The drive system is a key component of an elevator installation that supplies energy into the system, coupling the car-rope and
the counterweight-rope subsystems. However, it often becomes a source of excitation that is responsible for vibrations that compromise
the car ride quality. In this paper a non-stationary distributed-parameter model describing vertical dynamics of an elevator system that
accommodates the drive machine, the car, the counterweight and the suspension ropes has been developed. The model is used to analyze
the influence of the drive machine on the elevator system performance. The dynamic behaviour is described by a set of partial differential
equations. Those are discretized by expanding the vertical displacements in terms of the linear mode shapes to obtain a set of ordinary
differential equations. The mode shapes correspond to a system composed of three masses constrained by a suspension rope. The discrete
model is then solved numerically in Matlab-Simulink using parameters of a real installation. The numerical simulation results predict
transient resonance phenomena in the system