Regulating slide valve comprising a valve body having a valve opening, and a valve plate which has two side surfaces and which is displaceable along a displacement path between an initial position in which it releases the valve opening and an end position in which it completely covers the valve opening, this displacement path forming the regulating area of the valve; wherein the valve plate has a contact ring on one side surface, which contact ring projects over the side surface of the valve plate and is mounted at or in the valve plate by a spring device, can be pressed in against the spring force of the spring device in the direction of the valve plate and contacts a contact surface of the valve body at least over a portion of its circumference in the end position of the valve plate.