Hydromechanical Systems Research Articles

Identifying some regularities of the turbulent steady-state plane-parallel motion of incompressible fluid at the entrance length

This paper investigates the structural changes in the turbulent motion of an incompressible fluid in the hydrodynamic entrance region of plane-parallel pressure motion. Movement in pressure hydromechanical systems usually occurs in a turbulent regime. Studying the patterns of changes in hydrodynamic parameters under conditions of stationary turbulent pressure motion in the inlet region is a very urgent task. The study was carried out on the basis of boundary layer equations. Taking into account the dependence of changes in the kinematic viscosity coefficient that occur between layers of fluid, a boundary value problem was formed. Analytical solutions have been obtained that make it possible to obtain patterns of changes in velocity and pressure in any effective flow section. Based on the general conclusions of the study, solutions were found for two cases: a) the velocity of the fluid entering the cylindrical pipe is constant; b) the velocity of the incoming fluid has a parabolic distribution. For these cases, using computer analysis of the data obtained, general graphs of velocity changes were constructed in various sections along the hydrodynamic entrance region. These graphs, which display the change in velocity along the entire length of the inlet, make it possible to obtain the velocity of fluid movement at any point along the inlet length and estimate the length of the transition zone. The results obtained are among the least studied issues of classical fluid mechanics and are of important theoretical interest. The results obtained are applicable for the correct construction of the hydrodynamic entrance region of machinery. A calculation formula has been obtained to determine the length of the hydrodynamic inlet region

Main approaches and features of the design of aircraft hydro-mechanical control systems

Main approaches and features of the design of aircraft hydro-mechanical control systems

EFFECT OF CARRIER FLUID VISCOSITY AND PARTICLE CONCENTRATION ON STABILITY OF MAGNETORHEOLOGICAL FLUID

Magnetorheological fluids (MRFs) are multiphase smart fluids comprising micro-sized magnetic particles suspended in nonmagnetic carrier fluid. Dispersed particles get polarized and form chains along the magnetic field lines when MRF is exposed to an external magnetic field. It further increases the apparent viscosity. Such rheological characteristics encourage its use in hydro-mechanical systems such as damper, clutch, and brake. These systems become semi-active by using MRF instead of Newtonian oils. The biggest hurdle in rheological response is the sedimentation of particles in MRF. Due to the large density difference between carrier fluid and magnetic particles, the dispersed phase settles and separates from carrier fluid. Numerous studies have been reported on the application of different additives to reduce sedimentation. In the present work, MRF sedimentation is measured using an induction-based setup. The sedimentation index, which is used for quantification of settling, is obtained from the experimental particle settling data. Further, the experimental sedimentation index is used to study the effect of dispersed phase concentration on the stability of magnetorheological fluid. The concentration of the dispersed phase varies from 10 to 25 vol%. It is inferred that increase in the concentration of the dispersion phase increases the stability of MRF.

Application of Deep Reinforcement Learning Control of an Inverted Hydraulic Pendulum

Deep reinforcement learning (RL) control is an emerging branch of machine learning focusing on data-driven solutions to complex nonlinear optimal control problems by trial-and-error learning. This study aims to apply deep reinforcement learning control to a hydromechanical system. The investigated system is an inverted pendulum on a cart with a hydraulic drive. The focus lies on implementing a comprehensive framework for the deep RL controller, which allows for training a control strategy in simulation and solving the tasks of swinging the pendulum up and balancing it. The RL controller can solve these challenges successfully; therefore, reinforcement learning presents a possibility for novel data-driven control approaches for hydromechanical systems.

VOLUMETRIC RIGIDITY OF HYDRAULIC SYSTEMS

A hydraulic drive is a set of interacting hydraulic devices that is designed to be ghosted by means of a working fluid under pressure. The main element in hydraulic drives most machines is a power hydraulic cylinder. Hydraulic cylinder refers to volumetric hydraulic devices, since their operating mode is to fill the volume of the working chamber and empty it. The very principle of operation of the hydraulic cylinder is based on the movement of the worker organ (piston, membrane, plunger), under the influence of the energy of the flow fluid or the mechanical energy of external forces (gravity, spring).Depending on the principle of operation of hydraulic cylinders, it can be divided into two groups: one-way hydraulic cylinder, two-acting hydraulic cylinders. To ensure the operation of the hydraulic cylinder, a pump is required, the purpose of which is to convert mechanical energy into the energy of the flow fluid. Studying the stiffness of a hydraulic cylinder can help determine the optimal load that a hydraulic cylinder can withstand, as well as help in choosing the right size of hydraulic cylinder for a particular system. The stiffness of the hydraulic cylinder can be determined by measuring the movement of the hydraulic cylinder as the load increases in a given range. For example, a hydraulic press can be used to increase the load on a hydraulic cylinder to a certain value, and then a measuring tool can be used to determine the movement of the hydraulic cylinder. This data can be recorded on a computer, which can then be used to analyze and calculate the stiffness of the hydraulic cylinder. The stiffness of the hydraulic cylinder can be expressed in newtons per millimeter or other units depending on the specific measurement system. By using various materials (indicated in the literature), the results of studies aimed at determining the reduced volumetric stiffness of high-pressure hoses and the dependence of the reduced volumetric stiffness of the hydraulic cylinder on the change in the volumes of the working cavities in the process of moving its rod are given. Keywords: hydraulic system, volumetric stiffness, hydraulic cylinder, module, hydromechanical systems, hoses, pressure, rod, dynamics.

Methodology of Designing Sealing Systems for Highly Loaded Rotary Machines

Higher parameters of centrifugal machines are constantly required, such as the pressure of the medium to be sealed and the speed of rotation of the shaft. However, as the parameters increase, it becomes more and more difficult to ensure the effectiveness of sealing. In addition, sealing systems affect the overall safety of equipment operation, especially vibration. In order to harmonize the sealing functions and increase the dynamic rigidity of the rotors of centrifugal machines, a method for modeling complex sealing systems has been developed. Non-contact seals are considered as hydrostatic–dynamic bearings that can effectively dampen rotor oscillations. A general approach to the analysis of non-contact seals as automatic control systems and an algorithm for constructing their dynamic characteristics at the design stage were proposed for the first time. Models of “rotor-gap seal”, impulse seal and “rotor–hydraulic face” systems, and seal-supports of a shaftless pump have been studied to assess the effect of these seal systems on the oscillatory characteristics of the rotor. Analytical dependencies are obtained for calculating the dynamic characteristics and stability limits of seals as hydromechanical systems. The directions for improving the safety of operation of critical pumping equipment due to a targeted increase in the rigidity of non-contact seals are determined, which leads to an increase in the vibration resistance of the rotor and the environ-mental safety of centrifugal machines. The paper proposes a method for designing sealing systems based on the configuration of sealing components in order to achieve harmonization between sealing and vibration reliability, taking into account oscillatory processes due to hydrodynamic sealing characteristics.

ГИДРОДИНАМИЧЕСКИЙ АНАЛИЗ ПРОЦЕССОВ ТОПЛИВНЫХ СИСТЕМ ТИПА «COMMON RAIL» В СРЕДЕ ИМИТАЦИОННОГО МОДЕЛИРОВАНИЯ AVL BOOST HYDSIM

The study objective is modeling hydro-dynamic processes occurring in an electro-magnetic diesel fuel injector using AVL Boost Hydsim software package (SP).
 The task to which the paper is devoted is the design of equipment for Common Rail battery injection and fuel atomization systems; description of methods for developing battery fuel systems using Hydsim SP.
 Research methods: numerical simulation of fuel supply based on hydrodynamic dependencies describing the compressible viscous fluid motion in Hydsim software environment.
 Novelty of the work: due to constant tightening of environmental, technical and economic requirements for diesel internal combustion engines (ICE), which directly depend on the perfection of the fuel supply system, there is a need for software that allows engineers to design the appropriate fuel equipment. It is also important to have an effective and comprehensive methodology for working with such software solutions.
 Research results: a model of an electromagnetic fuel injector of a diesel engine is developed, a brief description is given of the methodology for constructing a hydraulic model of the nozzle (in a two-dimensional problem statement) and an analysis of the simulation results obtained.
 Conclusions: AVL Boost Hydsim SP has a number of advantages over its competitors, which can significantly reduce the time spent on the design and implementation of modern fuel equipment, opportunities for dynamic analysis of hydraulic and hydromechanical engine systems appear.

PERFECTION OF FUNDAMENTALS OF MATHEMATICAL METHOD OF DESIGN OF HYDROSYSTEMS OF DRIVE OF TECHNICAL MACHINES

The vast majority of modern research on the study of hydromechanical systems is based on the use of the theory of automatic control and management. One of the main components of technical machines and cells are their drives. Hydraulic drives are often used as power. In general, its functional and operational characteristics have a decisive influence on the properties of hydrodynamic systems and general technical machines. In this regard, close attention is paid to the study of hydraulic power drives. However, the power hydraulic drive of technical machines and units in one form or another necessarily includes both electric and mechanical drives, which turns it into a system of various drive systems. The vast majority of modern research is devoted to the study of hydraulic drives, which are based on spool-type hydraulics, which limits the possibility of using new structural materials in the drive systems of technical machines. Many technical machines and installations, especially in agro-industrial complexes, work in harsh conditions, with high temperatures and dust, low quality of working fluid and other unfavorable characteristics that significantly reduce the reliability of drive systems equipped with hydraulic spool types and quality equipment. At current levels of working pressure in the hydraulic system, the forces and speeds of the working bodies of technical machines and units of the agro-industrial complex, the compressibility of the working fluid and the flexibility of the hydraulic elements of the drive system are determined, become noticeable, which requires further improvement of theory and methodology. The theoretical basis of the method of calculating the equipment drive system has been improved on the basis of the complex characteristics of the hydraulic system introduced by the author - the resulting volumetric stiffness is used to simplify the drive modeling process by increasing the accuracy of calculation and analysis of its results.

General Approach to Modeling of Non-Contact Seals and Their Effect on the Dynamics of a Centrifugal Machine Rotor

There is a constant demand for higher equipment parameters, such as pressure of a sealing medium and shaft rotation speed. However, as the parameters rise it becomes more difficult to ensure hermetization efficiency. Moreover, sealing systems affect the overall operational safety of the equipment, especially vibratory. Non-contact seals are considered as hydrostatodynamic supports that can effectively damp rotor oscillations. Models of an impulse and a groove seals, models of rotor-seals system and rotor-auto-unloading system, model of a shaftless pump are studied to evaluate an effect of these sealing systems on oscillatory characteristics of rotor. Analytical dependencies for computation the dynamic characteristics of impulse seals, hydromechanical systems rotor-seals and rotor-auto-unloading, as well as shaftless pumps are obtained. These dependencies describe the radial-angular vibrations of a centrifugal machine rotor in seals-supports. Equations for computation the amplitude-frequency characteristics are given. The directions of improving the оperational safety of critical pumping equipment by purposefully increasing the rigidity of non-contact seals that leads to higher rotor vibration stability have been determined.

Synchronization in multi-motor hydromechanical systems

Introduction. The paper submits the analysis of existing design solutions of flow dividers used to synchronize hydraulic drives of working bodies of technological and mobile machines. The market demands for multithreaded throttle flow dividers without valves with the controlled division ratio, such as multi-axle vehicle chassis, are identified. The objective of the work was to analyze the possibility and rationale for developing a throttle four-way flow divider without valves with sensing elements of the Venturi tube type. The solution should provide the synchronicity of movement (rotation) of more than three working bodies of technological and mobile machines.Materials and Methods. A patent search for the designs of hydraulic flow dividers is carried out, and systems that require the division of the hydraulic fluid flow into more than two executive bodies are considered. An upgrade option, which allows dividing the flow into four branches, is proposed for the design of a three-channel throttle flow divider without valves.Results. The urgency of developing a multithreaded throttle flow divider without valves for application in industrial and mobile machines is validated. Two types of four-flow dividers are considered, their weaknesses are indicated. It is noted that the development of a multithreaded throttle flow divider based on the designs created in 1989 and 1991 will reduce the number of hydraulic pumps and get rid of the series connection of double-flow dividers. In this way, it is possible to reduce pressure losses in the hydraulic system and implement adaptive control of hydraulic motors of multi-motor mobile machines. The possibility to obtain a divider/combiner into four flows by adding an outlet chamber connected to the membrane chamber through a channel entering the Venturi nozzle on the basis of a three-flow throttle divider is shown. The principle of operation of such equipment is described.Discussion and Conclusions. The principles of construction of throttle flow dividers without valves are considered. An upgrade option is proposed to increase the number of division channels from three to four. However, to validate the operability of this design, a numerical analysis of the various modes of operation of the divider is required — calculation of the reduced volumetric stiffness of its working cavities. The information obtained can be used to modernize the hydraulic units of technological and mobile machines, increase their reliability, manufacturability, and efficiency. The issues that need to be solved in further research are identified.

Justification of the hydro-mechanical systems operating modes, used for restoring accumulation capacity of tailings storages

The paper describes the ways to extend the service life of tailings storage facilities by restoring their accumulation capacity. Analysis of the state-of-the-art experience in tailings management is provided. Restoring is carried out due to the following: storing of waste as paste-like slurry; raising embankment; intensifying wastewater treatment process in ponds by means of coagulation agents; selection of adequate alluviation maps mode; specifying parameters of surface and underwater alluvial beaches; implementing the separate storage of solid-phase fractions; preliminary pulp clarification in alluviation maps before supplying it to the pond. Due to the long length of the hydrotransport lines, the use of paste thickeners in the mining and processing plants of Kryvbas is impossible. These technologies are implemented at new storage facilities where waste is placed in the first tier. The aim of this study is to determine and substantiate parameters of hydro-mechanical systems during the operation of tailing facilities with temporary clarifiers. The study for the first time established relationship between the temporary pond operation time. There are such parameters as concentration and consumption of slurry, initial depth of the pond filling, barrier dam height and the length of alluvial front.

Численное исследование влияния толщины стенки трубопровода на собственные динамические параметры гидромеханической системы

This article is devoted to solving the problem of noise and vibration in complex pipelines of hydromechanical systems. In the study, the first ten frequencies of natural oscillations are calculated for sections of the pipeline system filled with water with outer diameters of 60, 70, 102 mm and various thicknesses of the pipeline wall. It is determined that for all the investigated diameters, a decrease in the natural vibration frequencies for all modes of natural vibrations with an increase in the thickness of the pipeline wall is characteristic. Thus, the assumption is confirmed that an increase in the rigidity of the pipeline reduces the likelihood of oscillations in the pipeline. It is concluded that in straight sections the pipeline system with diameters up to 102 mm behaves only as a mechanical system.

HYDROSTATIC GENERATOR OF NON-PERIODIC PRESSURE IMPULSES FOR TESTING TECHNICAL PRODUCTS

The article reviews the possibility of using the hydrostatic generators of oscillators with nonlinear power elements (elastic shells) as part of the structures of various test benches in the field of mechanical tests for vibration strength and vibration resistance, as well as when testing with external and internal pressure. The hydrostatic generator of non-periodic pressure impulses for engineering products testing is a new patented technical solution in the field of testing machines. The ratios of the angular velocities of the shafts, which provides the movement of the operating fluid into the actuator of the test bench in the form of a non-periodic function and with impulses varying in amplitude in a random manner were obtained. It makes a continuous and non-repetitive sequence of pressure impulses and corresponds to the operation of the tested objects in real conditions. The random nature of the amplitudes settings is provided by signals controlled from electric generators through controlled hydraulic valves. The development of a hydrostatic generator with a power element in the form of an elastic shell is represented by a hydromechanical diagram of a generator of non-periodic pressure impulses with corresponding kinematic and dynamic dependencies. In addition, there were developed three hydro-mechanical systems with the use of a new hydrostatic generator for engineering products testing both for mechanical random vibration and for testing the external and internal pressure of engineering objects that operate in such conditions. The result of the research is the expansion of the range of systems and methods for the test processes implementation under random non-periodic force effects on various engineering objects.

Assessment of the switching time and fluid type influence on the transient quality in hydro-mechanical systems

The number of transients in hydro-mechanical power transmissions accounts for a significant portion of the total operating time and has a significant impact on drive economy. The quality of the transients largely depends on their duration and the type of working fluid used. The purpose of the work is to analyze the transients in the hydro-mechanical system, taking into account the effect of the duration of switching processes and the type of working fluid used. Determination of transient parameters in the hydro-mechanical power transmission was performed on the basis of mathematical dependences describing the switching process of two torque converters depending on the duration of the filling and emptying process and the influence of the type of working fluid used. Analysis of the calculated characteristics of transients in hydromechanical power transmissions showed that the main factor in the switching of torque converters, is the combination of filling and emptying processes, depending on the type of working fluid used. The obtained results give grounds to propose recommendations on coordination of filling and emptying processes in order to increase the efficiency of the hydromechanical drive.

ON THE FORMATION OF DYNAMIC PROPERTIES OF PNEUMATIC AND HYDROMECHANICAL SYSTEMS

The article presents a brief analysis of the results of the work of the scientific school of the Academician of the Russian Academy of Sciences V.P. Shorin on the creation of methods and means for eliminating oscillations in pipeline chains of pneumatic and hydraulic systems. The principles of construction and possible structures of dampers for forced vibrations of the working medium, as well as criteria and methods for assessing the effectiveness of the dampers are stated. The possibility of using vibration dampers as correcting devices to ensure the stability of hydromechanical control systems and equalize the frequency characteristics of measuring pipeline circuits is shown.

Вирішення сучасних проблем динаміки технічних систем

This paper overviews the main results obtained over the past few years at the Department of Hydromechanical Systems Dynamics and Vibration Protection Systems, Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine, in the solution of current problems in the dynamics of liquid-propellant rocket engines (LPREs), liquid-propellant launch vehicle pogo stability, vibration protection system dynamics, the gas dynamics of aircraft gas turbine engine components, and the dynamics of hydraulic systems with cavitating elements. These results are as follows. A mathematical model of LPRE pump dynamics was developed. The model complements a hydrodynamic model of LPRE cavitating pumps by allowing a mathematical simulation of choking regimes. An approach was developed to the construction of a nonlinear mathematical model of LPRE hydraulic line filling. The approach allows one to automatically change, if necessary, the finite element partitioning scheme of a hydraulic line in the process of its filling during LPRE startup calculations. An investigation was conducted into the startup dynamics of a multiengine liquid-propellant propulsion system that consists of four staged-combustion oxidizer-rich LPRDs with account for the possibility of their nonsimultaneous startup. The maximum values of oxidizer and fuel pressure surges and undershoots at the liquid-propellant jet system (LPJS) inlet at an engine spartup and shutdown were determined and used in determining the LPJS operability at the startup and shutdown of the RD861K sustainer engine. The pogo stability of the Cyclone-4M launch vehicle was analyzed analytically using Nyquist’s criterion. A numerical approach was developed to characterizing acoustic oscillations of the combustion products in annular rocket combustion chambers with account for the configuration features of the fire space and the variation of the physical properties of the gaseous medium with the axial length of the chamber. A prototype vibration protection system was developed and made, and its dynamic tests confirmed its high efficiency in damping impact and harmonic disturbances. Approaches were developed to the aerodynamic improvement of aircraft gas turbine engine components. Topical problems in solids grinding in a liquid medium with the use a cavitation pulse technology were solved.

Self-Oscillations of The Free Turbine Speed in Testing Turboshaft Engine with Hydraulic Dynamometer

Self-oscillations are one of the common problems in the complex automatic system, that can occur due to the features of the workflow and the design of the governor. The development of digital control systems has made it possible to damp self-oscillations by applying complex control laws. However, for hydromechanical systems, such way is unacceptable due to the design complexity and the governor cost. The objective of this work is to determine the parameters of the hydromechanical free turbine speed controller, ensuring the absence of self-oscillations during ground tests of the turboshaft engine with a hydraulic dynamometer. The TV3-117VM engine (Ukraine) with the NR-3VM regulator pump (Ukraine) was selected as the object of the study. However, self-oscillations can also occur in any modifications of the TV3-117 engine with any NR-3 regulator pump. The results of the research may be of interest to engineers and scientists who investigate the dynamics of automatic control systems for similar engines. The paper analyses the nonlinear features of the empirical characteristics of the FTSC leading to self-oscillations of the engine speed. The authors propose the mathematical model of the automatic control system dynamics, which takes into account all the features of the engine and regulator pump. It is shown that the load characteristics of the water brake and the helicopter main rotor can differ significantly. Research of the dynamic characteristics of the TV3-117VM engine was carried out. The analysis showed a good agreement between the calculation results and the field test results, and made it possible to determine the parameters of the controller, which lead to self-oscillations during test. Two cases are considered. The first case includes ground tests of the engine with a water brake; the second case—flight tests of the engine as part of the helicopter’s power plant. The data obtained make it possible to develop recommendations for adjusting the hydromechanical governor without testing it on the engine.

АНАЛИТИКО-ЧИСЛЕННЫЙ МЕТОД РАСЧЕТА ГИДРОФРИКЦИОННОГО ГАСИТЕЛЯ КОЛЕБАНИЙ ЭЛЕКТРОПОДВИЖНОГО СОСТАВА

The paper studies the problem of modeling vibrations of a torsion hydro-friction damper of a locomotive with the support of hydrodynamic friction based on the application for a Patent of the Republic of Uzbekistan. The objectives of the authors’ invention are: to improve the reliability and damping capacity of the damper as a whole, with the provision of horizontal and vertical damping of vibrations and shock loads, which is important to increase the speeds of the rail transport; to increase the dynamic factor of the system while regulating the damping capacity by creating an additional friction torque to reduce dynamic load on the cantilever section of the shaft fixed to the bogie frame of the vehicle. It is possible to predict various hydromechanical systems using a similar analytical-numerical method, i.e. to analyze the dynamic functioning of hydraulic and hydro-friction torsiontype vibration dampers for electric rolling stock. Dynamic bench tests were carried out at a depot in Uzbekistan. A torsion type of hydrofriction vibration damper was used for testing an upgraded (new) construction.

Peer review declaration

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing. • Type of peer review: Open • Conference submission management system: s (one page of text) and Papers in English offered for inclusion in the Moscow FAPM-2019 Program should be sent to the Local Organizing Committee. • • The format of files of abstracts and papers is *.docx and *.doc (you also should send the copy in PDF format). An article should be formed as one file and should include: • • 1. A title; • • 2. Information about authors; • • 3. Key words; • • 4. A brief annotation; • • 5. Text of paper; • • 6. A list of references; • • 7. Illustrations and tables should be numbered and titled and be included into the text of paper. All papers and abstracts should be formed due to the rules which you can find on the Moscow FAPM-2019 web-site. All enquiries concerning length of abstracts, papers, registration, accommodation, etc. should be sent to the Organizing Committee preferably by e-mail to FAPM2019@mail.ru The articles should be thoroughly revised and put into shape in according to requirements. The Proceedings will generally revised, therefore, the Organizing Committee keeps the rights for itself to use the special review of any article. In the case reviewers will be specialists of Leading Universities of Russia or aboard. • Number of submissions received: 112 • Number of submissions sent for review: 84 • Number of submissions accepted: 38 • Acceptance Rate (Number of Submissions Accepted / Number of Submissions Received X 100): 45 • Average number of reviews per paper: 2 • Total number of reviewers involved: 18 • Any additional info on review process: First, we send an invitation to take part in our conference to as many potential participants as possible from Russian and foreign scientific and educational institutions. • • We send the resulting abstracts to one of the following sections: • • • Theoretical mechanics • Celestial Mechanics • Mathematical modeling of mechanical systems, stability, traffic control • Hydromechanics • Aerodynamics, ballistics and space flight control • Applied mechanics, theory of oscillations • Problems of optimization, identification and reliability of mechanical and hydromechanical systems • Biomechanics, robotics, mechatronics • Theory of Mechanisms and Mechanics of Machines • Computational mathematics in mechanics • Topical issues of natural sciences • Scientific-methodical and historical questions of mechanics • • Further, the participants must make an oral presentation at the conference. Each section has 1-2 supervisors from among well-known Russian or foreign scientists, who can, after hearing the report, recommend publishing an article on this work. Works must be original and new, not previously published anywhere. Have scientific novelty and relevance. If all these conditions are met, and there is also a recommendation from the supervisor of the section, then we accept the article in order to apply. • Contact person for queries: Barkin Mikhail, Bauman Moscow State Technical University, barkin@bmstu.ru, barkin@yandex.ru

Constrained real-time control of hydromechanical powertrains – methodology and practical application

Axial piston motors and pumps are core components in many hydromechanical systems as for instance the powertrain of wheel loader vehicles. The optimal performance of the individual components as well as the entire powertrain requires a fast and exact control of both the motor’s swivel angle as well as the pressure difference over the pump by means of the currently available information and despite their respective a-priori unknown reference signal generated by the driver with a joystick or gas pedal operation. Therefore, it is essential that the swivel angle and pressure controllers fully exploit the possible dynamics and the constrained resources of the nonlinear swivel angle displacement and the pressure adjustment system, respectively. In this work, a flatness-based feedforward control strategy for the motor’s swivel angle as well as a flatness-based tracking two-degree-of-freedom controller for the pump pressure are proposed. For the realization of the flat feedforward and the tracking controller, a constrained online trajectory generation by means of a nonlinear (switched) state variable filter is designed for each. Therefore, both controllers are capable of considering the relevant state and input constraints in real-time and without relying on an online optimization. The proposed control algorithms are both discussed and their performance is illustrated with measurement data from a wheel loader vehicle.