' ~mannesm'a;;'~ • Rexroth Basic Principles and Components of Fluid Technology The Hydraulic Trainer Volume I Rexroth Hydraulics ~W@[J@llliJ~D©@ W@~lliJm® u[J@lDmJ®IT ~ Basic Principles and Components of Fluid Technology Instruction and Information on the Basic Principles and Components of Fluid Technology Authors H Exner· R Freitag· Dr.-Ing H Geis • R Lang J Oppolzer P Schwab· E Sumpf U.Ostendorff Hydromatik GmbH, Ulm M Reik HYDAC GmbH, Sulzbach Editor RudiA.Lang Mannesmann Rexroth GmbH Issued by Printed by lithography Photographs and Diagrams Issue MannesmannRexrolhAG 0-97813lohla MaIO JahnslraBe3·5·0·97816lohraMain Telefon +49/09352118-0 Telefax +49109352118·3972 Telex 689418n'd SChIeunungdflKl:: GmbH Utertstra8e27 0·97828 Marktheidenfeld am Main MaIOTeam Chemtegraphlsme GmbH Goldbachelstla6e 14 0-63739 Aschatlenburg 8rueninghaus Hydromatlk GmbH, Horb and Elchmgen HYDAC GmbH, Sulzbach Mannesmann Rexroth AG, lohr a Main RE 00 301/1978 RE 00 290110.91 {lSI issue, 1978} (2nd issue, 1991) IS8N 3·8023·0266-4 C 1991 by Mannesmann ReXlothAG All rights reserved-subjecl to revision Preface Hydraulics is a relatively new technology used in power transmission, which may be adapted to market requirements The use of hydraulic drives, as well as hydraulic open loop and closed loop control systems has gained in importance in the field of automation Nowadays, it is unusual to find an automatic production procedure which does not use hydraulic components However, in spite of the wide range of applications, there are still many more to be found Hence, manufacturers are expanding their experience by referring to literature and attending training courses This manual Basic Principles and Components of Hydraulics (from the series The Hydraulics Trainer) should aid you in gaining knowledge of hydraulics systems It is not only intended to be used as a training text, but also as an aid to the hydraulics system operator This trainer deals with the basic principles and functions of hydraulic components Relationships between functions are clarified by means of numerous tables, illustrations and diagrams This manual is therefore an invaluable reference aid for everyday work This manual is the result of collective work by a group of authors, to whom we are most grateful We would also like to thank Mr Rudi A Lang, who acted as project manager and editor In addition, Mr Herbert Wittholz must be thanked for his careful proofreading of the chapter on basic principles and also for his many useful comments Mannesmann Rexroth GmbH Lohr a Main Contents Preface Contents Chapter Basic Principles Rudi A Lang 1.1 1.2 1.2.1 1.2.2 1.3 2.1 2.1.1 2.1.2 2.1.3 2.2 2.2.1 2.2.2 2.2.3 2.3 2.3.1 2.3.2 2.4 2.4.1 2.4.2 2.4.2.1 2.4.2.2 2.4.2.3 2.4.3 2.4.3.1 2.4.3.2 2.4.3.3 2.4.3.4 3.1 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.3 Introduction Fluid technology Hydro-mechanics Hydrcrstatics Hydro-kinetics Types of energy ',ar15'e" (cho;"e) Parameters, symbols, units •, Physics terms Mass, force, pressure Mass Force Pressure energy, power Energy Power Velocity, acceleration Velocity Acceleration Hydro-mechanics Hydro·statics Pressure Pressure due to external forces Force transmission Pressure transmission Hydro-kinetics Flow law Law of conservation of energy Friction and pressure losses Types of flow Hydraulic systems Important characteristics of hydraulic systems Design 01 a hydraulic system Energy conversion Control of energy Transport of energy Further information Design of a simple hydraulic system 23 23 23 23 24 24 [...]... symbols to DIN ISO 12 19 3.3 .1 Step 1 (Figs 14 and 15 ) Hydraulic pump (1 ) is driven by a motor (electric motor or combustion engine) It sucks fluid from tank (2 ) and pushes it into the lines of the hydraulic circuit through various hydraulic devk:es up to the hydraulic cylinder (5 ) As long as there is no resistance to flow, the fluid is merely pushed further Cylinder (5 ) at the end of the line represents... 250 252 253 254 17 Chapter 14 Filters and Filtration Technology Martin Reik 1 2 2 .1 3 3 .1 4 4 .1 4.2 4.3 4.4 5 5 .1 5.2 6 7 8 8 .1 8.2 8.3 -8,4 8.5 8.6 8.7 9 9 .1 9.2 9.3 9.4 9.5 9.6 10 10 .1 10.2 10 .3 11 11 .1 11. 2 11 .3 Basics Notes on design and servicing Causes of contamination Analysis of solid particle contamination Classification systems for the degreee of contamination in a fluid Filtration... unit time is supplied to the cylinder, and the faster the k>ad will lift In the illustrations shown in Figs 14 to 19 , this principle (Fig 13 ) is extended to further devices, which _ control the direction of movement of the cylinder (directional valve), _ effect the speed of the cylinder (flow control valve), _ limit the load of the cylinder (pressure relief valve), _ prevent the system at rest from... directly back to the tank Fig 16 36 Basic Principles Fig 18 37 Basic Principles 3.3.3 Step 3 (Figs 18 and 19 ) In orderto change the speed of movement of the piston in the hydraulic cylinder (5 ), the amount of flow to the cylinder must be controlled This may be achieved, using a flow control yalve (7 ) The cross-sectional area of a pipe may be changed, using a flow control valve If the area is decreased,... cylinder (5 ) The piston in cylinder (5 ) hence moves slower The excess liquid, which is now delivered by pump (1 ) , is drained to tank (2 ) via pressure relief valve (4 ) The following pressures occur in a hydraulic circuit: - pressure set at pressure relief valve (4 ) acts between hydraulic pump (1 ) and flow control valve (7 ) - pressure dependent on load acts between flow and control valve (7 ) and cylinder (5 ). .. Pressure therefore increases until it is in a position to overcome this resistance, Le until the piston in the cylinder (5 ) moves The direction of movement of the piston in the cylinder (5 ) is controlled via directional FIQ 13 : Principle of a hydraulic circuit The piston of a hand pump is loaded with a force (Fig 13 ) This force divided by the piston area results in the att~.ab'e pressure (p valve (6 ) At... example (Fig 3) will demonstrate how the hydro-static pressure may be used s1 A2 S2 A1 The work done by the force piston (1 ) W1 is equal to the work done by the load piston (2 ) W2 W1 F1 ·s1 , W2 = F2 • 52' Fig 3:' Example of force transmission 29 Basic Principles 2.4.2.3 Pressure transmission 2.4.3 .1 Flow Law If liquid flows through a pipe of varying diameters, at any particular time the same volume. .. means, that the velocity of liquid flow must increase at a narrow point (Fig 5) Flow 0 is given by the volume of fluid V divided by timet o VII Fig 4: Pressure transmission Two pistons of different sizes (Fig 4: 1 and 2) are fixed together by means of a rod If area A 1 is pressurised with pressure Pl' a force F 1 is produced at piston (1 ) Force F1 is transferred via the rod 10 area ~ of piston (2 ) and hence... movements Table 1: Features of types of energy transfer see footnote on page 23 2) as part of fluid power, even though hydraulics deals with far more than just fluid power 1) 24 as part of fluid power, even though pneunatics deals with far more than just fluid power 3) Basic Principles 1. 4 Quantities, symbols, units (see DIN 13 01 part 1 and DIN 13 04 part 1) Quantity Symbol f Length Distance 51 unit Dimension... valve), _ prevent the system at rest from being completely drained via the hydraulic pump (check valve) and _ supply the hydraulic circuit continuously with press,ure liquid (via an electric motor driven hydraulic pump) 34 Fig 14 Basic Principles Fig 15 35 Basic Principles Fig 17 36 Basic Principles 3.3.2 Step 2 (Figs 16 and 17 ) So that the hydraulic circuit is protected from excess pressures and hence from ... regulations 15 1 15 2 15 2 15 6 15 6 15 8 15 9 15 9 16 2 16 4 16 5 16 5 16 6 16 6 16 7 16 7 16 9 17 0 17 1 17 1 17 2 17 3 17 3 17 5 17 5 17 5 13 Chapter 10 Non Return Valves Dr Harald Geis, Johann Oppolzer 3 .1 3.2 3.3... Summary of common adjustment methods in axial piston units 96 10 2 10 6 10 8 10 9 11 0 11 3 11 3 11 4 11 4 11 5 11 6 11 6 11 7 Chapter Hydraulic Cylinders Paul Schwab 2 .1 2.2 2.3 3 .1 3.2 5 .1 5.2 6 .1 6.2 7 .1 7.2... Servocylinder Servo manifold 12 3 12 3 12 3 12 4 12 5 12 7 12 7 13 0 13 5 13 9 13 9 14 0 14 0 14 0 14 0 14 1 14 1 14 4 11 Chapter Rotary actuators Paul Schwab 2 .1 2.2 2.3 2.4 2.5 GeneraL ~ 1~ Rotary piston/rotary