RCS rotary blowers are heavy-duty units designed with integral- shaft ductile iron impellers having an involute profile. The headplates, gear cover, end cover and rigid, one-piece casing are grey iron. Carburized and ground alloy steel spur timing gears are taper mounted on the shafts, secured with a locknut. Cylindrical roller bearings are used on the drive end with ball bearings on the gear end. Piston rings reduce air leakage through the shaft openings in the headplates, and lip-type oil seals prevent lubricant from entering the air chamber. The RCS incorporates thrust control, with splash oil lubrication at both ends of the blower. All units are designed with detachable rugged steel mounting feet which permit in-field adaptability to either vertical or horizontal installation requirements. The top shaft is extended for drive on side outlet blowers, and either shaft can be extended for drive on top or bottom outlet blowers. All frame sizes are center-timed to allow rotation in either direction.