Pivoted Lifting Arm

[djt1967]

I'm having one of those weeks.....

I've got a pivot arm with a load of 1250kg on the end. The arm is 400mm long from the pivot centre. The pivot shaft is 60mm Diameter. When the lifting arm is in the lifting position it is supported by a stop block 230mm from the end. I'm making the assumption that every thing is made from mild steel.

I need a calculation to determine if the arm can take the load and if I can reduce the pivot shaft diameter.

I've attached a drawing of what I'm talking about.

Thanks in advance for any help you can give me.

 

[desertfox]

Hi djt

Use the stop block as the pivot and workout the reaction on your shaft end using simple levers, check then for shear and bearing stress against whatever the shaft is supported on.

Regards

desertfox

 

[rb1957]

the piicture isn't particularly clear to me ... the load is applied to "drop" the arm, rather than "lift" it (maybe it's just semantics).

"When the lifting arm is in the lifting position it is supported by a stop block 230mm from the end."

i assume you mean that the load is applied (tangentially) when the arm is in the "up" position, and the arm stops moving when it hits the stop ... sounds like an impact load to me. if the arm has no resistance (friction, dampening springs, ...) then it'll really "wack" into the stop.