Beside drive tasks for feeding movements and tool clamping, fluid power systems especially permit the temperature control in machine tools: They allow cooling or pre-heating of both single components and complete assemblies (e.g. frame components, drive motors and spindles). In this respect, fluid power systems are an important element for controlling and managing the thermo-elastic behaviour of machine tools. As an essential part of the machine, they must be included from the beginning of the design studies of machine tools – particularly in terms of accuracy under conditions of energy-efficient manufacturing. The increasing complexity and performance of fluid power systems generally lead to an increased use of auxiliary power. This has to be critically examined from an economic and environmental point of view. Focusing especially on the optimum thermal performance with minimum power supply, existing simulation models are not adequate for a scientifically based design. The complex system structures as well as the lack of basic investigations and design tools lead to a thermal optimization problem that is not solved satisfactorily today. For this purpose the Institute of Fluid Power (IFD) develops principles and simulation models with a holistic approach. Based on the analysis of general tooling machines fluidic subsystems are identified and essential modelling requirements are specified. From a fluid-technical perspective the motor spindle represents an important principal component, and therefore, is a particular focus of current investigations. Starting from the basic technical structure of the motor spindles an