An exhaust apparatus for a differential exhaust mechanism having a labyrinth seal and a plurality of vacuum pockets includes a differential exhaust system for evacuating the vacuum pockets and an exhaust system for evacuating a chamber of exhaust gas. The differential exhaust system and the exhaust system are connected by control valves that can be opened and closed, enabling communication between the vacuum pockets and the interior of the chamber to be opened and closed (or connected and disconnected) as well. The valves are opened when a vacuum is being formed inside the chamber or when a malfunction occurs in the exhaust system, thus connecting the vacuum pockets and the chamber and preventing excessive pressure from building up on the hydrostatic bearing.