Volvo Technology has earlier developed a free piston engine prototype and tested it. It was found that a new bearing design was needed for the translator and piston in order to reduce friction losses and thus improve operational life and efficiency. These conclusions led to this master thesis project which has been carried out during a time span of 20 weeks. A large literature- and concept study has been carried out, resulting in a number of promising concepts to solve the bearing problem. A combined aerodynamic and aerostatic bearing for the translator was chosen for the investigation. A theoretical study has therefore been carried out together with static and dynamic rig test in order to verify the theoretical results and evaluate the opportunities of using it in a full-scale prototype. The rig tests were shown to function and correspond well to the theoretical results and it was concluded that the aerostatic bearing concept chosen, was very promising. It was found that a supply pressure of 4bar would manage to keep the translator centred which resulted in an energy consumption of barely 200W.