This work presents the dynamic modeling of ball bearing which uses multibody dynamic formalism. Such formalism allows immediate integration of the model in dynamic simulations of helicopter main gear boxes. Ball bearing is considered non-lubricated in order to predict its behavior in case of lubrication system failure. Rolling contacts are treated with the method proposed by Kalker. This approach is based on polynomial approximation of relative displacement on the contact ellipse. For low computational cost and without any spatial discretization, it gives a good estimation of tangential traction and creep. Also, a regularization of the Kalker linear creep theory is proposed. It is used here to facilitate the global convergence of the Newton iterative process. It is well suited for multibody dynamic simulations which do not need a very fine treatment of rolling contact. A numerical example of a ball bearing under thrust load is presented.