Valve gear for an internal-combustion engine

A valve gear for controlling the gas exchange in internal-combustion engines with a valve spring which holds a valve in its required position at all times and is clamped between a valve head and a valve-spring support which is adjustable in the direction of the valve axis, wherein the adjustable valve-spring support comprises two nested setting rings (2, 3) which are rotated in opposite directions and at which the inner setting ring (2) has a collar (5) for supporting the valve spring (12) and is movable in the direction of the valve axis by means of the rotation relative to the outer setting ring (3), the setting rings having elements (9, 10) to prevent return rotation.