US Patent 7246828 Refined anti-animal container lock

A lock for locking a lid to a receptacle has a bolt extending into aligned holes in overlapping parts thereof. A handle is detachably connected to an outer end of the bolt for pulling the bolt. An expansion mechanism in the form of wedges, a chain or other mechanisms, expands to an expanded geometry larger than the aligned holes to prevent withdrawing the bolt, and contracts to a contracted geometry which is at most equal to the dimension of the aligned holes for allowing withdrawing of the bolt. An actuator mounted in the bolt engages the expansion mechanism for moving it from the expanded geometry to the contracted geometry when the actuator is pushed. A biasing spring engaged to the actuator biases it in the withdrawing direction.