A discharge gate arrangement for railroad hopper cars having longitudinally extending discharge openings arranged in a horizontal plane beneath the hopper. Gate members arranged in pairs swing in opposite directions transversely of the car. Each gate member is pivotally hung and attached to an operating mechanism that includes a transversely extending shaft having two oppositely threaded portions. The operating mechanism includes split nuts located on the threaded shaft portions with attached links connected to the gate members in order that rotation of the shaft in one direction moves the split nuts in opposite directions and causes the cooperating gates to open and close simultaneously.