Quote:
Originally Posted by RC1  By my calcs 25 KGF on the bar handle (mechanical advantage 9.25:1) = 231.25 on the lifting plate, which would then tip an evenly weighted up-right stem (notched by 1/3) of up to 925 KG. This calculation accounts for the pull created on the notched side of the hinge but not the bending factor of the hinge-wood itself, nor the friction caused by the point of contact between bar and wood.
Am I working this out correctly?
Reg |
First off Reg, great inventions, could've used that ratchet device on those darned cuban logs we had the other day.
Regarding your calculations .... I would just stop at saying there's 231kg of force applied by the lifting plate ... end of story.
The reason is for what you have discovered, friction, hingewood strength etc. Also the diameter of the log plays a difference as well as the height.
Imagine a short fat log weighing 1000kgs and a tall skinny one like a pine ... very different in getting them going over. With the tall skinny one it doesn't take much to get the centre of gravity beyond the hinge but the big one takes heaps.
As you know on a tall spar a wedge lift of 25mm in the back cut can move the tip 25cm but on a shorter fatter log not as much movement would occur.
Just my 0.02
