tree pusher

[Sam in WA]

Does anyone use a tree pusher on a larger Cat dozer (D7-D8 size)? I have built tree pushers, but have had problems with bending when large enough trees are encountered. We usually use 4 and 6 inch heavy wall square tubing for the frames and braces. the pusher mounts to the top of the standard dozer blade and we have modified our root rakes to fit with the tree pushers installed. Does anyone have any suggestions on how to prevent the bending? Any help is much appreciated.

 

[Anonymous-0]

Heavier wall tubing and heavy gusseting. If it's bending, it's not designed or built strong enough. Try to use shorter lengths of tubing with some more corners rather than using longer straight pieces of tubing. The corners will add strength and can be gusseted which will give even more strength. You could put internal stiffeners in the tubing but this would have to be done before the assembly is welded up. Some slots could be cut length wise in the tubing to attach the stiffeners and then the slots could be completely welded up like a plug weld. Additional flat bar or angle iron could be added to the sides of the tubing as well. A lot of heavy equipment attachments are made with solid plate in order to be strong enough. Often a high strength steel Like T1 is used. Dave

 

[JDknut]

135 Dave's points are right on. I say this as a professional engineer.

 

[Bill in IL]

I agree too you need higher carbon steel or an alloy steel.

I have a few projects in my future where I need higher strength steel but does anyone know where to find information about what is avaliable?

You mention T1 what is that? I have heard of A36 being 36 carbon therefore harder and higher strength but how does T1 compare to A36 or what else is out there that is readily avaliable?

 

[Anonymous-0]

You may want to ask over on the ACME and ACMOC boards, see if anyone can post photos from old literature and of land clearing jobs, seems the Rome Plow company, Fleco, LeTourneau, and other companies who built track type tractor attachments specifically for land clearing, may have produced a tree pusher, but after looking through the Rome and Fleco websites, nothing turned up, also checked on e-bay for old literature, can't say whether these were commercially built for sale or were designed and built just by contractors, for use by same, I've seen numerous photos of them posted over the years.

Someone on those other boards, particularly from Australia, may be able to be helpful here, as years back, land clearing and tree pushing was a popular method of clearing and tree pusher attachments seemed to have been popular.

The rome K/G type blade or whatever it was called then, was used by the 168th engineers battalion in vietnam, another attachment built for clearing.

I would imagine that after seeing some photos of the tree pushers used, like in Australia, it might be helpful in replicating a design that will stand up to the task, grade of steel, material selection, along with reinforcing needed to stiffen the attachment is probably the key to succeeding here.

 

[ChrisB]

I seem to remember similar devices from the military days where concrete was used to fill the tube.

Surprised no one has mentioned that.

Would the concrete not help the tube resist compression and bending?

 

[Anonymous-0]

Some listings of ASTM designations/specifications for tube, I'm not sure if there is a tube shape with an astm designation that would provide the strengths needed for this application, without unacceptable deflection, and or failure, without substantial stiffening. It also seems you would have to resort to building something from thicker dimension plate of appropriate steel to form like a box beam, really kind of guessing as it would also be apparent one would have to do a little formal engineering to determine some basic design that could be built to stand up to the loads imposed, lot of forces at work when point loading a member like this.

Also seems I recall those photos showing the pusher arms of the tree pusher, triangulated to a point, and both legs attached to the dozer blade trunions, not sure if bracing was used closer to the push point, hopefully someone can post some photos, no doubt they had something that worked without bending, should be helpful to you to see photos of them.
ASTM

 

[Anonymous-0]

T1 is a way higher tensile strength than regular mild steel plate. I think it is generally welded with 11018 rods. The way it was basically explained to me in school is that a 1/4in. T1 is equivelant to 1in. mild steel. Dave

 

[Anonymous-0]

Thanks. I'm not an engineer but have done a bunch of welding on Cats used for demolition. It's one of the most extreme conditions for equipment. Dave

 

[Anonymous-0]

You should be able to weld up a decent pusher bar without resorting to a full blown engineering analysis. If you're bending the bars you already have made, then obviously that indicates you either need thicker wall tubing and/or larger diameter tubing and/or better bracing and/or you're abusing them. I also think the suggestion chris made about filling the tube that's getting bent with concrete is a good one. This will stiffen the tube and make it much less likely to "bifurcate" or bend and fold under side loads. Lastly, of course when you've got the kind of power that a D8 can deliver you obviously have to use the bar properly or it's going to get bent. Any machine, or accessory (like a pusher bar) no matter how heavily built can be pranged if its not used properly or is abused. Take your time and square up on the tree accurately before *smoothly* putting the power to it. Finesse the blade elevation and yaw of the machine as power is applied and the tree starts to go over. Ensure the pushing force stays in line with the axis of the bar and without creating excessive side or vertical loading.

Above is a pic of a modern pusher bar. Note that it has teeth that dig into the tree. This keeps it from slipping up the trunk of the tree as you put power to it (otherwise which could also contribute to bending).

 

[BrianA]

Where does it start to bend? You might have to change to I or H beam in that area. I"ve built alot of attachments for larger dozers ,loaders and excavators. A pitcher of one bent might help figure out how to beef up that area. Does it bend sideways,up or down? If you could e-mail a pitchure I might be able to have a better input.