Abstract: A variable geometry turbine for a turbocharger has a plurality of vanes disposed in an inlet passageway of a turbine housing outboard of the turbine wheel. The vanes are movable so as to adjust the effective cross-section area of the inlet between a first position in which the area of the inlet is a minimum and a second position in which the area of the inlet is a maximum. The movement of one end of the vanes is supported by a plurality of first guide tracks, such as slots, defined in a guide member. A vane actuator such as, for example a unison ring, effects movement of the vanes. The vane actuator has a plurality of actuation tracks (e.g. slots) for engagement with the vanes and is rotatably disposed in the housing. When it rotates the vane actuator induces sliding translation of the vanes relative to the first guide tracks in a first direction and sliding translation of the vanes relative to the actuation tracks in a second direction so as to adjust the cross-section area of the inlet.