- #1

mudrat

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- TL;DR Summary
- Class 3 lever design, how to calculate buckling at force point.

Hello, I am a retired electrical engineer who likes to tinker and invent. As I am getting older I find the moving of logs is getting harder to do, so I am thinking of building a boom crane to attach to the 3 pt hitch on one of my tractors.

The design would basically be a class 3 lever, with a distance of 16" from fulcrum to force, and 48" from force to load. With a max load of 500#, the force is 2000#.

Using A39 steel tube, 2" square, I am wondering about what wall thickness to use. There will be a reinforcing plate at the force point and a tension strap/rod along the top, but I am looking to calculate based on the simplified design of point load and force without any reinforcement of the tube.

It has been way to may years since my basic strength of materials courses in university to remember the formulas. Searching the net has only brought up distributed load on beams. It did bring me to this site!

I would just like to get an idea of how to calculate the strength needed to prevent buckling at the force point.

Mudrat

The design would basically be a class 3 lever, with a distance of 16" from fulcrum to force, and 48" from force to load. With a max load of 500#, the force is 2000#.

Using A39 steel tube, 2" square, I am wondering about what wall thickness to use. There will be a reinforcing plate at the force point and a tension strap/rod along the top, but I am looking to calculate based on the simplified design of point load and force without any reinforcement of the tube.

It has been way to may years since my basic strength of materials courses in university to remember the formulas. Searching the net has only brought up distributed load on beams. It did bring me to this site!

I would just like to get an idea of how to calculate the strength needed to prevent buckling at the force point.

Mudrat