Freedom from maintenance and affordable manufacturing costs are required with this application, as it is intended for use as a water pump in developing countries. In this case the energy conversion principle of the Stirling motor is used to convert the thermal energy from sunshine into mechanical energy. Eight different igus® plain bearings made of the materials iglidur® G, M250 and the high temperature-resistant iglidur® X are fitted in the pump and produce the various pivoting and linear motions in a durable and cost-effective manner.