Manipulation proof combination lock

Abstract

A combination lock is provided having a housing with a lock dial shaft rotatably mounted thereto. A lock bolt is slidably mounted to the housing, and a fence lever is pivotally coupled to the lock bolt. A tension spring constantly urges the fence lever into an operative, lock bolt displacing position thereof. An assembly of gated tumbler wheels is rotatable by the lock dial shaft and a slotted disc is mounted on a tumbler wheels assembly. The fence lever is adapted to close against the gated tumbler wheels when in alignment and thereby enabling the displacement of the lock bolt by the fence lever. A displaceable spring cam plate is coupled to a cam disc associated with the slotted disc so that, on every revolution of the cam disc, the plate becomes displaced a short distance. A second spring coupled between the fence lever and the cam plate is effective in the non-displaced position of the plate to restrain the pivoted movement of the fence lever under the tension of its spring. In the displaced position of the plate, the fence lever is allowed to pivot into the operative position thereof.

Dependencies are inferred from the claim text.