an improved drum motor , preferably electronically commutated , features a unitary stationary central shaft supporting a stationary inner stator , and an external rotor , including permanent magnets , secured to an inner surface of a generally cylindrical rotatable casing part . this permits variable speed operation while avoiding any need for an internal gear linkage . safety is improved by making sealing plates at respective axial ends of the casing stationary , and providing an annular peripheral seal around each sealing plate . respective rolling bearings near each end of the casing facilitate rotation of the external rotor relative to the stator , and a clamping arrangement minimizes noise from the bearings .