This thesis deals with innovative working hydraulic systems for mobile machines. Flow control systems are studied as an alternative to load sensing. The fundamental difference is that the pump is controlled based on the operator’s command signals rather than feedback signals from the loads. This control approach enables higher energy efficiency and there is no load pressure feedback causing stability issues. Experimental results show a reduced pump pressure margin and energy saving potential for a wheel loader application. The damping contribution from the inlet and outlet orifice in directional valves is studied. Design rules are developed and verified by experiments. A novel system architecture is proposed where flow control, load sensing and open-centre are merged into a generalized system description. The proposed system is configurable and the operator can realize the characteristics of any of the standard systems without compromising energy efficiency. This can be done non-discretely on-the-fly. Experiments show that it is possible to avoid unnecessary energy losses while improving system response and increasing stability margins compared to load sensing. Static and dynamic differences between different control modes are also demonstrated experimentally.

Mobile Working Machines are defined by three characteristics. These machines have a cer-tain task of doing a working process, they are mobile, and they have a signifi cant energy share in their working functions. The machines should be as productive, efficient and of high quality as possible. All these machines in the fi eld of agriculture, forestry, construction, logistics, municipal sector, and in other special applications work in different applications. But, many technologies placed in the machines are the same, similar or comparable; therefore, different branches can learn from each other. Mobile Working Machines provides a wide and deep view into the technologies used in these machines. Appropriate for new engineers as well as those who wish to increase their knowledge in this field, this book brings together all the latest research and development into one place.

This book shows an independent metering electro-hydraulic control system involving its flexible hardware layouts, complex software control, representative products and applications. The book includes one chapter introducing the background and motivation of the independent metering electro-hydraulic control system. It also includes one chapter to summarize various hardware layouts involving the utilized hydraulic components and circuits, as well as analyze their advantages and disadvantages. It emphatically consists of four chapters demonstrating the detailed multivariable control strategies from three levels: load, valve and pump, together with fault-tolerant control under the fault condition. It includes a last chapter, in which products of independent metering control valve and their applications in some typical heavy-duty mobile machinery are collective works of reviews illustrative of recent advances. This book is interesting and useful to a wide readership in the various fields of fluid power transmission and control.

More and more vehicles are being electrified. Mobile working machines and heavy trucks are not excluded, and these machines are often hydraulically intense. Electrification entails new requirements for the hydraulic system and its components, and these requirements must be taken into consideration. Hydraulic systems have looked similar for a long time, but now there is an opportunity to advance. Many things change when a diesel engine is replaced with an electric motor. For example, variable-speed control becomes more relevant, electric regeneration becomes possible, and the use of multiple prime movers becomes an attractive alternative. The noise from the hydraulic system will also be more noticeable when the diesel engine is gone. Furthermore, the introduction of batteries to the system makes the energy more valuable, since batteries are heavy and costly compared to a diesel tank. Therefore, it is commercially viable to invest in the hydraulic system. This thesis revolves around the heart of the hydraulic system, that also is the root of all evil. That is the pump. Traditionally, a pump has had either a fixed displacement or a continuously variable displacement. Here, the focus is on something in between, namely a pump with discrete displacement. The idea of discrete displacement is far from unique, but has not been investigated in detail in combination with variable speed before. In this thesis, a novel design for a quiet pump with discrete displacement is presented and analysed. The results show that discrete displacement is relevant from an energy perspective for machines working extensively at high pressure levels and with low flow rates, and that a few discrete values are enough to make a significant difference. However, for other cycles, the possible energy gains are very limited, but the discrete displacement can be a valuable feature if downsizing the electric machine is of interest.

Hydraulic Systems for Mobile Equipment is the gold standard for hydraulics instruction, offering a comprehensive, single-source resource for introductory and advanced content. It provides very detailed, high-level instruction for students studying to become professional mobile hydraulics service technicians. With a primary emphasis on agricultural and construction machinery, it can also empower students working in any related field of hydraulics. The textbook is correlated to the competencies of the AED Hydraulics/Hydrostatics and Administrative/Safety Standards and the ASE Education Foundation Heavy Trucks Task List.

This unique textbook takes the student from the initial steps in modeling a dynamic system through development of the mathematical models needed for feedback control. The generously-illustrated, student-friendly text focuses on fundamental theoretical development rather than the application of commercial software. Practical details of machine design are included to motivate the non-mathematically inclined student.

A unique resource that demystifies the physical basics of hydraulic systems Hydraulic Control Systems offers students and professionals a reliable, complete volume of the most up-to-date hows and whys of today's hydraulic control system fundamentals. Complete with insightful industry examples, it features the latest coverage of modeling and control systems with a widely accepted approach to systems design. Hydraulic Control Systems is a powerful tool for developing a solid understanding of hydraulic control systems that will serve the practicing engineer in the field. Throughout the book, illustrative case studies highlight important topics and demonstrate how equations can be implemented and used in the real world. Featuring exercise problems at the end of every chapter, Hydraulic Control Systems presents: A useful review of fluid mechanics and system dynamics Thorough analysis of transient fluid flow forces within valves Discussions of flow ripple for both gear pumps and axial piston pumps Updated analysis of the pump control problems associated with swash plate type machines A successful methodology for hydraulic system design—starting from the load point of the system and working backward to the ultimate power source Reduced-order models and PID controllers showing control objectives of position, velocity, and effort