A gate valve for a system controlling cooling in a turbomachine is disclosed. The gate valve includes a gate mounted so that it can pivot about an axis between a position in which it shuts off an air passage orifice and a position in which it opens the orifice, and a rotating device for rotating the gate about the axis. The rotating device includes two superposed coaxial rotary members collaborating with one another via cam surfaces designed such that rotating the first rotary member from the shut-off position causes a translational movement of the second rotary member and of the gate along the axis of rotation followed by a rotation of this member and of the gate about this axis.