I grabbed a random youtube. I could not find one that showed underside better that was not done by a company (advertisement). The one end of the platform, dumpster, or what ever has a set of 4” by 6” steel wheels this is normally the end that opens if there is a door. The other end has a large hook at the bottom. There is a set of steel box tubing that runs from end to end under the bottom. The trailer or truck has a
Discuss this in the forum topic Hook Lift Trailers.