Door locking mechanisms for hoppers

Claim 1

For a hopper structure having a sloped bottom wall terminating at a lower end in a discharge opening; said hopper structure including a door hingedly connected thereto for swinging movement between open and closed positions relative to said discharge opening, the improvement of a locking mechanism comprising: a keeper element on said door, a bracket on said hopper connected to said sloping bottom wall, a latch member having first and second ends, including a keeper receiving jaw at said first end thereof, means mounting said latch member on said bracket for pivotal movement about a first horizontal axis, a first link connected to said second end of said latch member for pivotal movement about a second horizontal axis parallel to and spaced from said first axis, a bell crank lever mounted on said bracket for pivotal movement about a third horizontal axis spaced laterally from and being parallel to said second axis, pivot means connecting said first link to said bell crank lever for movement about a fourth horizontal axis parallel to and spaced from said third axis, a first toggle lever connected to said bell crank for pivotal movement about a fifth horizontal axis parallel to said fourth axis, a second toggle lever pivotally connected to said first toggle lever, biasing means connected to said bell crank lever urging said pivot means of said first link and fourth horizontal axis to an over-center position relative to a generally horizontal plane extending through said second and third horizontal axes wherein said keeper receiving jaw is in locking engagement with said keeper element to maintain said door in a closed position.