Abstract: An automatic sweep for a sliding door includes a seal member that is coupled to a housing at the bottom end of the door for movement between a raised position when the door is open and a lowered position when the door is closed, in which the seal member provides an acoustical seal for the gap that would otherwise exist at the bottom of the door. The sweep is actuated by an over-centre linkage that co-operates with an abutment adjacent the door opening. As the door reaches its closed position, the linkage is displaced from a normal extended configuration to an angled configuration, which laterally displaces an operating rod connected to a leaf-spring that then presses down on the seal member to move the member to its lowered position. When the door is opened, the over-centre linkage is moved back to its extended configuration, the rod is displaced in the opposite direction, and the leaf-spring raises the seal member.