Dipper assembly and mining excavator

A dipper assembly comprises a dipper, a dipper door, a closure mechanism, and one or more block assemblies. The dipper door is pivotally mounted to the dipper, and has a closed position in which the dipper door covers the dipper bottom. The closure mechanism has a locked position and an unlocked position, and is coupled to the dipper back and the dipper door. In the locked position, the closure mechanism holds the dipper door in the closed position. In the unlocked position, the closure mechanism allows the dipper door to swing away from the closed position. The block assemblies are coupled to the dipper back and limit the rotation of a side connecting plate to a pre-defined angle that corresponds to the closed position.