The invention is an improved rotary seal which is particularly well suited for protecting the bearing area in a conveyor idler roll. The seal has inner and outer annular members which normally rotate freely without contact relative to each other. The members have cooperative means to form a labyrinth effective to restrict the ingress of contaminant or the egress of lubricant to or from the bearing area. One of the members further includes an attached annular disc of resilient flexible material. When the lubricant pressure in the bearing area increases, such as when the bearing is being regreased, it forces the free edge of the disc into contact with the other member to form a barrier against the leakage of lubrication. When the lubricant pressure normalizes, the resilient disc recovers to its normal, noncontact position.