Abstract: A fanless salient pole DEM is provided with annular shrouds fitted to the stator ends in close juxtaposition to the rotor to isolate the rotor from atmospheric pressure during operation of the DEM.

Abstract: A commutator type, prior art dynamoelectric machine normally has an inlet for cooling air at the end of the machine remote from the commutator. The air flows from the inlet through axially extending passages in the rotor, outwardly through spaced radial ducts in the rotor, and into the air gap. Part of the air flows through the air gap to a collecting chamber at the commutator end of the machine to be discharged or exhausted. Part of the air flows radially outwards through interpolar spaces in the stator, through cooling ducts in the magnet frame to a peripheral passage which is connected to the collecting chamber at the commutator end. This invention provides a second collecting chamber at the drive end of the machine opposite the commutator end, communicating with the air gap and also with the peripheral passage at the drive end. Thus the air flow is divided after passing through the rotor and flows to the nearer collecting chamber providing a shorter flow path.

Abstract: In a commutator formed by a plurality of commutator bars clamped between an annular shell and a clamping ring held together by studs, the life of the commutator may be extended significantly by imposing a resilient damper between the stud and the inside wall of a passage in the shell or ring, or both. The damper is spaced inwardly from the end of the stud, preferably by an amount approximately equal to one third of the length of the stud.