I have a concrete counterweight cast in the bottom half a 55 gallon barrel. I did cast a tongue into it, for pulling wagons and trailers or skidding trees. In the OPs original statement, he mentioned not having the luxury of welding. The nice thing about casting in concrete is you only need to hold the steel parts in position until the concrete sets. So he could bolt things together with small bolts or even wire the steel frame together until the concrete sets. Also, I didn't use much cement. Rather, I dumped the first bag or two of cement in the barrel, then added clean rocks, (softball to football size) as many as I could fit. I placed them, tamped them down rotated them and did everything possible to get in as many rocks as I could. This raised the level of the liquid concrete considerably. Then mix up a couple more bags and repeat. BTW, the rocks will be stronger than the concrete, but make sure they are clean, so the cement adheres to them well.
This works great, but if I did it again, I would add some improvements.
I made a framework for this kind of counterweight for a friend. I used a length of 2 1/2" square tube for a receiver hitch. I welded a piece of 1/2 or 3/4 pipe to the square tubing so it would come up flush with the top of the concrete, so he could have a long pin to retain whatever tongue he inserted into the receiver. I also suggested he cast in at least 1 piece of 4" PVC pipe, squashed slightly oval, so he could carry his chainsaw. And several 2" PVC, for an axe, a pick or shovel. He left about 3-4" of (plastic) barrel sticking above the concrete so he could carry a couple chains or other small objects ( saw file, tongs, gloves, clevis, etc) in the barrel. I also included a couple of different height tongues for log skidding, up near the top of the barrel.
If you do cast pipes in the concrete, be sure to go all the way to the bottom of the barrel so you can drill or punch a drain. In our neck of the woods, a couple inches of rainwater in the bottom of the hole will freeze and break the cement.
