Abstract: The air-cooled type induction motor used for railway vehicles such as the electric car generates sound waves (noise) which are uncomfortable to the ears of the human being when it is rotated. An induction motor according to the present invention has therein a plurality of waveguide (or air guide) plates for efficiently exhausting air, which serves to cool the motor, outside the motor. These waveguide plates are arranged not to resonate with the frequency of the sound waves which are generated by the cooling air. The sound waves are guided outside the motor through the waveguide plates before it is amplified to a noise level which is uncomfortable to the ears of the human being. Noise caused when the motor is rotated at high speed can be thus eliminated.

Abstract: In apparatus for exchanging a control rod drive mechanism of a nuclear reactor of the type comprising a horizontal platform supported to be rotatable in a working chamber disposed below a reactor pressure vessel and a traveling carriage traveling on a rail assembly laid on the platform, there is provided a beam attached to the traveling carriage to be swingable between the vertical and horizontal positions and provided with a carrier for vertically moving the control rod drive mechanism. A holding device is secured to the beam so as to hold the control rod drive mechanism when the beam is moved to the horizontal position. The bolts which are used to connect the control rod drive mechanism to a housing in the pressure vessel are loosened and clamped by a bolt mounting device, which is conveyed in and out of the passage of movement of the carrier.