Abstract: A crosshead extruder having an extruder housing with a throughlet passage for cylindrical workpieces to be coated with a highly viscid material such as unvulcanized rubber. The crosshead extruder includes an extruder nozzle for defining the thickness of such coating, a side inlet for supply of a pressurized coating material to the extruder housing, and an interior power driven worm member for receiving the pressurized inlet material and conveying the material around the workpiece passage and forwardly towards the extruder nozzle. The coating material is present at the extruder nozzle all the way around the workpieces even when the workpieces are of a large diameter.