Abstract: A lock for dumpsters having a free-swinging weight with an attached hook all of which is enclosed in a steel box and mounted inside a trash dumpster. A hanging chain is mounted to a steel plate which in turn is mounted to the lid of the dumpster in such a way as to hang in position where it will be grasped by the aforementioned hook when the lid is closed. Mounted outside the dumpster is a steel plate with a hole drilled such that it will line up with a bar and dowel mechanism mounted on the turning axis of the weight. By inserting a specially made key from the outside through this hole, the dowel may be turned which rotates the weight and releases the chain so the dumpster lid may be opened. In the case of key duplication a standard padlock will restrict the use of any key. A tipping of the dumpster, as occurs when a trash truck dumps it, will rotate the weight by gravity and thus release the chain and open the lid so the load will fall out into the truck.