I know that mine will shear through willow trees as big as will fit between the guides and doesn't even flinch. The belt has never slipped to my knowledge. And like sparkplug says, I'd prefer a belt to slip rather than the pitman arm breaking on the 'older' style.
Well I tried to shear a 24 inch hack berry with mine. It worked good, sheared the entire mower off the tractor. It worked great clearing the pond edge before that. Now it no work at all.
