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This paper analyzes different concepts for storage and recuperation of kinetic energy during braking operation in a forklift truck application. The reduction of fuel consumption is one of the challenges for on and off-road vehicles. Starting from a conventional hydrostatic transmission, secondary hydraulic control and a hybrid solution are investigated. Wasting kinetic energy during braking operation of mobile working machines in cyclic applications and converting it into heat energy instead of reusable energy is a very inefficient principle still used in industry. Rising energy costs, enhanced government guidelines and increased environmental awareness require more efficient drive concepts for the next decades. Recuperation of kinetic energy during braking operation provides the opportunity of increasing the efficiency of mobile working machines. Efficient recuperation of kinetic energy requires a proper application and a low-loss system design.

Proportional valves for hydraulic and pneumatic applications are well developed and the technology behind it can be considered mature. The paper focuses on valves that are already on the market as well as on developments which can be observed at universities and their institutes or departments. For both fields - meaning hydraulics and pneumatics - the trend of integrating digital electronics into the components is treated and discussed. Developments accompanying these innovations include miniature, micro and low power valves as well as standards to drive these valves directly from a field bus. However, also innovations on the mechanic, electric or fluidic side on valves are remarkable and will be introduced to the reader.

The simple, compact design and the high power and force density of linear-motion hydraulic actuators make them suitable for a wide range of applications in the machine building and systems engineering sectors. Linear hydraulic actuators do, however, demonstrate more elasticity with respect to the desired position than their electric counterparts by dynamically changing loads. The time response for maintenance of the desired position when subjected to dynamic load changes is referred to below as dynamic load stiffness. This article begins by considering the elementary principles of a cylinder's stiffness. Afterwards it then goes on to describe various approaches in an attempt to increase dynamic load stiffness and to present the simulation results for the different systems. Then it concludes by discussing these results and using them as the basis for an assessment of the potential of each approach.

Environmental aspects will have a major influence on the application of hydraulics in mobile systems in the near future. With the use of environmentally friendly fluids, these aspects can be fulfilled in a convenient way. Nevertheless there are differences between the well known mineral based oils and environmentally friendly fluids based on synthetic esters which represent a new mainly unknown fluid type. For a trouble free usage of these fluids in hydraulic systems, a founded knowledge of the fluid's properties and its interaction with hydraulic components is a basic requirment. For this purpose an application based testing of these fluids is essential.