Читать книгу Hydraulic Fluid Power - Andrea Vacca - Страница 4

1 Chapter 1Figure 1.1 The axial piston pump sketched by A. Ramelli [1].Figure 1.2 The Williams–Janney transmission was based on axial piston design...Figure 1.3 A collage of pictures from historical moments of the fluid power ...Figure 1.4 Hydraulic system of a jet blast deflector.Figure 1.5 Hydraulic circuit with pilot‐controlled sequence valve.Figure 1.6 Hydraulic circuit for moving an actuator.Figure 1.7 Meaning of different types of lines in hydraulic circuits.Figure 1.8 Common symbols for prime movers and mechanical rotary transmissio...Figure 1.9 Common symbols utilized for prime movers and energy conversion un...Figure 1.10 Common symbols utilized for directional and pressure control ele...Figure 1.11 Symbols used for accessory elements and sensors.

2 Chapter 2Figure 2.1 Example of simple hydraulic circuit. The hydraulic fluid can be i...Figure 2.2 Classification of mineral oils according to ISO 6473‐4.Figure 2.3 Classification of fire‐resistant fluids according to ISO 7745....Figure 2.4 Density variation with pressure for three oils (parameters listed...Figure 2.5 Density variation with temperature for three oils (parameters lis...Figure 2.6 Shear stress in a fluid: initial rest condition (a) and (b) after...Figure 2.7 Viscosity of hydraulic fluids as a function of the temperature.Figure 2.8 Qualitative representation of the viscosity index (VI).Figure 2.9 Viscosity as a function of pressure.Figure 2.10 Typical causes of entrained air within the hydraulic fluid: (a) ...Figure 2.11 Equilibrium states for a liquid considering gas solubility.Figure 2.12 Compression of a mixture of liquid and undissolved gas.Figure 2.13 Graphical representation of the dissolved and undissolved air in...Figure 2.14 Solid particles entering the clearances of a hydraulic control v...Figure 2.15 Suction filtration circuit.Figure 2.16 High pressure filtration circuit: (a) application to the whole c...Figure 2.17 Return filtration circuit.Figure 2.18 Offline filtration circuit.Figure 2.19 Typical design of a hydraulic reservoir.

3 Chapter 3Figure 3.1 Basic hydraulic machine.Figure 3.2 Fluid pressure increases with depth.Figure 3.3 Elevation difference in the hydraulic circuit of a mobile applica...Figure 3.4 Flow through a pipe: velocity vector and surface area vector. (a)...Figure 3.5 Actual velocity profile (laminar and turbulent flow) and uniform ...Figure 3.6 Control volume (CV) and bounding control surface (CS).Figure 3.7 Conservation of mass in a hydraulic junction.Figure 3.8 Representation of a hydraulic cylinder during the extension.Figure 3.9 Venturi tube and representation of streamlines.Figure 3.10 Laminar (a) and turbulent (b) velocity profiles in a pipe, with ...Figure 3.11 Example of analysis of major and minor losses in a pipe flow.Figure 3.12 Moody's diagram for the calculation of the friction factor.Figure 3.13 Example of separation region at a flow entrance.Figure 3.14 Resistance across a hydraulic check valve.Figure 3.15 Linear approximation for the hydraulic resistance in turbulent f...Figure 3.16 Graphical representation of flow law (a) and pressure law (b).Figure 3.17 Reference geometry for the analysis of flow forces.

4 Chapter 4Figure 4.1 Flow through a sharp orifice.Figure 4.2 Orifice area for a poppet needle valve. (a) Entire popper valve. ...Figure 4.3 Theoretical and experimental trends of the flow coefficient vs. t...Figure 4.4 Orifice equation plotted in a (p, Q) layer for different area ope...Figure 4.5 Hydraulic symbol of two valves and equivalent orifice networks.Figure 4.6 Orifice in parallel and in series.

5 Chapter 5Figure 5.1 Control volume (CV) and bounding control surface (CS).Figure 5.2 Constant section pipe with uniform velocity profile.Figure 5.3 An orifice connected to upstream and downstream lines is a pure r...Figure 5.4 Impedance model for a hydraulic line. (a) Real system, (b) Lumped...Figure 5.5 Lumped distributive model for a hydraulic line. (a) Real system, ...Figure 5.6 Conceptual representation of using of a hydraulic accumulator for...

6 Chapter 6Figure 6.1 Power flow in a hydraulic system.Figure 6.2 Representation of power flow and input‐output energy parameters i...Figure 6.3 Plunger pump with port selection spool.Figure 6.4 Commutation points for a plunger pump, starting from the bottom l...Figure 6.5 Ideal working cycle of the plunger pump.Figure 6.6 Wobble plate pump (a) and ISO pump symbol (b).Figure 6.7 Displacement chamber volume as a function of the shaft angular po...Figure 6.8 Procedure for assembling a pump symbol. The factors to be conside...Figure 6.9 ISO symbols of the most common pumps.Figure 6.10 Symbol breakdown for a hydraulic motor (top) and ISO symbols of ...Figure 6.11 Displacing cycle of an ideal hydrostatic machine with compressib...Figure 6.12 Examples of external leakage and internal leakage.Figure 6.13 Effect of turbulent losses: (a) pump; (b) motor.Figure 6.14 Incomplete filling.Figure 6.15 Trends for the volumetric losses.Figure 6.16 Trends for the hydraulic-mechanical losses.Figure 6.17 Qualitative representation of volumetric, hydraulic-mechanical, ...Figure 6.18 Qualitative representation of volumetric, hydraulic-mechanical, ...Figure 6.19 Swashplate‐type axial piston machine vertical cross‐section.Figure 6.20 Swashplate‐type axial piston machine horizontal cross‐section.Figure 6.21 Valve plate geometry example for a bidirectional motor.Figure 6.22 Pressures in a swashplate axial piston machine.Figure 6.23 Three lubricating interfaces in swashplate‐type axial piston mac...Figure 6.24 Bent axis‐type axial piston machine.Figure 6.25 Radial piston machine.Figure 6.26 External gear machine: (a) view of the lateral bushing surface f...Figure 6.27 External gear machine lateral bushing.Figure 6.28 Internal gear machine.Figure 6.29 Gerotor cross‐section.Figure 6.30 Vane pump cross‐section.Figure 6.31 Vane pump port flow.Figure 6.32 Single stator vane machine.

7 Chapter 7Figure 7.1 Linear actuator architecture and ISO symbol.Figure 7.2 ISO symbols of various linear actuators.Figure 7.3 Cylinder areas, forces, and pressure. The sign convention for the...Figure 7.4 Definition of resistive and overrunning loads for a hydraulic cyl...Figure 7.5 Schematic for the definition of volumetric efficiency for a hydra...Figure 6 Conceptual cross‐section of a two‐stage single acting telescopic cy...Figure 7 Conceptual cross‐section of a two‐stage double acting telescopic cy...

8 Chapter 8Figure 8.1 Generic parameters of springs used in hydraulic components and, i...Figure 8.2 Possible symbols for a check valve.Figure 8.3 Architectures for a check valve. (a) Poppet‐seat type. (b) Ball‐s...Figure 8.4 Flow–pressure characteristic of a check valve.Figure 8.5 Pilot‐to‐open (a) and pilot‐to‐close (b) check valves.Figure 8.6 Symbol and cross‐section of a shuttle valve. Cross section (a) an...Figure 8.7 ISO symbol and its breakdown for a direct acting pressure relief ...Figure 8.8 Direct acting pressure relief valve, poppet type. (a) Cross secti...Figure 8.9 Steady‐state characteristic of a direct acting pressure relief va...Figure 8.10 Pilot operated pressure relief valve.Figure 8.11 Detailed ISO representation of a pilot operated relief valve (a)...Figure 8.12 Steady‐state characteristic of pressure relief valves: qualitati...Figure 8.13 Direct acting pressure reducing and relieving valve: cross secti...Figure 8.14 Ideal (a) and real operating characteristics (b) of a pressure r...Figure 8.15 Pilot operated pressure reducing valve: cross sectional view (a)...Figure 8.16 ISO representation of a two‐way flow control valve: simplified s...Figure 8.17 Cross‐section of a post‐compensated two‐way flow control.Figure 8.18 Detailed ISO symbol for the valve of Figure 8.17.Figure 8.19 Characteristic of a two‐way pressure compensated valve.Figure 8.20 Examples of variable setting two‐way flow control valves.Figure 8.21 Circuit with a two‐way flow control supplied by a fixed displace...Figure 8.22 Detailed (a) and simplified (b) ISO representations of a three‐w...Figure 8.23 Three‐way flow control valve: cross‐section and equivalent symbo...Figure 8.24 Different solutions for adjustable three‐way flow control valves...Figure 8.25 Circuit with a two‐way flow control supplied by a fixed displace...Figure 8.26 Circuit where the three‐way flow control is also used for accomp...Figure 8.27 Three‐way priority flow control valve.Figure 8.28 ISO symbols used for (a) on/off, (b) discrete position, and (c) ...Figure 8.29 Example of a 4/3 spool directional control valve (a): simplified...Figure 8.30 Orifice connections implemented through spool and bore lands.Figure 8.31 Example of opening area vs. spool position for the meter‐in and ...Figure 8.32 Spool with metering notches to obtain fine regulations: cross se...Figure 8.33 Example of possible neutral configurations of a 3/4 DCV: (a) mot...Figure 8.34 Spool actuation principle for a hydraulic pilot operated 4/3 DCV...Figure 8.35 Solenoid basic architecture and operating principle and ISO symb...Figure 8.36 ISO symbols of a DCV with (a) manual and (b) direct solenoid act...Figure 8.37 ISO schematic of a DCV with hydraulic remote pilot actuation con...Figure 8.38 (a) ISO expanded circuit representing an electro‐hydraulic actua...Figure 8.39 Cross‐section and equivalent schematic of a DCV with manual and ...Figure 8.40 Architecture of a servovalve (flapper/nozzle type).Figure 8.41 Spool lapping around the center positions for servovalves. (a) C...Figure 8.42 Opening area (a) and Flow characteristic (b) of a servovalve as...Figure 8.43 Control mechanism of the servovalve (flapper‐nozzle type): (a) i...Figure 8.44 Use of a servovalve for controlling and actuator. Depending on t...Figure 8.45 Parametrization of the servovalve: (a) cross sectional view; (b)...Figure 8.46 Characteristic curve of a servovalve.Figure 8.47 Simplified schematic for understanding the servovalve characteri...Figure 8.48 Characteristic curve of a servovalve (alternative).Figure 8.49 Characteristic curve of a servovalve with positive lapping (clos...Figure 8.50 Characteristic curve of a servovalve with negative lapping (open...Figure 8.51 Valve open at an intermediate position.Figure 8.52 Linearity error in a spool valve.

9 Chapter 9Figure 9.1 Cross‐section of a spring‐loaded accumulator. The supply port P i...Figure 9.2 Piston‐type gas‐loaded accumulator.Figure 9.3 Diaphragm‐type gas‐loaded accumulator.Figure 9.4 Bladder‐type gas‐loaded accumulator.Figure 9.5 Operating conditions for a bladder accumulator: precharge conditi...Figure 9.6 Simplified circuit for hydraulic brakes.Figure 9.7 Accumulator in a vehicle suspension circuit.Figure 9.8 Use of an accumulator for pulsation dampening.Figure 9.9 Polytropic behavior of the gas inside the accumulator.Figure 9.10 Accumulator for pressure dampening.

10 Chapter 10Figure 10.1 Control variables for a linear (a) and rotary (b) actuators.Figure 10.2 A cylinder compressing material (a), or a rotary actuator drivin...Figure 10.3 Simple example for understanding resistive and overrunning loads...Figure 10.4 Resistive and assistive loads for linear actuators.Figure 10.5 Resistive and assistive loads for motors.

11 Chapter 11Figure 11.1 The basic control concepts involved in the control of a single a...Figure 11.2 Control concepts in case of flow supply. Each architecture is re...Figure 11.3 Control concepts in case of pressure supply. Each architecture i...Figure 11.4 Primary control with fixed (a) or variable displacement flow (b)...Figure 11.5 Metering controls with fixed displacement flow supply: the conce...Figure 11.6 Metering controls with variable displacement flow supply. Advanc...Figure 11.7 Secondary control with flow supply with fixed displacement pump ...Figure 11.8 Primary control with pressure supply circuits using fixed displa...Figure 11.9 Pressure supply of primary control with a variable displacement ...Figure 11.10 Pressure supply, metering controls using fixed displacement pum...Figure 11.11 Pressure supply of metering control with a variable displacemen...Figure 11.12 Pressure supply of secondary controlled circuits. The circuits ...

12 Chapter 12Figure 12.1 Basic illustration of the regeneration concept: (a) standard ext...Figure 12.2 Regeneration achieved using a standard DCV and two external valv...Figure 12.3 Example of spools with regenerative extension. Standard 4/3 DCV ...Figure 12.4 Example of open‐center type spool with regenerative extension po...Figure 12.5 Circuit with automatic selection of the regenerative extension d...Figure 12.6 Characteristics of the automated regenerative circuit of Figure ...Figure 12.7 “On demand” regeneration circuits solenoid actuated.

13 Chapter 13Figure 13.1 General layout for the meter‐in (a) and the meter‐out (b) contro...Figure 13.2 Meter‐in control concept using a fixed (a) and a variable (b) di...Figure 13.3 Control modes for the actuator in the circuits shown in Figure 1...Figure 13.4 Power consumption analysis for the circuits of Figure 13.2 : (a)...Figure 13.5 Meter‐out control concept using a fixed (a) and a variable (b) d...Figure 13.6 Control of the actuator velocity with the circuits in Figure 13....Figure 13.7 Power consumption analysis for the circuits in Figure 13.5 for r...Figure 13.8 Control of the actuator velocity with the circuits in Figure 13....Figure 13.9 Power consumption analysis of the basic meter‐out control circui...Figure 13.10 Summary of the possible meter‐in and meter‐out control situatio...Figure 13.11 Proportional DCV with meter‐in and meter‐out areas and simplifi...Figure 13.12 Different designs of independent metering elements: (a) meterin...Figure 13.13 The loader attachment for a tractor is a typical example of use...Figure 13.14 Anticavitation valve: schematic (a) and real valve characterist...Figure 13.15 Pressurization of return lines for anti‐cavitation function usi...

14 Chapter 14Figure 14.1 Spool (a) and poppet (b) elements achieving a similar functional...Figure 14.2 Pilot operated check valve (a) and equivalent symbol (b).Figure 14.3 Typical circuit utilizing a pilot operated check valve for load ...Figure 14.4 ISO symbol for a counterbalance valve.Figure 14.5 Working principle of a counterbalance valve.Figure 14.6 Typical architecture of a CBV.Figure 14.7 CBV during the check valve operation.Figure 14.8 CBV during the pressure relief operation.Figure 14.9 CBV during the pilot pressure operation.Figure 14.10 Application of CBVs for controlling the motion of a linear actu...Figure 14.11 Steady‐state operation of a counterbalance valve for different ...Figure 14.12 CBV steady state characteristic for different valve settings: (...Figure 14.13 A counterbalance valve can be approximated as a variable orific...Figure 14.14 Different solutions for CBV spring chamber drain: internal drai...Figure 14.15 Operating characteristic of the circuit in Figure 14.10 with ve...

15 Chapter 15Figure 15.1 Principle of operation of bleed‐off (a) and open center (b).Figure 15.2 Typical circuit applying a bleed‐off strategy to control the spe...Figure 15.3 Pressure and flows in the bleed‐off system, for different input ...Figure 15.4 Energy plot for the bleed‐off circuit in Figure 15.2.Figure 15.5 Typical layout of an open center system (a) with detailed view o...Figure 15.6 Pump pressure and flow (a), and area (b) trends for an open cent...Figure 15.7 Influence of load pressure (a) and pump flow (b) on the control ...Figure 15.8 Cross sections (a, b) of an open center valve and equivalent spo...Figure 15.9 Energy plot for the open center circuit in Figure 15.5.Figure 15.10 Basic architecture of a negative flow control system. The pump ...Figure 15.11 Relationship between displacement V _p and pilot pressure p _s in a...Figure 15.12 Pump pressure and flow (a) and area (b) trends for an open cent...Figure 15.13 Detailed view of a possible control concept for negative flow c...Figure 15.14 Actual implementation of the negative flow control for an axial...Figure 15.15 Basic architecture of a positive flow control system. The pump ...Figure 15.16 Relationship between displacement V _p and pilot pressure p _s in a...Figure 15.17 Detailed view of a possible control concept for positive flow c...Figure 15.18 Energy plot for the advanced open center systems.

16 Chapter 16Figure 16.1 Load sensing principle (flow supply, fixed displacement pump) fo...Figure 16.2 Limiting the maximum pressure in the LS system of Figure 16.1: w...Figure 16.3 Energy plot of the LS system in Figure 16.1.Figure 16.4 Flow rate provided to the actuator by the LS system in Figure 16...Figure 16.5 LS system with fixed displacement pump using a 5/3 proportional ...Figure 16.6 5/3 Proportional LS valve architecture, with integrated work‐por...Figure 16.7 LS system with a variable displacement pump: (a) conceptual sche...Figure 16.8 Energy plot of the LS system in Figure 16.7Figure 16.9 Detailed ISO schematic of a variable displacement pump with pres...Figure 16.10 Variable displacement pump with pressure limiter and differenti...Figure 16.11 Detail of the differential pressure limiter during regulation....Figure 16.12 Load sensing system using independent metering elements.Figure 16.13 Circuit implementing the electronic LS principle.

17 Chapter 17Figure 17.1 Constant pressure system using a variable displacement pump.Figure 17.2 Pump pressure (a), flow, and area trends (b) for a constant pres...Figure 17.3 Influence of the load on the actuator flow in a constant pressur...Figure 17.4 Energy plot for the constant pressure circuit of Figure 17.1.Figure 17.5 Constant pressure system with unloader and variable setting pres...Figure 17.6 Typical layout of a constant pressure system supplied by a fixed...Figure 17.7 Pressure trends in the circuit, starting from an empty accumulat...Figure 17.8 Constant pressure circuit for braking applications.

18 Chapter 18Figure 18.1 Basic concepts for series (a, c) and for parallel (b, d) connect...Figure 18.2 Circuit with two actuators in series.Figure 18.3 Analysis of the motion of two actuators in parallel.Figure 18.4 Circuit with two actuators in parallel and directional control v...Figure 18.5 Use of a compensator for synchronizing the motion of two actuato...Figure 18.6 Volumetric coupling to achieve synchronism between actuators in ...Figure 18.7 Spool type flow divider: (a) simplified ISO symbol, detailed sch...Figure 18.8 Cross‐sectional view of a spool‐type flow divider.Figure 18.9 Application of a flow divider combiner (FDC) to control the exte...Figure 18.10 Spool type flow divider/combiner: detailed and simplified ISO s...Figure 18.11 Flow divider/combiner: operation as a flow divider.Figure 18.12 Flow divider/combiner: operation as a flow combiner.Figure 18.13 Cross‐sectional view of a spool type flow divider‐combinerFigure 18.14 Volumetric flow divider/combiner using intermediate dual rod cy...Figure 18.15 Two‐way rotary flow divider/combiner.Figure 18.16 Example of four‐way rotary flow divider/combiner. Each line is ...

19 Chapter 19Figure 19.1 Simplified circuit of a constant pressure system with multiple a...Figure 19.2 Flow rate reduction of a multi‐actuator constant pressure system...Figure 19.3 Energy plot for a constant pressure system with two actuators.Figure 19.4 Complete schematic of a constant pressure system.

20 Chapter 20Figure 20.1 Open center circuit with two actuators connected in parallel.Figure 20.2 Simplified schematic of the open center parallel connection.Figure 20.3 Energy plot representing a parallel open center system supplying...Figure 20.4 Advanced open center system with a variable displacement pump.Figure 20.5 Simplified schematic of a single actuator open center system (a)...Figure 20.6 Flow rates and pressure trends for two open center spools (large...Figure 20.7 Comparison of flow and pressure curves for two spools with simil...Figure 20.8 Open center circuit for the analysis of the simultaneous actuati...Figure 20.9 Load interference example with two different spool combinations....Figure 20.10 Tandem open center circuit. U1 has the priority over U2.Figure 20.11 Simplified circuit of an open center system with tandem connect...Figure 20.12 Open center circuit with series spool connection.Figure 20.13 Simplified open center architecture for excavators.

21 Chapter 21Figure 21.1 Principle of load sensing control of multiple actuator.Figure 21.2 Energy plot for the LS system of Figure 21.1 assuming p _U1 > p _U2 ...Figure 21.3 Multi‐actuator LS system with LS pump and LS valve.Figure 21.4 LS system with four actuators: the shuttle network comprises thr...Figure 21.5 Simplified representation of the LSPC pre‐compensated concept.Figure 21.6 Energy plot for the pre‐compensated LS system of Figure 21.5, as...Figure 21.7 Detailed representation of the Power loss term for the pre‐compe...Figure 21.8 Multi‐actuator pre‐compensated PCLS system.Figure 21.9 Cross‐section and equivalent schematic of a pre‐compensated dire...Figure 21.10 Detailed view of the compensator.Figure 21.11 Simplified representation of the LSPC post compensated concept....Figure 21.12 Energy plot for the post compensated LS system of Figure 21.11,...Figure 21.13 Detailed representation of the Power loss term for the post-com...Figure 21.14 Schematic of a two section post compensated valve.Figure 21.15 Section view of a post‐compensated proportional directional con...Figure 21.16 Basic circuit for the pre‐compensated LSPC.Figure 21.17 Simplified representation of the LSPC post compensated concept....Figure 21.18 Post‐compensated LS independent metering system.Figure 21.19 Regenerative feature with independent metering circuit.

22 Chapter 22Figure 22.1 Example of typical open center steering system for on‐highway ap...Figure 22.2 Detailed view of the power steering actuator.Figure 22.3 Cross‐section (X‐X) of the hydraulic servo system controlling th...Figure 22.4 Cross‐section of the spool and sleeve in neutral position.Figure 22.5 Operational diagram of a hydrostatic linear steering unit.Figure 22.6 Equivalent schematic of an open center rotary steering unit.Figure 22.7 Simplified cross‐section of a hydrostatic steering unit.Figure 22.8 Hydrostatic steering unit in the operating position.Figure 22.9 Different types of hydrostatic steering units.Figure 22.10 Reactive and nonreactive steering units.Figure 22.11 Priority circuit for fixed displacement pump flow supply.Figure 22.12 Operating modes of the priority valve.Figure 22.13 Cross‐section of constant flow priority valve.Figure 22.14 Priority valve for LS circuit.Figure 22.15 LS priority valve cartridge style architecture.

23 Chapter 23Figure 23.1 Conceptual schematic for hydrostatic transmissions and hydrostat...Figure 23.2 Four quadrant operation for an HT or HA: closed circuit configur...Figure 23.3 Different methods for implementing primary flow regulation: (a) ...Figure 23.4 Different methods for implementing reversal of flow direction in...Figure 23.5 Over‐center variable displacement pump/motor: relationship betwe...Figure 23.6 Classification and nomenclature of the different types of primar...

24 Chapter 24Figure 24.1 Parameters describing a generic hydrostatic transmission.Figure 24.2 HT with variable displacement primary unit and fixed displacemen...Figure 24.3 Transmission ratios (a), torque and power (b) for a PVMF transmi...Figure 24.4 Torque, power, and efficiency curves for a PVMF transmission wit...Figure 24.5 HT with fixed displacement primary unit and variable displacemen...Figure 24.6 Transmission ratios (a), torque and power (b) for a PFMV transmi...Figure 24.7 HT with variable displacement primary unit and variable displace...Figure 24.8 Control strategy for PVMV transmission.Figure 24.9 Transmission ratios (a), torque and power (b) for a PVMV transmi...Figure 24.10 Characteristic diagram for a PVMV transmission considering real...Figure 24.11 HT with variable displacement pump and dual displacement motor ...Figure 24.12 Ratios for a PVM2 hydrostatic transmission.Figure 24.13 Basic schematic of an open circuit hydrostatic transmission.Figure 24.14 Operating modes for the basic circuit in Figure 24.13.Figure 24.15 Typical schematic of an open circuit hydrostatic transmission: ...Figure 24.16 Displacement regulator for open circuit piston pumps with inter...Figure 24.17 Displacement regulator for open circuit pumps with electric fee...Figure 24.18 Typical circuit for a hydrostatic fan drive based on a pressure...Figure 24.19 Quadratic relationship between fan speed and torque. The pressu...Figure 24.20 Engine and fan power considerations for mechanical and hydrauli...Figure 24.21 Conceptual representation of a closed circuit HT.Figure 24.22 Detailed schematic of a closed circuit HT.Figure 24.23 Case drain flows lost in a closed circuit.Figure 24.24 Charge circuit in a closed circuit HT.Figure 24.25 Charge pump circuit inclusive of filtration (Z1).Figure 24.26 Cross‐port relief valves (RV2 and RV3) in a closed circuit HT....Figure 24.27 Solution with integrated cross‐port relief valves and charge pu...Figure 24.28 Closed circuit HT inclusive of the flushing circuit and filtrat...Figure 24.29 Flushing valve symbol.Figure 24.30 The flushing flow can be used to cool the motor housing.Figure 24.31 Displacement regulator for a closed circuit primary unit based ...Figure 24.32 Conceptual schematic of the automotive control.Figure 24.33 Displacement (a) and flow rate (b) of the main pump vs. engine ...Figure 24.34 Implementation of automotive control in a closed circuit pump....Figure 24.35 Example of electrohydraulic displacement regulator for motors....Figure 24.36 Example of automatic pressure regulator for motors.Figure 24.37 Displacement vs. pressure chart for an automatic pressure regul...

25 Chapter 25Figure 25.1 A transmission is the intermediate system between the engine and...Figure 25.2 Hypothetical direct connection between the combustion engine and...Figure 25.3 Four gears can be used to approximate the ideal traction curve....Figure 25.4 Combining an engine with a transmission with a variable ratio.Figure 25.5 Hydrostatic transmission used for propulsion.Figure 25.6 Technologies for variable ratio transmission systems.Figure 25.7 Schematic representation of an automatic transmission.Figure 25.8 Schematic representation of a torque converter and realistic tra...Figure 25.9 Generic schematics for power‐split transmissions. (a) Input‐coup...Figure 25.10 Planetary gear train (PGT): elements and symbolic representatio...Figure 25.11 Linear dependence between the angular velocities of the element...Figure 25.12 Power split obtained with a PGT.Figure 25.13 PGT operation as power summation or power splitting.Figure 25.14 Hydromechanical power‐split transmissions. (a) Output‐coupled. ...Figure 25.15 Detailed schematic for an output‐coupled hydromechanical power‐...Figure 25.16 Simplified schematic for an output‐coupled hydromechanical powe...Figure 25.17 Sequential control of the primary and secondary units for an ou...Figure 25.18 Behavior of the output‐coupled hydromechanical power‐split tran...Figure 25.19 Behavior of the output‐coupled hydromechanical power‐split tran...Figure 25.20 Behavior of the output‐coupled hydromechanical power‐split tran...Figure 25.21 Behavior of the output‐coupled hydromechanical power‐split tran...Figure 25.22 Summary of the operation modes for an output‐coupled hydromecha...Figure 25.23 Qualitative transmission efficiencies for an HT and for an outp...Figure 25.24 Simplifiedschematic for an input‐coupled hydromechanical power‐...Figure 25.25 Sequential control for the HT for an input‐coupled power‐split ...Figure 25.26 Behavior of the input‐coupled hydromechanical power‐split trans...Figure 25.27 Behavior of the input‐coupled hydromechanical power‐split trans...Figure 25.28 Behavior of the input‐coupled hydromechanical power‐split trans...Figure 25.29 Behavior of the input‐coupled hydromechanical power‐split trans...Figure 25.30 Summary of the operation modes for an input‐coupled hydromechan...Figure 25.31 Qualitative transmission efficiencies for both input‐coupled an...Figure 25.32 Series hybrid vehicle. 1 and 2 indicate energy converters.Figure 25.33 Series hydraulic hybrid (simplified schematic).Figure 25.34 Series hydraulic hybrid (realistic circuit).Figure 25.35 Parallel hybrid vehicle.Figure 25.36 Parallel hydraulic hybrid (simplified schematic).Figure 25.37 Parallel hydraulic hybrid (realistic schematic).Figure 25.38 Simplified schematic of the Ford hydraulic launch assist system...Figure 25.39 Series‐parallel hybrid vehicle.Figure 25.40 Hydraulic power‐split hybrid system (output coupled).Figure 25.41 Force balance on the vehicle for calculating the tractive effor...Figure 25.42 HT corner power and prime move power.

26 Chapter 26Figure 26.1 Open circuit hydrostatic actuator using counterbalance valves.Figure 26.2 HA circuit with single acting cylinder.Figure 26.3 Primary control of a differential cylinder in closed circuit.Figure 26.4 System behavior for the case of cylinder extension with resistiv...Figure 26.5 System behavior for the case of cylinder extension with low resi...Figure 26.6 System pressures for the case of cylinder extension.Figure 26.7 System behavior for the case of cylinder retraction with assisti...Figure 26.8 System behavior for the case of cylinder retraction with resisti...Figure 26.9 System pressures for the case of cylinder retraction.Figure 26.10 Summary of the operating conditions for the hydrostatic actuato...Figure 26.11 Closed circuit HA with accumulator and charge circuit sequence ...

27 Chapter 27Figure 27.1 Variables involved in the control of a hydraulic motor through s...Figure 27.2 Basic implementation of the secondary control principle inclusiv...Figure 27.3 One of the first concepts for controlling the displacement of a ...Figure 27.4 Regulation of the velocity of the secondary unit for the system ...Figure 27.5 Secondary control circuit with tachometric pump and additional f...Figure 27.6 Secondary control unit with full electronic feedback of speed, d...Figure 27.7 Secondary control circuit with multiple actuators.

28 1Figure A.1 A crane is a typical example of application where the combination...Figure A.2 Comparison of available torque (continuous line) and power (dotte...Figure A.3 Torque and power curves for a diesel engine. The chart shows how ...Figure A.4 Interaction between diesel engine and hydraulic pump.Figure A.5 Examples of machines powered by a diesel engine with different op...Figure A.6 Example of brake‐specific fuel consumption map for 150 kW to 700 ...Figure A.7 Operating principle and simplified implementation of a DC brushed...Figure A.8 Classification of DC brush motors based on type of excitation.Figure A.9 Torque vs. speed curves for different types of DC brushed motors....Figure A.10 DC power unit and equivalent schematic. A thermal switch (not re...Figure A.11 Performance curves of a DC power unit using a PM motor for diffe...Figure A.12 Example of duty cycle ratings for a DC power unit.Figure A.13 Two simple methods for controlling the speed of DC motors. The v...Figure A.14 The principle of operation of AC motors can be represented as a ...Figure A.15 Induction motor implementation with a single‐phase current.Figure A.16 Three‐phase and two‐pole induction motor: the rotating magnetic ...Figure A.17 Typical characteristic of an AC asynchronous induction motor.Figure A.18 Characteristic of an AC induction motor with variable frequency ...Figure A.19 Hydraulic power unit with induction motor and variable displacem...Figure A.20 Principle of operation of a synchronous motor with three pole pa...Figure A.21 Typical torque and power characteristics of a synchronous motor....Figure A.22 Torque limitation using two fixed displacement pumps.Figure A.23 Operating areas of a power limited supply using two fixed displa...Figure A.24 Common method for limiting the torque for an axial piston pump....Figure A.25 Detailed operation of the power limiting device.Figure A.26 Pressure–flow characteristic of a variable displacement pump wit...Figure A.27 Power limiting control integrated with load sensing and max pres...Figure A.28 Torque limiting control based on a cam‐adjusted relief valve.Figure A.29 Operating area for a cam‐operated torque limiting control.