ from yours. I would worry far less about the lower arms bending on my tractor as I would where they attach to the tractor. My International could run into a concrete bunker going backwards and never know the difference. It's that beefy. My Kubota while less beefy may not be designed for concrete bunkers, it will handle dirt and the occasional rocks and stumps.

beenthere · Jul 8, 2004

Not that it makes any difference what I think, but I do think Ozarker is right (more right, anyway) and the designed strength of the arms is more in favor of pulling, rather than pushing. There is more risk of bending the arms pushing with them, than there is pulling with them (and there is likely some engineering design built in to support pushing).
Beyond that, the original poster had it right too, that there is a need to be concerned when pushing backwards on a box blade or rear blade. Carefully working backwards shouldn't be a problem.

The 'rear' blade on the box is as much for smoothing going forward as it is for blading backwards, depending on the desires of the operator and the job at hand.

To20Chris · Jul 8, 2004

As I said before, I think it is impact that causes the most damage, and it would be unlikely to have much impact when pushing loose dirt. So in that sense it may be prudent to use the BB in reverse primarily for loose stuff. Since there are no scarifiers in reverse, unless the soil is pretty loose to begin with, then you're not get much of a bite into it anyway, but you would have a beter chance of hitting a rock.

How fast do you guys go with these things anyway? If I hit something imovable my wheels just spin, but the onset of the force is very slow. I don't feel much of a jolt, and I doubt the 3ph arms are stressed much at all. I think the thing to remember is that it you can feel it from the drivers seat, the 3ph arms felt it too.

The forces due to impact are much, much higher than you could achieve just by gently pushing or pulling until the wheels break traction. I would bet that if you go "slow" you cannot break any of the 3ph parts on any of these machines, unless it has a serious defect or design flaw - the traction limited forces won't be high enough to do damage. I would ultimately expect the arms to be weaker in reverse, as they are more in compression than in tension.

_RaT_ · Jul 8, 2004

Maybe what we need are some pictures of our lower links. I'll snap a shot of both my L3830 and Internationqal. If you could get a picture of your Yanmar's lower links it may well squelch just what we are talking about. Mr NoJoyJoyStick, could you get a shot of your NH lower links?

beenthere · Jul 8, 2004

You are right too, and I suspect most damage is when pushing in reverse at 'higher' speeds than at lower speeds. Also, working with the check chains (or supports) improperly adjusted, and even box blades that have the lower pins in non-standard locations.

Many things enter into the equation. Leaves lots of room to 'discuss' things and take stands that lead to heated discussions. Lets be cool. /forums/images/graemlins/cool.gif