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: A ring tenser for a twisting machine. The ring is loosely fitted from above a head portion of the tenser body having a shoulder formed on an outer circumferential surface thereof and is placed on the shoulder of the tenser body so that a yarn unwound from a package is passed between the ring and the shoulder. One of the head portion of the tenser body and the ring is made of a metal material while the other includes a magnet.

Abstract: A connecting pin with a cross-section comprising vertical and horizontal wing portions. For better connection, opposite surfaces of the pin are changed to form projections. Due to this configuration, the pin can connect two articles with a certain play in one or more directions. The pin can be formed integrally with one of the articles.

Abstract: A pneumatic yarn guiding apparatus for a double twisting machine, two-for-one twister. A yarn passage of the double twisting machine is formed by a yarn guide tube vertically movable inserted in the tension device mounted in the center of a yarn supply bobbin, a yarn guide hole formed in the center of a stationary disc through the center of the spindle, a yarn guide tube formed in the radial direction of a yarn store disc, a yarn passing space formed between a rotary disc secured to the spindle and an outer ring, and a vertical space between the outer cylinder of the stationary disc and balloon restricting cylinder.