I'm guessing the issue is that the load is cantilevered out the back of the machine. The stress this puts at the fulcrum can be very large. Wood can't take much load (tension) at all across the grain, or it will just split.

Making something out of metal will be much more durable. However, I would look to make the structure has triangulation to put the load in tension or compression, not to have the support members in bending. (Heavy loads)(lever arms)(extra acceleration due to bumpy road)=failure (not personal failure, but the bending/breaking of the bracket).

You may also want to look into allowable tongue weights on the ATV. Hanging a load off the back (especially behind the hitch) may be putting stresses beyond the design limit on your frame, or may lead to low contact forces at the front axle, which could lead to poor stability or steering (especially if you have to drive up hills), and in extreme loading, lead to a wheelie.

I love your farm, and getting a view into your life. I do a little sustainable/permaculture gardening, but living in the suburbs haven't/can't go all in. But I can satisfy my fantasy/longings by watching and reading. I've learned much from your lunchtime series.

Thanks for a great blog!

Mark,

Looking at the picture in the "ATV garbage hauler details" article, a couple of remarks;

• the place in the 2x6 where you put the hole in is the most heavily loaded spot. By making a hole there you are effectively concentrating the stress in the wood on the most heavily loaded spot, making the structure weaker.
• you placed the beam so that you have a 6" width and a 2" thickness. Rotating the same beam 90 degrees so that the thickness is 6" and the width 2" would give a structure that is 9x as stiff and 3x as strong using the same amount of wood.

Consider using two 2x6 beams in parallel (placed so they have a 6" height) with some spacers between them so that the framework they form fits over the upright steel beam. The only weakness of such a ladder structure is that is not very stiff in torsion.

So better yet, use two 2x6 beams (placed with the 6" vertical) a foot apart and two pieces of plywood on top and bottom to make a box. That would give higher bending and torsional stiffness and higher strength. You'd have to use some extra pieces of 2x6 to strengthen the place in the bottom plywood sheet where you'd cut the hole to fit the whole thing over the upright beam.

Since you like building things, read up some on mechanics of materials and construction principles. Investing in acquiring such knowledge will pay for itself many times over.

@Jim: A triangulated metal structure (space frame) is indeed one of the most efficient structures w.r.t. amount of metal used. The fabrication effort on the other hand is much higher than e.g. simply building a wooden box-beam. Your comments about overloading the frame or influencing the stability are spot-on. I was thinking the same thing.