The present invention relates to industrial fasteners and more particularly to an over-center toggle latch.
Latches to join two members, for example, two panels, so that they may be separated and rejoined, have been developed over many years. Such latches are commonly used to secure container lids, trunk lids, panel doors and for industrial applications. A toggle latch provides the advantage of being relatively secure against accidental opening after it has been closed.
At the present time toggle latches are generally constructed with a bracket, an operating lever, a pivotable hasp (drawbar), an internal spring means if spring-loaded, and one or two pins pivotally mounting the lever and movable hasp on the bracket. That construction is relatively complex and expensive.
A relatively simple fastener is shown in U.S. Pat. No. 4,049,301 to Peter Schenk which is entitled "Toggle Latch". The operating lever (handle) is pivotally mounted on the bracket by a first pin and the drawbar is mounted to the lever by a second pin. The drawbar is spring metal which is corrugated to provide spring action.
In U.S. Pat. No. 4,025,094 entitled "Overcenter Latch" a handle member is pivoted on one pin and a tension member pivots on a second pivot pin. In U.S. Pat. No. 3,026,133 to Swanson, the handle member pivots on a first pin, a coil spring in a housing pivots on a second pin on the handle member, and the movable hasp (link) pivots on a third pin on the handle member. Two patents (U.S. Pat. Nos. 3,847,423 and 4,243,255) to Rexnord, Inc. show the use of an internal coil spring in a toggle latch, both of which are relatively complex. U.S. Pat. No. 4,065,161, entitled "Container Or Panel Clamp", shows a simpler device in which the movable hasp (drawhook) is a wire member with a spring loop along its length. U.S. Pat. No. 2,820,995 to E. Schlueter, entitled "Spring Loaded Lock Fastener", shows a slidable hasp pivotally mounted, and spring-loaded, by spring wire pivot members. It is not a toggle latch, but rather operates by a cam mechanism.