Boom Pole

[RonMar]

Herringchoker is correct, you want the cantilever post at the point where the lower frame meets the boom(see pic). I like to break things down into lines of force. A weight applied to the end of the boom provides a downward force. This downward force is countered by the lift frame structure and the base of the boom attached to the tractor toplink fitting. Since these two points are not moveing, the boom tries to bend. the boom can't bend because the topstrap comes under tension preventing it. Since it can't bend, the boom pole is placed more under compression(stronger than shear or bending). The larger the diameter of the tube, the stiffer it is makeing it more resistant to bending under compression loads. The topstrap tension is transmitted back up over the cantilever to the base of the boom. This tension on the topstrap creates a downward compression force on the cantilever.

Because of this compression force on the cantilever, you want to have the cantilever larger at the base to distribute this force across the skin of the boom pole. If it is a small cantilever this concentrated force can distort/bend the boom pole. Better still would be a structure that surrounds the boom and instead of transfering this force to the boom, it transferes it around the boom and directly into the lift frame. The shape in the lower right of the pic shows what I mean, the hole represents where the boom would pass thru. The downward force of the cantilever would pass around the boom to the lift frame without damaging the tube.

 

[RobJ]

Sp I think I'm close?? Can't the attachment...saves assome sort of php file.

 

[rp4410]

Thought I would post a pic of my boom pole used for setting trusses when building pole barns. Works like a charm and was cheap to make.

 

[RobJ]

Thought I would post a pic of my boom pole used for setting trusses when building pole barns. Works like a charm and was cheap to make.

That one looks like a modifled TSC (or KingKutter) brand with an extended boom. One I was going to copy but didn't have a pipe bender. Wonder if it'll pick up a 525# FM...without a box on the back.