This paper presents a comparison study of the required thermal management of the open and closed circuit
hydraulic hybrid system. The hydraulic and thermal system behaviour of the open and closed circuit systems
were successfully modelled using a lumped parameter approach. The temperature of both open and closed circuit
systems have been compared using different cooling conditions based on the UDDS driving cycle. The
simulation results show that the open circuit systems have the potential to require smaller heat exchangers as
compared to closed circuit systems. In addition, the open circuit system consumes less power from the prime
mover and incorporates a smaller charge pump.

Functional safety standards define safety levels based metrics calculated from reliability of a safety function
components. However, calculated metrics rely on assumptions suitable for electronic components, and do not
reflect correctly reliability of hydraulic components. Such components are better described by a Weibull
distribution, but due failure rate not being constant on time, it is more complex to determine metrics and are not
considered in functional safety standards. This paper offers a method of how to consider such reliability models,
and study the behaviour of a safety function by consideration of Weibull distribution on hydraulic valves.

An overview to the performed analysis and lessons-learnt from flight control & hydraulic designers’ perspective on a condition monitoring (CM) concept for helicopters (H/C) hydraulic pump is given. A selection of already performed studies on condition monitoring applications for hydraulic pumps is discussed and the main obstacles in the CM implementation process for H/C hydraulic pumps are drawn from it as lessons-learnt. It is considered unavoidable to enter the CM concept by a data collecting and processing phase. Thanks to the CM hybrid algorithm continuous maturity improvement by data feeding, the obtained in-service data will be then directly used to identify the failure in real-time. In parallel, the data trend evolution analysis should allow to decide if it can be used also as a predictive element into the CM system for the dedicated failure mode.

Maximum and fatigue loads determine the dimensioning of rotor blades for wind turbines. Due to the large inertia of blades with weights above 35 tons, the reduction of loads via dynamic pitching of blades has a limited effect. Known from aviation, the trailing edge flaps (TEF) have been subject of recent research in wind energy, however there is no commercial solution for a practical implementation till now. The paper presents the development of a novel solution for trailing edge flaps. Experiments carried out at a test section of a 44 m rotor blade are evaluated.

In order to improve power efficiency in hydrostatic bearings a research project was found to minimize the leakage in this type of bearing. One concept for this solution is to use greases as lubricant. The non-Newtonian behaviour of greases which is determined by a characteristic yield stress builds the point of interest. The scope of this paper was to examine if self-sealing is reachable in a thrust bearing and can be predicted by simulation. Therefore an experimental setup and a numerical calculation model were developed. The results confirm the hypothesis and define possible operation conditions for this approach in the field of hydrostatic bearings.
Keywords: non-Newtonian fluid, tribology, Bingham Fluid, lubrication, hydrostatic bearing, power efficiency

This study demonstrates the utility of estimating the volume fraction of air in hydraulic oil by measuring the effective bulk modulus of the oil. In this paper, we propose a method for measuring and calculating the effective bulk modulus and volume fraction of air in oil and report experiments that show the validity of the method by comparing with the results measured by another method. Our results clarify that the volume fraction of air in oil can be determined by measuring the effective bulk modulus of the oil.

The shaft counterface of a radial shaft seals is usually plunge ground. With the aim to reduce costs and production
times, many companies try to use new and alternative manufacturing processes for that task. For example, belt
grinding and superfinishing methods are frequently considered and used. Result of these often-unreflecting
changes of the manufacturing methods, is often leakage and increased wear of the sealing components as well as
other related problems. Because, there is only little information about the functional behaviour of this types of
surface finishes in terms of sealing applications, an experimental investigation has been carried out. This paper
presents the results of these experiments.

The performance requirements of multiple sealing systems for reciprocating movements are continuously
increasing with friction, wear and service time being key performance criteria. The new concept, presented in
this paper, is about adjusting lubrication conditions of all single sealing elements within a sealing system so the
load on each element can be reduced and the performance in terms of friction-wear-lifetime can be optimized.
This paper describes the dilemma in terms of optimizing the performance of the primary and secondary seal and
brings up a new seal concept, where the risk of leakage of lubricant is balanced to ensuring performance of the
primary seal and the extended life of the secondary seal.

In this paper the optimization of the spool and housing geometry in a small hydraulic switching valve to enable
the reduction of the axial flow forces to a minimum value is described. Non-optimized valve geometry is usually
the main cause for many problems related to response time, actuation force and energy consumption. To
overcome these limitations we have done a thorough numerical and experimental analysis focused on fluid flow
forces. The results show that the axial flow forces can be reduced significantly just by modifying the geometry of
the valve spool and housing. Thus the valve dynamic characteristics can be significantly improved.

In automatic and dual clutch transmissions, electromagnetic solenoids and valves are required, which have high
requirements for the magnetic force profile and in particular on the magnetic force hysteresis. While there are
rising numbers of gears and shifting operations in the transmission, these parameters help to increase the
efficiency of the whole transmission and consequently lead to a reduction of fuel consumption and emissions.
The aim of the development was to increase the power density of such solenoids, by further minimization of the
magnetic force hysteresis and by setting an economic benchmark. Furthermore, the goal was to develop a
flexible standardization of these components, which enables an easy adaption to various customer requirements
while offering a cost efficient production on a multi-product line.

Water hydraulic proportional control valves are a novel fluid control device using water as the working fluid. They are very hygienic and eco-compatible, permit high-output control, and have applications in many industries. Previously, the authors expressed its characteristics as a third-order transfer function including a compensation circuit (with spool displacement as a control parameter), solenoid, and pilot valve, and examined the effects of design parameters on frequency characteristics, step response, and system stability. Here, its characteristics are examined in the non-linear region by introducing the non-linearity of the control apertures and damping orifice. The results demonstrate the feasibility of applying a linear model in this region.

LiView® is an innovative stroke transducer for hydraulic cylinders, that is based on the electrical measurement of
the cylinder structure in order to gain information on the piston absolute position and speed. In our paper we
present the main characteristics of the LiView® product, the achieved results in the last two years of
development and we discuss the performance of the system as measured throughout the many test campaigns run
both at cylinder and machine level in the first target customer applications. Moreover, the implications deriving
by the use of this technology on hydraulic systems are discussed, showing its disruptive potential for future
machines.

The article describes ways to adapt the method of characteristics to solving the problem of pressure pulsation
calculation of a high-pressure plunger water pump considering a complex pipeline network using a CAE
software “SimulationX”. The objective of this adaptation is to increase the stability of the numerical solution and
reduce the calculation time. To verify the accuracy of the simulation, the pressure pulsations were compared
with pulsations in various parts of a real complex pipeline. As a result, a compromise between accuracy and
speed of calculations was achieved, which improves the process of pump development.

The necessity for greener, flexible and more efficient equipment has led OEMs and manufacturers to create
intelligent fluid power systems. The complexity of the design of these integrated solutions, involving many fields
of expertise, provides significant challenges. Control Specialists and system designers have their own knowledge
domains so there is an increasing need to use an integrated simulation platform so they can work together.
Hybrid modelling methods of mechatronics software, integrating equation- or model-based modelling and datamapping
from test results– known as Machine Knowledge Management – have many benefits. By combining
these fields of expertise using co-simulation between software and hardware, control specialists and application
experts will be properly integrated in the design and analysis process.

In this paper, a real-time measurement system of power of incompressible unsteady laminar flow in a pipe using
a Kalman filter is studied and condition for successfully performing the real-time measurement is discussed
focused on the number of element of a pipeline model used for the Kalman filter. The optimized finite element
model of pipeline dynamics is used as a plant model of the Kalman filter. The number of element for finite
approximation may influence on accuracy of the approximation. Large enough number of element to approximate
pipeline dynamics may increase real-time computational task of the Kalman filter. In this paper, the optimized
finite element model integrated with the Kalman filter is briefly introduced. The Kalman filter with the optimized
finite element model is installed in a real-time computing system. Turnaround time of the Kalman filter is measured
for various numbers of element. The turnaround time is a key factor to determine sampling time of the real-time
measurement system.

The movement of a vehicle is determined by the torque acting at the wheel. With the speed-controlled engine in
mobile machines, the torque characteristics at the wheel are determined by the transmission. Traditionally, this is
realized with the inherent mechanic-hydraulic torque behaviour of the components, like a torque converter or an
axial piston pump. The disadvantage of this approach is the missing flexibility, resulting in trade-offs like low
fuel efficiency or high effort for the realization of control functions. In contrast, the ongoing electronification of
mobile machines is the enabler for a new, much more flexible technological approach for hydrostatic drive
trains: Torque Control.

Pneumatic components and systems are usually considered to be rather unpleasant according to their acoustic appearance especially in the area of industrial large-scale production plants. Within these applications the major part of the noise emission coincides with the outlet ports of valves where the working medium is depressurized. However, former research and development have yield constructive measures and components as mufflers reducing the absolute magnitude of the measurable sound level to a tolerable range. Regulations and legal requirements might thus be satisfied, yet the subjective perception of the sound still tends to be labeled as uncomfortable or even unbearable. These aspects are not considered within the typical metrics of the sound pressure or power level. In order to achieve objective comparisons and an absolute classification of the sound perception psychoacoustic analysis might be adduced. In this study, the correlation between fluidic and psychoacoustic parameters is investigated. The differences according to the sharpness and loudness during operation of a valve are analysed and a methodology on a possible interpretation and evaluation of the psychoacoustics is given. In detail, the dependency of pressure drop, magnitude of the volume flow through a switching valve with standard exhaust muffler on the noise characteristics is presented. Due to presented results, an enhancement of the models was required and will be discussed in this paper correlating the sharpness to the level of perceptible noise. As a conclusion, the investigation posts a proposal for a psychoacoustic benchmark of pneumatic valves leading to an advanced objective and more suitable way of evaluating noise emissions. Hence, nuanced optimization measures in early phases of development are possible.

This paper presents the Festo Motion Terminal, a new programmable valve terminal, and its technical concept. On this basis, a new type of pneumatic motion control is developed. Two main features – electronic controllable motion and energy-efficiency – are addressed that enhance pneumatic drives from sole mechanic components towards a mechatronic system. The control is an adaptive open-loop control which uses an estimated position and velocity signal of the piston. Cost-efficient integrated components and software-based functionality make this concept economic as well as flexible – essential attributes for Industry 4.0.

Pneumatic pressure boosters are widely applied in handling systems to increase the network pressure. Although they may enable a considerable energy saving for the entire pneumatic system, there is still a large potential for performance improvement. However, the boosting technologies in other domains, as the electrical DC-to-DC converters, present high efficiency. In the given study transferability of electrical DC-to-DC converters into pneumatics was investigated and the potentials of new circuits were researched. Based on the lumped parameters simulation results the most prospective concepts were identified using the three criteria: maximal pressure gain, exergy efficiency, and mass flow rate. The prototypes were implemented on a test rig to verify the simulation results and to compare them with each other.

Pneumatic systems are widespread whenever linear motion between two endpoints is required. However, mainly due to friction forces, motion control is difficult. This paper explores a different solution, based on a linear peristaltic principle, to overcome this problem. The pneumatic actuator proposed has several potential advantages over conventional ones: long strokes require little added cost, curved motion profiles are possible and friction force at low velocities presents better characteristics than the ones of conventional actuators. This paper presents a preliminary study of elementary experimental characteristics of the proposed solution. It is shown that no stick slip occurs at low velocities, whilst maintaining force capabilities similar to those of conventional actuators.

Edge welded metal bellows accumulators are the cutting edge of hydro-pneumatic accumulators. Compared with
other designs such as diaphragm-, bladder- or piston accumulators the gas chamber is usually hermetically sealed
and the metallic barrier between gas and fluid side shows no permeation. This design is maintenance free and
keeps its performance for the whole service live. They have extraordinary media compatibility and an extremely
wide operational temperature range.
HYDACs newest design is mounted on a jet engine. It withstands very high external loads such as vibrations,
shocks and fire. One special feature is an indicator which allows checking the integrity of the metal bellows
without having a sealed component.

This paper contributes to the topic of modelling noise generation and propagation in hydraulic pumps,
particularly focusing on the external gear pumps. By using proper methodologies for the fluid, structure, and air
domains, the model proposed in this study can predict the resultant noise emissions coming from the interactions
between these three domains. Two cases of numerical simulations were performed, considering a different
complexity for reproducing the pump mounting conditions. For validation purposes, noise measurements were
taken in a semi-anechoic chamber on a commercial unit. The effects of the mounting situation on the overall
emitted noise as well as the level of the agreements between simulation and experiments are discussed.

Driving signals of electromechanical control valves require a well dosed dynamic excitation to reduce hysteresis
and to optimise dynamics. Nevertheless, a knowledge based signal definition and parameterisation is rarely
possible. The paper attempts to close this knowledge gap by analysing the valve’s dynamics with commonly
used signals and control schemes. Hence, parameter estimation rules for adapting given parameters for one
signal form to another are deduced. Finally, experimental validation of the findings is carried out by comparison
of the dynamics of a customary valve driven by the different control signals. The paper concludes with
recommendations for dither signal parameterisation.

Pressure pulsations are caused by the flow ripples from a positive displacement hydraulic pump. They are
transmitted throughout fluid power equipment and cause unwanted excitations of the mechanical parts. In many
practical applications, a Helmholtz type hydraulic silencer may be used to attenuate such pulsations. It is the
preferred solution on account of its simple structure and high attenuation performance. However the distinctive
drawback of this silencer is that it is effective only within a narrow range of the attenuating frequency. Therefore,
the silencer is only suitable for use in hydraulic systems, running at constant pump rotational speeds. The
purpose of this research is to develop a novel silencer for hydraulic systems that have a fixed displacement pump
driven at variable rotational speeds. First, a mechanism for adjusting the resonant frequency has been proposed.
This works by changing the volume of the silencer. Secondly, a prototype of the novel silencer was designed
using a new distributed parameter system model, in which the vessel volume was modelled as an annular fluid
line. Finally, the attenuation characteristics of the prototype silencer were verified by measuring the transmission
loss under various conditions, and comparing them with the calculated results.

Predefined tribological systems enable the designer of hydrostatic pumps and motors to leave the domain of
mixed friction contacts and obtain a new way of design. The locations of force conduction and gap sealings
evolve from incalculable subsystems into machine elements with predictable and computable properties.
The method is displayed and validated by the example of the RAC (radial piston machine) development and
leads to a novel concept for an axial piston pump and motor that promises a favourable efficiency chart and
excellent start-stop-properties (patent pending).

Continuously increasing demands for more powerful and more efficient hydraulic machines lead to a rising
complexity of these systems. Using model-based development methods is one approach to face this
challenge. This implies, that the entire development process, from the definition of requirements through to
the design, commissioning and operation of the system is supported by physical models. In this paper, an
overview about the enhancements arising from model-based engineering methods is presented. Therefore,
first methods focusing on the design/commissioning phase, which are already used within industrial
applications are presented. Afterwards, currently developed techniques aiming on the operation phase of a
system, which are enabled through the upcoming digitalization, are considered.

This article describes the analysis and selection of an electrohydraulic pump actuator by means of simulations in
order to optimize operation for any given hydraulic system. The focus is on developing a multidisciplinary
method of analysis. This involves interlinking various submodels such as the electric motor model, pump model
and cost model with a system model. With the help of this method, a large number of designs can be analyzed
automatically for the purpose of assessing the behaviour of the overall system. This delivers a preferred design
variant tailored to the customer’s requirements.

This paper elaborates on the use of virtual engineering methods such as Computational Fluid Dynamics (CFD), Finite Element Method (FEM) and system simulation to significantly improve the performance of hydraulic valves. The different simulation methods are used in conjunction to tackle the typical conflicts of goals in hydraulic engineering (e.g. pressure resistance vs. pressure drop). The approach is illustrated and the results are shown in two hydraulic valve engineering projects.

A significant part of the costs of a pneumatic motion in a machine is caused by commissioning. Today every cylinder chamber needs to be connected by tube to the exactly right port of the valve terminal. In this paper a new concept for commissioning pneumatic systems is presented, where the tubes can be plugged in any arbitrary port of the valve terminal. So the commissioning can be fastened – and money can be saved. The concept bases on the Festo Motion Terminal, a new valve terminal whose valve slices can exercise different valve functions. The functionality change is made only by software. This versatility can be used for the automated commissioning.

In this article, we present a new concept of an active air spring, which can apply pressure and tension forces
independently of its deflection. The active strut mitigates body oscillations and improves the driving comfort
making it attractive for autonomous driving to avoid motion sickness. The model of the active air spring system
and the controller design are described. Furthermore, the suitability of the actuator concept for use in an active
chassis is shown. Finally, we show results of hardware-in-the-loop simulations.

In automated production systems handling is a key technology. Especially for gripping and clamping of
workpieces, vacuum automation plays an essential role in all industry segments. Core part of a vacuum gripping
system is the vacuum generation. Pneumatically driven vacuum generators are widespread in the handling
technology. Due to the technological development there are also new tasks and challenges, because in future
applications there is a trend that compressed air will hardly be available. In this paper it is presented, how
electrically driven vacuum generators can increase the energy efficiency of mobile handling systems and also in
addition to that can influence new forms of work, like human-robot collaboration.

Nowadays, assisted cough devices are widely used in airway mucus clearance for patients who cannot cough
autonomously. However, these devices use an open loop system where the inspiration pressure and time cannot
be adapted to each other, which may cause over or under-inflation. In this paper, a new simulated cough device
based on pneumatic system is presented. Moreover, a pressure-time adaptive algorithm is proposed to settle the
mismatching problem of inspiration pressure and time. Both simulation and experimental studies are conducted
to estimate the applicability of this algorithm for different compliance in a simulated lung. This paper provides a
constructive suggestion for the development of airway clearance technologies.

Bi-stable latching valves are an energy-efficient alternative to mono-stable switching valves especially in applications of process technology requiring low switching frequencies. However, the bi-stability of such valves may be disadvantageous, since external forces can change the valve state randomly without being noticed by the controller. Condition monitoring by using position estimation method enables a valve state determination and thus, safe cost- and energy-efficient bi-stable valves as alternative to mono-stable switching valves.
The paper shows an implementation of a periodic determination of the valve’s state into a cost-efficient electronics for commercial use. Differential inductance method serves as position estimation method, which requires only a voltage and current measurement. Different methods for its calculation are performed and investigated in a realistic environment by using a fluid operated valve.

Modern hydraulic systems of mobile machines are requiring components with new control structures, in order to be compatible with the modern networks of the future. The new generation of electro-mechanic valve actuation technology of Sonceboz is presented in this paper. Compared to the previous actuator, the performance has increased significantly. Moreover, the new control concept enables a wide range of connectivity and on-board diagnostic features. The result is a high innovative valve actuation system with online diagnostic functions that can operate in a network with decentralized intelligence. Therefore, supporting hydraulic valve manufactures to meet the challenges for the highly connected systems of tomorrow.

The presentation will introduce special hydraulic fluids, with which fluid technology solutions for complex
requirements, especially exceptional stresses, boundary lubrication, can be offered.
Newly developed hydraulic fluids for high-pressure operations are presented, which will meet the increased
requirements of redesigned pump tests and test field trials. In this case the respective material combination and
the additivation which is adjusted to the pressure and temperature level, plays a decisive role.
Moreover special hydraulic fluids, latest application-specifically adjusted development trends and a short
overview of the main base oil and additive trends are mentioned.

Hydraulic cylinders are some of the hydraulic components which convert the energy into force and / or movement at the end of the hydraulic circuit. Side loads can occur, which must be absorbed by guide elements. A simplified FEM-based calculation method and test methods of plastic guide rings are described, depending on various parameters (material, deflection, angular misalignment, geometrical conditions, etc.). For the product developers, material-specific prognosis of the guide elements behaviour are possible, regarding stresses, strains and load-bearing capacity of the guide elements, considering the specific dimensions and general conditions, due to a company-internal, parameterized FEM tool. In consequence of an optimized design, the number or the width of the guide elements in a cylinder can possibly be reduced, the resulting advantage could be a shorter length of the cylinder components and corresponding cost reduction.

Whenever decision makers want to follow the trend towards “all-electric” machines, but still need to maintain the major advantages of hydraulic drives, electro hydrostatic actuators (EHA) have become the technology of choice for industrial applications. In an EHA, a variable speed electric motor drives a displacement pump which is directly coupled to the actuator, namely a cylinder. After proofing the functionality of this concept in many commercial applications, current developments are targeting features and levels of efficiency that will even outperform the electro mechanical state of the art. Adaptive electro hydrostatic actuators will finally be the benchmark in terms of compactness, ease of use and energy efficiency for many application classes. This paper presents two different implementations for variable pitch EHAs and a mobile device for EHA fluid management and service.

To reduce cycle times, hydraulic drives become consciously more dynamic, what consequently leads to higher fluid exchange rates. On the part of the pressure supply no effort is too big for the design engineers. The return pipe to the tank is, however, often still calculated with rough formulas. This can lead to damages to the plant by cavitation, water hammers and diesel effects and is no longer up-to-date.
On investigating water hammer events in tank-pipes it becomes obvious that an examination with simple rough calculations is not leading to the desired results. Too many factors must be considered at the calculation of water hammer. Fortunately, nowadays the numeric simulation can calculate the pressure gradient and the pressure am-plitude of a water hammer in very good approximation. Thus, by means of simulation a basic understanding of the problem in the tank pipe can be achieved.
In this contribution the boundary conditions which lead to the emergence of a water hammer after cavitation are introduced. Calculation examples explain the differences of water hammers in drives with HLP fluid and with HFC fluid. By the combination of the simulation results to nomograms, a practice-fit tool is introduced, which can be used to assess the water hammer vulnerability of a drive already during the project planning. The presentation of possible constructive remedial measures completes this contribution.

This paper presents an alternative design approach of electrohydraulic safety manifolds for use in quick-closing
actuators. Setting off from the common 2oo3 voting architecture, a separation of flow paths produces a new
solution employing six solenoid-operated 2/2-way poppet valves with electrical coupling. The technical
discussion exhibits various advantages, such as improved reliability, both from a systematic and from a
probabilistic point of view. It is shown that the new 2oo3plus system beats common other structures with regard
to the safety metrics according to IEC 61508.

During the working stroke of hydraulic cylinder drives unexpected and unwanted resonances in attached pipes are often unavoidable. A main reason is the continuous change of the system's natural frequency because of variable piston and cylinder positions. An analytical investigation of variable resonance situations is difficult since geometric boundary conditions like e.g. diameters and lengths of pipes/cylinders as well as nonlinear effects like e.g. the fluid's compressibility or a viscous-elastic tube expansion must be considered. Typically, concentrated parameter models are used for cylinder drive simulations, though such models are not capable to represent the exact influence of variable cylinder chamber volumes on the resonance situation. This publication presents a new approach that realizes a variable cylinder chamber volume or length in combination with a advanced distributed parameter approach. With theoretical fundamental investigations as well as a simplified example it is shown, that by means of the distributed parameter cylinder, it is possible for the first time to analyse the oscillation situation of a cylinder drive during the complete operating cycle.

Although energy efficiency of an Open Center System (OC-System), used widely for excavators, has been improved from the perspective of hydraulic efficiency, total efficiency including the engine has not been taken into account sufficiently. Meanwhile, a Constant Pressure System (CP-System) enabling the engine to be driven optimally is developed but is not accepted in the industry due to complexity of components. Thus in this research, a hybrid system combining an OC-System with a CP-System is proposed enhancing total efficiency. This system is designed for simulation based on the basic theory and the analysis of measurement data. The simulation shows it consumes 30 % less fuel than the conventional OC-System.

Hydraulic load-sensing systems have become state-of-the-art technology for tractors. They combine high energy
efficiency with ease of use and functionality. However, current systems are suitable for comprehensive
machinery management only to a limited degree, particularly if there is a wide variety of different implements.
With electronic load-sensing (e-LS) machine manufacturers are able to individually, actively and dynamically
optimize the hydraulic system in response to various requirements relating to the implement and work process.
Improved productivity and efficiency increase the economic benefit of the machine and new functions allow
automated and monitored workflows for a simplified machine operation.

In the last decades, simulation tools and virtual prototypes were vastly promoted to speed up development
processes. But for complex systems, the modelling and model validation effort is very high, and always some
modelling inaccuracies have to remain due to account for effective cost and computational effort for the
simulations and validation tests. To contribute to the discussion from another point of view, this paper will
present a new approach to speed up development by extreme reduction of hardware iteration time to test changes
of main valve spool geometry according to operator feedback.

Hybridization is frequently applied in order to increase the energy efficiency of off-road and construction
machinery. One such novel energy saving method was proposed for working hydraulics, based on an established
zonal concept for airplanes. The introduced method supplied the power on demand to the actuators, utilising
direct-driven hydraulics in machinery. However, component selection plays a significant role in order to achieve
high efficiency. Therefore, the primary goal is to evaluate the energy efficiency of selected components for the
front hoe of the micro excavator under the digging and levelling cycles. The efficiency of the zonal hydraulic
pre-selected components was evaluated utilising a developed Matlab/Simulink model and energy efficiency
maps.