The dipper/bucket is the digging and loading tool on the mining shovel. 

Dippers can be as large as 12 x 12 x 15 feet with nominal volume and weight payload capacities up to 80 cubic yards and 100 tons. 

The dipper has a bottom swing door which is latch closed during digging and drops open to dump the payload into the truck bed.    

The dipper door itself has a weight of 25,000 pounds and a full load on the dipper door is up to 110 tons. The door commonly has damping devices to eliminate unrestrained swinging and to prevent impact damage from "banging" and "slamming."