tree pusher

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).

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

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.