Safety switch

Abstract

A compact safety switch comprises a housing having an axially sliding ram mounted therein. The lower end of the ram is in contact with an actuating rod of a switch, which is aligned with the ram. The upper end of the ram lies against a cam formed in the outer surface of an indexing wheel. A pre-tensioned helical spring surrounds the lower end of the ram for holding the ram in place. The indexing wheel is provided on one end of the cam with a radial notch for locking a key inserted into the keyway and at an opposite end of the cam with a resting notch. The safety switch further includes an interlocking mechanism having a stator located concentric to the ram and an armature integral with the ram. With the key inserted in the keyway, the armature is pushed out of the stator and the upper end of the ram is held in engagement with the resting notch. The key cannot be removed from the keyway at this time and is not released upon shutting of the machine, as the corresponding rotation of the indexing wheel is prevented by the ram. Only when the machine comes to a standstill is the stator energized and the ram lifted from the resting notch. The upper end of the ram proceeds to travel along the cam on its high side, causing the lower end of the cam to be pushed against the switch, thereby forcing the switching circuit in the control circuit of the machine open.

Dependencies are inferred from the claim text.