This study deals with the design of variable displacement oil pumps, with particular focus on wear of the inner components. A multibody model has been developed in order to achieve detailed knowledge on the dynamic loads which the main components are subjected to and to carry out a comparative analysis between different pump designs. A qualitative correlation, between the resulting wear following endurance tests and simulation results, has also been found. Design guidelines leading up to a good pump reliability have been obtained as a result of this activity