US Patent 6935255 Auxiliary seed hopper having a removable screen

A pneumatic seed on demand delivery system comprises a frame having a main hopper and an individual planting unit. An air pump directs pressurized air to a nozzle located at the base of the main hopper. The seed in the main hopper is taken up by the air stream passing through the nozzle and is directed to an auxiliary hopper located on the planting units. The auxiliary hopper has sidewalls that are provided with an opening into which is inserted a removable screen for venting the interior of the auxiliary hopper. An exterior wall extends outward from the auxiliary hopper to protect the removable screen and is open at the bottom to vent air from the removable screen. The removable screen is trapped in the opening by a removable lid engaging the sidewalls of the auxiliary hopper.