The reduction of noise of narrow gauge lines is needed as well as Shinkansen noise of standard gauge lines. The noise of narrow gauge lines consists of rolling noise, traction motor noise and gear unit noise. The noise of traction motors has been reducing as DC motors with cooling fans outside have been replaced with Induction motors with cooling fans inside. However, as Induction motors are compact and driven at a high speed, aerodynamic noise generated from the cooling fans has become dominant. This aerodynamic noise has been eliminated by the adoption of high-pressure fans. Recently totally enclosed type traction motors using permanent magnet have been getting in the limelight for their high efficiency and low noise.

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