Experimental railway research focused on the laboratory study of rail vehicle dynamics allows avoiding expensive field tests and reduces the cost of the development of new vehicles as well as making it simpler to improve design characteristics for existing vehicles. An example of such research is the investigation of the dynamic behaviour of a wagon suspension performed with the full-scale rail vehicle test rig in the CRE High Lab at Central Queensland University. Commonly, at the design stage of a test rig, it is necessary to estimate the working behaviour of different subsystems such as electrical, hydraulic, etc. It is possible to do this in two ways, either by means of the on-line or real-time simulation processes. The first process is adequate but it does not take into account all the nuances of the system configuration and does not allow testing of the equipment used in subsystems. Therefore, the optimal method is the usage of the real-time simulation process, which is also called hardware-in the-loop simulation. One of the major requirements of such an approach is the accurate representation of the behaviour of subsystems in the real-time mode. A real-time wagon model was developed based on the Gensys multibody simulation software version running under the Realtime Linux kernel open source software compiled and distributed by Open Source Automation Development Lab. In this paper, the authors focus on their simulation and verification methodology. All results obtained are presented and limitations are discussed. The discussion on real-time simulation methodology should help with the development and verification of rail vehicle test rig design at the early stages, leading to the reduction of design errors and related equipment failures