This paper describes a model which makes it possible to predict the transport velocity of a crushed rock material bed along an ordinary screen with a circular stroke, Transport velocity can be predicted with respect to the inclination, stroke and frequency of the screen. The model is based on physical laws. A particle leaves the screen surface when the negative vertical acceleration of the screen surface exceeds that of the particle. The particle can also slide along the screen surface. Monte Carlo simulation is used to estimate the influence of the other particles. Thus, random values are used to simulate the collisions between particles. The predicted transport velocity is equal to the average transport velocity from a few runs with the model. To verify the model experiments were made; the transport velocity of a bed of crushed rock particles along a wire cloth was measured for different inclinations, strokes and frequencies. The predictions made with the model agreed well with the experimental results. A model which makes it possible to predict the size distribution of both the remaining and the passed material on a screen with several interacting screen planes has already been presented by the author. In addition, it is necessary to know the transport velocity of the material to be able to estimate the bed thickness and the capacity of the screening process. (C) 2002 Elsevier Science Ltd. All rights reserved.