Abstract
The 2:1 roping elevator system shows complicated vibration behavior under a disturbance from the traction machine, because the disturbance does not only cause the vertical vibration to the car, but also induces the rotational vibration against the car's suspension sheave. To evaluate the relation between the sheave's rotational vibration and the car vertical vibration, an analytical model is introduced for the 2:1 roping elevator system. The eigen mode analysis indicates that the amplitude of rotational vibration mode against the car suspension sheave, which induces the car vertical vibration, increases more when the sheave is closer to the traction machine at the top floor. The model also reveals that the higher ordered mode of the sheave's rotational vibration in high-rise buildings interferes with the target rotational vibration mode, so that the mode coupling contributes to reducing the car vibration.
