Abstract: A hopper for receiving and discharging product in a weighing machine has a construction comprised by a removable body shell and a supporting chassis. The shell has an opening at the top for receiving product to be weighed and an opening at the bottom for discharging the product after weighing. A discharge door cooperates with the opening at the bottom of the shell body to support the weight of product within the shell during weighing and to discharge the product after weighing. A quick-release coupling permits the hopper to be firmly installed on the weighing machine and to be quickly removed from the machine without tools. A toggle linkage is employed to operate the discharge door and locks the door in the closed position without further locking mechanisms. A bi-directional actuator moves the toggle linkage and door into and out of the closed position.