A hopper grain trailer is a large trailer used to haul grain that is distinguished by traps below the trailer to release the grain from the bottom. The trailer is filled from the top by agricultural equipment and covered by a rolling tarp.
Once the trailer is filled, it can be attached to commercial grade trucks to be hauled to other facilities. The traps on the bottom of the trailer provide for an easy release of the grain, using gravity instead of additional equipment. The traps are typically cone-shaped in order to direct all the grain to the trap door, allowing the trailer to be emptied more efficiently.