Dynamic rope loads and traction ratios under adverse lift operating conditions

The lift safety codes demand that the dynamic traction conditions must be investigated in addition to the static conditions. This includes evaluation of the traction ratios under emergency braking conditions. For safety reasons, the systems calculations involve the evaluation of dynamic suspension rope tensions on the car and counterweight sides of the traction sheave and seek to guarantee that during normal operation/ car loading and emergency braking conditions slippage between ropes and traction sheave does not occur. In this paper rope the determination of tensions under dynamic loads arising due to sway of tall buildings caused by diverse environmental issues such as strong wind and earthquake conditions is discussed. The tensions during the lift travel are computed and the corresponding dynamic traction ratios for the worst cases depending on the position of the car in the well are assessed. The additional dynamic effects are analysed, and it is demonstrated that to make an accurate estimate of the applied traction conditions these effects should be assessed.