Patent ID: 7207303

Claim:
A switch element for valve shut-off, fabricated as a cam follower for a plunger rod valve drive of an internal combustion engine, the switch element comprising an outer part and an inner element axially movable in the bore thereof and guided vis-à-vis the outer part by way of an anti-rotation safety element, the outer part having an annular groove inside the bore and the inner element having a radial bore with two diametrally opposed pistons that are displaceable into the annular groove, to couple the outer part and inner element in their relative positions achieved via a lost-motion spring, wherein the pistons have a planar surface as a contact area to face an under side of the annular groove, the annular groove is intersected by at least one oil port offset in a circumferential direction from the pistons, the outer part has an anti-rotation guidance component for anti-rotation guidance of the switch element relative to a surrounding structure, and a hydraulic clearance equalization element having a pressure system is installed in the inner element, and wherein the anti-rotation safety element is separately located from the pistons and the annular groove, and maintains the offset between the at least one oil port and the pistons by substantially preventing the inner element and the outer part from rotating with respect to each other, such that hydraulic fluid inserted through the at least one oil port can propagate along the annular groove towards the pistons for displacing the pistons away from the annular groove.